This guide is a collection of techniques for improving the security and privacy of macOS on Apple silicon Macs. It targets experienced users who want security practices commonly used by organizations, but is also suitable for novice users with an interest in privacy and security.
For securing computers in an organization, refer to the security guidelines from NIST, a U.S. government cybersecurity standards organization
This guide is provided "as is" - without warranties of any kind. You are solely responsible for any consequences of following it.
To suggest a change, submit a pull request or open an issue.
- Basics
- Threat modeling
- Hardware
- Installing macOS
- First boot
- Admin and user accounts
- Firmware
- FileVault
- Lockdown Mode
- Firewall
- Services
- Siri Suggestions and Spotlight
- Homebrew
- DNS
- Certificate authorities
- Privoxy
- Browser
- Tor
- VPN
- PGP/GPG
- Messengers
- Viruses and malware
- System Integrity Protection
- Metadata and artifacts
- Authentication
- Backup
- Wi-Fi
- SSH
- Physical access
- Monitoring
- Miscellaneous
- Related software
- Additional resources
Apply general security best practices:
-
Create a threat model
- What needs protection and from whom? Is the adversary a three-letter agency, an eavesdropper on a network, or a determined Advanced Persistent Threat (APT) orchestrating a campaign against you?
- Recognize threats and learn how to reduce the number of ways an attacker could potentially access a system or data.
-
Keep the system and software up to date
- Regularly install available updates for the operating system and all applications.
- Updates are installed in System Settings or with the
softwareupdatecommand-line utility. Neither requires an Apple Account. - Subscribe to the Apple security-announce mailing list or check Apple security releases.
-
Encrypt sensitive data
- In addition to FileVault storage encryption, use the built-in password manager to protect passwords and other sensitive data.
-
Ensure data availability
- Create regular backups of critical data and be ready to restore from a backup in case of compromise.
- Encrypt locally before copying backups to unencrypted external media or the "cloud"; alternatively, enable end-to-end encryption.
- Verify backups by accessing them on a scheduled basis.
-
Click carefully
- Ultimately, the security of a system depends on the capabilities and habits of its administrator.
- Take care when installing new software: install it only from sources the developer identifies as official, such as their website or GitHub repository.
The most important step to meaningfully improve security and privacy is to create a threat model. This creates an understanding of potential adversaries and their motivations, which leads to stronger defenses. Each individual should develop their own unique threat model. Threat models are likely to change over time and should be periodically re-assessed.
Assets may include a phone, laptop, credentials, and personal information, such as browsing history.
List them in order of importance, starting with those most worth protecting.
Define whom you are defending against. Start by defining the motivation each adversary might have to attack important assets. Financial gain is a big motivator for many attackers, for example.
To counter adversaries, understand both their capabilities and limitations. Rank them from least to most capable. For example, a common thief operates opportunistically: they will likely be defeated by the basics, such as screen lock and encrypted storage with strong passwords. A more sophisticated and determined adversary may require fully powering off a device when not in use to clear credentials from memory and stronger authentication mechanisms.
Choose the best mitigation for each threat. For example, avoid writing passwords on paper if a roommate might find them, or encrypt storage to protect its data if it is stolen.
Security should be balanced with usability: every mitigation should counter some adversarial capability to justify any inconvenience. If you can't think of any more capabilities your adversaries might have and you've implemented mitigations for them all, your work is done.
The following is an example of assets to protect:
| Adversary | Motivation | Capabilities | Mitigation |
|---|---|---|---|
| Roommate | See private chats or browsing history | Close proximity; can see screen or observe credentials | Use biometric (fingerprint or face) authentication, use privacy screen, keep phone locked when not using it |
| Thief | Unlock phone and steal personal info and drain bank accounts, sell phone for money | Observe password being entered, steal logged-in device left unattended | Maintain physical custody of device at all times, lock devices when not in use, avoid typing password in public view, use Find My or similar services to track or remotely disable stolen devices |
| Criminal | Financial gain | Social engineering (tricking a user into revealing information or taking unsafe actions), readily-available malware, password reuse, exploiting vulnerabilities | Sandbox software, enable OS security features, maintain software updates automatically |
| Corporation | Marketing based on user data | Telemetry and behavioral data collection | Block network connections, reset device-specific identifiers, avoid adding payment data |
| Nation State/APT | Targeted surveillance | Passive surveillance of internet infrastructure, advanced encryption analysis | Use open-source software, strong diceware credentials, hardware with secure element, shut down devices when not in use, tripwire/honeypot/canary tokens alerts |
Read more about threat modeling.
Important
Macs with Intel CPUs have security vulnerabilities on a hardware level which cannot be patched.
macOS is most secure running on Apple hardware with Apple silicon; in general, newer models offer stronger security guarantees. Avoid non-Apple hardware running macOS and systems which do not support the latest macOS release, as Apple does not patch all vulnerabilities in legacy versions.
When using a wireless keyboard, mouse, headphones, or other accessory, Apple accessories are generally the most secure option because macOS updates them automatically. They support the latest Bluetooth features such as BLE Privacy which randomizes the hardware address to reduce tracking, which is not always available with third-party accessories.
When purchasing a Mac, consider paying in cash rather than ordering online or purchasing with a credit/debit card, to limit identifying information linked to the purchase.
There are several ways to install macOS.
Install the latest supported version of macOS; newer versions of macOS include security fixes and other improvements not available in previous releases.
As part of Apple's theft prevention system, Apple silicon Macs connect to Apple servers when macOS is installed to check against the database of lost or stolen systems.
Read about how this process works.
An Apple Account is not required to use macOS, but necessary to access the App Store and most Apple services, including iCloud and Apple Music.
You can disable the syncing later or enable end-to-end encryption for data stored in iCloud. You can control the data associated with Apple Account or completely delete it.
The App Store is a software distribution platform where applications are reviewed by Apple.
App Store applications are required to use App Sandbox and Hardened Runtime (security features restricting what apps can do, making some attacks more difficult). It also offers automatic software updates.
Using the App Store requires an Apple Account, which can pose a privacy risk.
On Apple silicon, macOS includes Apple's Virtualization framework, which supports macOS and Windows 11 ARM virtual machines through tools such as:
- UTM - Follow the documentation to create macOS and other VMs.
- VirtualBuddy - GUI for virtualizing macOS 12+ on Apple silicon.
- Bushel - A lightweight, free VM app. On first launch, select "Ask App Not to Track".
- VMware Fusion - Now free under Broadcom. Clean UI, easy macOS setup, and supports Windows 11 ARM.
- tart (CLI) - Command‑line VM control; install with Homebrew.
- Parallels - Paid option with strong integration.
Warning
VMware requires a Broadcom account and acceptance of agreements before download. Parallels requires an account, payment details, and other data - see the privacy notice.
Apple Container provides a native command-line workflow for running Linux container images on macOS. Unlike container runtimes that share a single Linux virtual machine, Apple Container runs each container in an isolated, lightweight virtual machine using macOS virtualization capabilities. This provides a stronger isolation boundary between workloads and the host operating system.
When macOS starts for the first time, Setup Assistant requires the creation of a primary account.
Set a strong password without a hint.
Avoid personally identifiable names: the computer name (such as "John Appleseed's MacBook") is broadcast over local networks and visible to other devices.
The system name can be configured in System Settings > About or with the following commands:
sudo scutil --set ComputerName MacBook
sudo scutil --set LocalHostName MacBookThe first user account created is always an administrator account. Administrator accounts belong to the admin group and can use sudo (a command that grants temporary administrator access) to run commands with elevated privileges, up to and including root (full system) control. Any program the administrator executes can potentially obtain the same access, and sudo may have vulnerabilities exploited by concurrently-running software.
It is considered a best practice to use a dedicated standard account for regular, every-day work and only use the administrator account for software and system installation, configuration and updates.
It is not required to ever log in with the admin account via the macOS login screen. When a Terminal command requires administrator privileges, the system will prompt for authentication and Terminal continues using those privileges. To that end, Apple provides recommendations for hiding the admin account and its home directory.
- Only administrators can install applications in
/Applications(local directory). Finder and Installer will prompt a standard user with a password prompt asking an administrator to approve the change. Many applications can be installed in~/Applicationsinstead. As a rule of thumb, applications which do not require admin access – or do not complain about not being installed in/Applications– should be installed in the user directory, the rest in the local directory. App Store applications are still installed in/Applicationsand require no additional authentication. sudois not available in shells of the standard user, which requires usingsuorloginto enter a shell of the admin account. This can make some maneuvers trickier and requires some basic experience with command-line interfaces.- System Settings and several system utilities (e.g., Wi-Fi Diagnostics) require administrator permission for full functionality. Some System Settings need to be unlocked by selecting the lock icon. Some applications will simply prompt for authentication upon opening, others must be opened by an admin account directly to access all functions (e.g., Console).
- There are third-party applications that will not work correctly because they assume the user account is an admin. These programs may have to be executed by the admin account, or by using the
openutility. - See additional discussion in issue 167.
Accounts can be created and managed in System Settings. On existing systems, it is generally easier to create a second admin account and then change the original account from an administrator account to a standard account. Newly-installed systems should instead add a standard account after setup.
Demoting an account can be done either from the new admin account in System Settings – the other account must be logged out – or by executing these commands (it may not be necessary to execute both, see issue 179):
sudo dscl . -delete /Groups/admin GroupMembership <username>
sudo dscl . -delete /Groups/admin GroupMembers <GeneratedUID>To obtain an account's GeneratedUID:
dscl . -read /Users/<username> GeneratedUIDSee also this post for more information about how macOS determines group membership.
Verify that firmware security is set to Full Security to prevent tampering with the system. This is the default setting.
All Apple silicon Macs encrypt storage by default. Enabling FileVault requires a password before macOS can access the encrypted volume. The EFF has a guide on generating strong and memorable passwords.
The FileVault password also protects the firmware, which prevents booting from anything other than the designated startup disk, accessing Recovery, and reviving it with device firmware update (DFU) mode.
FileVault will prompt to set a recovery key, which should be stored in a safe location if used. FileVault also offers an option to use iCloud for recovery.
Lockdown Mode significantly reduces attack surface by disabling system and application features commonly exploited in targeted attacks.
When Lockdown Mode is enabled, Safari has an option to exclude trusted websites from restrictions.
There are several types of firewalls available for macOS.
The built-in firewall provides basic protection and blocks incoming connections only. It can neither monitor nor block outgoing connections.
It can be controlled by the Firewall tab of Network in System Settings, or with the following commands.
Enable the firewall and Stealth Mode:
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setglobalstate on
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setstealthmode onAttackers scan networks to identify systems to target. When Stealth Mode is enabled, responses are not sent to connection attempts from closed ports, making the system more difficult to detect.
Prevent built-in and downloaded software from automatically receiving incoming connections:
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setallowsigned off
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setallowsignedapp offApplications signed by a valid certificate authority are automatically added to the list of allowed apps, rather than prompting the user to authorize them. Apps included in macOS are signed by Apple and are allowed to receive incoming connections when this setting is enabled.
If an unsigned app not listed in the firewall list is opened, a dialog appears with options to Allow or Deny connections. If allowed, macOS signs the application and adds it to the firewall list. If denied, macOS adds it to the list and denies incoming connections.
After interacting with socketfilterfw, restart the process by sending a SIGHUP signal:
sudo pkill -HUP socketfilterfwEnabling the application layer firewall and disabling incoming connections for built-in software prevents AirDrop from functioning correctly. For AirDrop to work, both sharingd and rapportd require exceptions in the firewall:
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --add /usr/libexec/sharingd
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --unblockapp /usr/libexec/sharingd
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --add /usr/libexec/rapportd
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --unblockapp /usr/libexec/rapportdApplications such as Little Snitch, Radio Silence, and LuLu provide a balance between usability and security.
These programs are capable of monitoring and blocking both incoming and outgoing connections. However, they may require a closed-source system extension.
If frequent allow-or-block prompts are overwhelming, begin with Silent Mode configured to allow connections. Review the configuration periodically to understand each application's network activity.
Note
A root-level compromise can undermine host-based network controls, depending on the product and system configuration.
macOS also includes a powerful, highly customizable kernel-level firewall called pf. However, it is the most complex option and is managed with pfctl and configuration files.
pf can also be controlled with a GUI application such as Murus.
Many books and articles cover the pf firewall. The following example shows how to block traffic by IP address.
Add the following rules to a file named pf.rules:
wifi = "en0"
ether = "en7"
set block-policy drop
set fingerprints "/etc/pf.os"
set ruleset-optimization basic
set skip on lo0
scrub in all no-df
table <blocklist> persist
block in log
block in log quick from no-route to any
block log on $wifi from { <blocklist> } to any
block log on $wifi from any to { <blocklist> }
antispoof quick for { $wifi $ether }
pass out proto tcp from { $wifi $ether } to any keep state
pass out proto udp from { $wifi $ether } to any keep state
pass out proto icmp from $wifi to any keep state
Use the following commands to control the firewall:
| function | command |
|---|---|
| enable firewall with config | sudo pfctl -e -f pf.rules |
| disable firewall | sudo pfctl -d |
| add address to blocklist | sudo pfctl -t blocklist -T add 1.2.3.4 |
| view the blocklist | sudo pfctl -t blocklist -T show |
| create log interface | sudo ifconfig pflog0 create |
| monitor blocked packets | sudo tcpdump -ni pflog0 |
pf can block access to ranges of network addresses, for example to an entire organization:
Query Merit RADb for the list of networks in use by an autonomous system (a large network operated by a single organization), such as Facebook:
whois -h whois.radb.net '!gAS32934'Copy and paste the list of networks returned into the blocklist command:
sudo pfctl -t blocklist -T add 31.13.24.0/21 31.13.64.0/24 157.240.0.0/16Confirm the addresses were added:
$ sudo pfctl -t blocklist -T show
No ALTQ support in kernel
ALTQ related functions disabled
31.13.24.0/21
31.13.64.0/24
157.240.0.0/16Confirm network traffic is blocked to those addresses (DNS requests will still work):
$ dig a +short facebook.com
157.240.2.35
$ curl --connect-timeout 5 -I http://facebook.com/
* Trying 157.240.2.35...
* TCP_NODELAY set
* Connection timed out after 5002 milliseconds
* Closing connection 0
curl: (28) Connection timed out after 5002 milliseconds
$ sudo tcpdump -tqni pflog0 'host 157.240.2.35'
IP 192.168.1.1.62771 > 157.240.2.35.80: tcp 0
IP 192.168.1.1.62771 > 157.240.2.35.80: tcp 0
IP 192.168.1.1.62771 > 157.240.2.35.80: tcp 0
IP 192.168.1.1.62771 > 157.240.2.35.80: tcp 0
IP 192.168.1.1.62771 > 157.240.2.35.80: tcp 0Outgoing TCP SYN packets are blocked, so a TCP connection is not established, blocking traffic to the destination host at the IP layer.
See drduh/config/scripts/pf-blocklist.sh for more inspiration.
Services on macOS are managed by launchd.
Administrator accounts can modify services and extensions in System Settings.
| function | command |
|---|---|
| view loaded user jobs | launchctl list |
| view loaded system jobs | sudo launchctl list |
| examine a service | launchctl list com.apple.Finder |
| list installed system daemons | ls /System/Library/LaunchDaemons |
| list installed system agents | ls /System/Library/LaunchAgents |
| read a service configuration | defaults read /System/Library/LaunchAgents/com.apple.Finder |
| list system extensions | systemextensionsctl list |
Important
System services are protected by SIP. Do not disable SIP just to modify system services as it is a fundamental part of the macOS security model. Disabling system services may also cause system instability.
To view the status of services:
find /var/db/com.apple.xpc.launchd/ -type f -print -exec defaults read {} \; 2>/dev/nullSee script management with launchd and launchd.info for more information.
Apple is moving many Siri functions to on-device processing, but using Siri Suggestions or Spotlight may still send some information to Apple. See Apple's Privacy Policy to see exactly what is sent and how to disable it.
If a program is not available through the App Store, consider using Homebrew.
Warning
Homebrew requests "App Management" (or "Full Disk Access") permission to Terminal. This is risky: any non-sandboxed application can execute code with Terminal's TCC permissions by adding a malicious command to the shell configuration. Treat granting App Management or Full Disk Access permissions as equivalent to disabling TCC protections for processes that can control or execute commands through Terminal.
Remember to periodically run brew upgrade on trusted and secure networks to download and install software updates. To get information on a package before installation, run brew info <package> and check its formula online. You may also wish to enable additional security options, such as HOMEBREW_NO_INSECURE_REDIRECT=1
According to Homebrew's Anonymous Analytics, Homebrew collects anonymous usage analytics and reports them to a self-hosted InfluxDB instance.
To opt out of Homebrew analytics, run brew analytics off or set HOMEBREW_NO_ANALYTICS=1 in the shell startup file.
macOS features "DNS configuration profiles" for configuring encrypted DNS, filtering, and DNSSEC.
DNS profiles can be created or obtained from providers such as Quad9, AdGuard and NextDNS.
Use the hosts file to block domains associated with malware, advertising, and other unwanted services.
To block a domain by A record, append any one of the following lines to /etc/hosts:
0 example.com
0.0.0.0 example.com
127.0.0.1 example.com
Note
IPv6 uses AAAA records rather than A records: block IPv6 connections by including ::1 example.com entries.
Many domain lists are available online. Before appending one to /etc/hosts, ensure each entry begins with 0, 0.0.0.0, or 127.0.0.1, and retain the 127.0.0.1 localhost entry.
Popular hosts lists include:
To downloaded and add a list to the end of the hosts file, use the tee command:
curl https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts | sudo tee -a /etc/hostsLittle Snitch also supports blocklists.
To encrypt DNS traffic, consider DNSCrypt/dnscrypt-proxy. When combined with Dnsmasq and DNSSEC, it can improve the privacy and integrity of DNS resolution.
Install DNSCrypt from Homebrew and follow the instructions to configure and start dnscrypt-proxy:
brew install dnscrypt-proxyWhen using DNSCrypt with Dnsmasq, locate the DNSCrypt configuration file by running:
brew info dnscrypt-proxyThis command should display a path such as /usr/local/etc/dnscrypt-proxy.toml.
By default, dnscrypt-proxy listens on localhost (127.0.0.1) on port 53 and balances requests across a set of resolvers. Modify the configuration and change listen_addresses to use a port other than 53, such as 5355:
listen_addresses = ['127.0.0.1:5355', '[::1]:5355']
Start DNSCrypt:
sudo brew services restart dnscrypt-proxyConfirm DNSCrypt is running:
$ sudo lsof +c 15 -Pni UDP:5355
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
dnscrypt-proxy 15244 nobody 7u IPv4 0x1337f85ff9f8beef 0t0 UDP 127.0.0.1:5355
dnscrypt-proxy 15244 nobody 10u IPv6 0x1337f85ff9f8beef 0t0 UDP [::1]:5355
dnscrypt-proxy 15244 nobody 12u IPv4 0x1337f85ff9f8beef 0t0 UDP 127.0.0.1:5355
dnscrypt-proxy 15244 nobody 14u IPv6 0x1337f85ff9f8beef 0t0 UDP [::1]:5355Applications may use their own DNS servers. If you use dnscrypt-proxy, you can block other DNS traffic with the following pf rules:
block drop quick on !lo0 proto udp from any to any port = 53
block drop quick on !lo0 proto tcp from any to any port = 53Note
DNS requests can bypass the privacy service and reveal name lookups, if not properly configured.
dnsmasq can cache replies, prevent upstream queries for unqualified names, and block entire top-level domains.
Use it in combination with DNSCrypt to encrypt DNS traffic.
If you do not use DNSCrypt, at minimum choose a DNS resolver other than the one provided by the ISP. Two popular alternatives are Google DNS and OpenDNS.
Install Dnsmasq:
brew install dnsmasqDownload and edit drduh/config/dnsmasq.conf or the default configuration file.
See drduh/config/domains for example domain lists that can be added to block specific destinations.
Install and start the program (sudo is required to bind to privileged port 53):
sudo brew services start dnsmasqTo set dnsmasq as the local DNS server, open System Settings > Network and select the network connection currently in use (such as Wi-Fi), then open the DNS tab, select +, and add 127.0.0.1, or use:
sudo networksetup -setdnsservers "Wi-Fi" 127.0.0.1Confirm Dnsmasq is configured:
$ scutil --dns | head
DNS configuration
resolver #1
search domain[0] : whatever
nameserver[0] : 127.0.0.1
flags : Request A records, Request AAAA records
reach : 0x00030002 (Reachable,Local Address,Directly Reachable Address)
$ networksetup -getdnsservers "Wi-Fi"
127.0.0.1Note
Some VPN applications override DNS settings on connect. See issue 24 and drduh/config/scripts/macos-dns.sh.
macOS is configured with over 150 root authority certificates issued by corporations and government agencies from around the world. These Certificate Authorities (CAs) are capable of issuing TLS and code-signing certificates. Apple blocks certificates when a CA proves to be untrustworthy and requires certain criteria for inclusion.
For more information, see CA/Browser Forum.
Inspect root certificates in Keychain Access, under the System Roots tab or by using the security command line tool and /System/Library/Keychains/SystemRootCertificates.keychain file.
To disable a certificate authority, mark it as Never Trust and close the window to confirm.
Doing so may reduce the risk of MITM attacks, in which a coerced or compromised certificate authority could issue a fraudulent certificate, allowing encrypted traffic to be silently intercepted.
Consider using Privoxy as a local proxy to filter web traffic.
Install and start Privoxy using Homebrew:
brew install privoxy
brew services start privoxyAlternatively, a signed installation package for Privoxy is available from their website or Sourceforge. The signed package is more secure than the Homebrew version and receives support from the Privoxy project.
By default, Privoxy listens on local TCP port 8118.
Set the system HTTP proxy for the active network interface to 127.0.0.1 and port 8118:
sudo networksetup -setwebproxy "Wi-Fi" 127.0.0.1 8118Set the system HTTPS proxy:
sudo networksetup -setsecurewebproxy "Wi-Fi" 127.0.0.1 8118The proxy can also be set in System Settings > Network > Details > Proxies.
Confirm the proxy is set:
$ scutil --proxy
<dictionary> {
ExceptionsList : <array> {
0 : *.local
1 : 169.254/16
}
FTPPassive : 1
HTTPEnable : 1
HTTPPort : 8118
HTTPProxy : 127.0.0.1
}Although the majority of Web traffic is encrypted, Privoxy can filter by matching website names. For example, the following rules block all traffic, except to .net and github.com and all apple domains:
{ +block{all} }
.
{ -block }
.apple.
.github.com
.netTo block Facebook domains:
{ +block{facebook} }
.cdninstagram.
.facebook*.
.fb.
.fbcdn*.
.fbinfra.
.fbsbx.
.fbstatic*.
.fbsv.
.fburl.
.instagr.am
.tfbnw.
.thefacebook.
fb*.akamaihd.netSee drduh/config/privoxy/config and drduh/config/privoxy/user.action for additional Privoxy examples. Privoxy does not need to be restarted after editing filter rules.
To verify traffic is blocked or redirected, use curl or open the Privoxy interface at http://p.p in a browser:
$ ALL_PROXY=127.0.0.1:8118 curl example.com -IL | head
HTTP/1.1 403 Request blocked by Privoxy
Content-Length: 9001
Content-Type: text/html
Cache-Control: no-cache
Pragma: no-cache
$ ALL_PROXY=127.0.0.1:8118 curl github.com -IL | head
HTTP/1.1 302 Local Redirect from Privoxy
Location: https://github.com/
Content-Length: 0
HTTP/1.1 200 Connection established
HTTP/2 200
content-type: text/html; charset=utf-8Note
Applications and services can ignore proxy setting; redirect traffic through a proxy without configuring each app separately using pf.
The Web browser creates numerous security and privacy risks, as its fundamental job is to download and execute untrusted code from the Internet.
An important security property of browsers is the Same Origin Policy (SOP), which prevents one website from reading data from another website. If the SOP is compromised, the security of the entire browser is at risk.
Some browser exploits rely on social engineering to gain persistence (ability to remain active after the initial attack). Be mindful when visiting untrusted sites and especially careful when downloading unrecognized software.
Browser extensions pose a significant security risk: a malicious or poorly-made extension can compromise everything in the browser, including credentials. This affects Firefox and Chrome alike. The use of browser extensions should be limited to critically necessary ones, published by trustworthy developers only.
Mozilla Firefox, Google Chrome, Safari, and Tor Browser are popular browsers, each with unique features and individual purposes.
Firefox replaced major parts of its infrastructure and codebase under the projects Quantum and Photon. Part of the Quantum project is to replace C++ code with Rust. Rust is a systems programming language with a focus on security and thread safety. It is expected that Rust adoption will greatly improve the overall security posture of Firefox.
Firefox offers a comparable security model to Chrome, including a bug bounty program for responsible disclosure of vulnerabilities. Firefox follows a four-week release cycle.
See drduh/config/firefox.user.js and arkenfox/user.js for recommended configurations for Firefox. Also see NoScript, an extension which allows selective script blocking.
Firefox focuses on user privacy. It supports tracking protection in Private Browsing mode. The tracking protection can be enabled for the default account, although it may break the browsing experience on some websites. Firefox in Strict tracking protection mode will randomize fingerprints to defend against tracking. Firefox offers separate user profiles. Browsing can also be delineated with Multi-Account Containers.
Firefox only supports Web Extensions through the WebExtension API, which is very similar to Chrome. Submission of Web Extensions in Firefox is free. Web Extensions in Firefox most of the time are open-source, although certain Web Extensions are proprietary.
Google Chrome is based on the open-source Chromium project with certain proprietary components, such as:
- Chrome Web Store
- Automatic updates with GoogleSoftwareUpdateDaemon
- Usage tracking and crash reporting, which can be disabled through Chrome's settings
- Media Codec support for proprietary codecs
- PDF viewer
- Non-optional tracking. Google Chrome installer includes a randomly generated token, which is sent to Google. The RLZ identifier stores information in the form of encoded strings, such as the source of the download and install time. It does not include personal information and it's used to measure the effectiveness of a promotional campaign. Chrome downloaded from Google's website doesn't have the RLZ identifier. The source code to decode the strings is made open by Google.
Chrome offers account sync between multiple devices, including credentials; the data is encrypted with the account password.
The Chrome Web Store requires a 5 USD registration fee to submit extensions. This allows development of open-source Web Extensions which do not aim to monetize through usage.
Chrome has the largest share of global usage and is the preferred target platform for the majority of developers. Major technologies are based on Chrome's open-source components, such as node.js which uses Chrome's V8 Engine and the Electron framework, which is based on Chromium and node.js. Chrome's vast user base makes it the most attractive target for threat actors and security researchers. Despite constant attacks, Chrome has retained an impressive security track record over the years. This is not a small feat.
Chrome offers separate profiles, robust sandboxing, frequent updates, and carries impressive credentials. In addition, Google offers a very lucrative bounty program for reporting vulnerabilities, along with its own Project Zero team. This means that a large number of highly talented and motivated people are constantly auditing and securing Chrome code.
Create separate browser profiles to reduce cross-site scripting risk and compartmentalize identities. In each profile, disable JavaScript in settings and configure allowed origins. Also consider disabling V8 optimization (JavaScript-engine performance features) in Settings - see this explanation for the security trade-offs.
Block trackers with uBlock Origin Lite.
Disable DNS prefetching (see DNS Prefetching and Its Privacy Implications (pdf)). Chrome may attempt to resolve DNS using Google's 8.8.8.8 and 8.8.4.4 public nameservers.
See Chromium Security and Chromium Privacy for more information. Read Google's privacy policy to understand how personal information is collected and used.
Safari is the default browser on macOS. It is also the most optimized browser for reducing battery use. Safari has both open-source and proprietary components. Safari is based on the open-source Web Engine WebKit, which is ubiquitous among the macOS ecosystem. WebKit is used by Apple apps such as Mail, Books, and the App Store. Chrome's Blink engine is a fork of WebKit and both engines share a number of similarities.
Safari supports certain unique features that benefit user security and privacy. Content blockers enable the creation of content blocking rules without using JavaScript. This rule based approach greatly improves memory use, security, and privacy. Safari 11 introduced Intelligent Tracking Prevention, which removes tracking data stored in Safari after a period of non-interaction by the user from the tracker's website. Safari can randomize the browser fingerprint to reduce tracking. Safari does not support certain features such as WebUSB or the Battery API intentionally for security and privacy reasons. Private tabs in Safari have isolated cookies and cache that is destroyed when you close the tab. Safari also support Profiles which are equivalent to Firefox's Multi-Account Containers for separating cookies and browsing. Safari can be made significantly more secure with lockdown mode, which can be disabled per-site. Read more about tracking prevention in Safari.
Safari offers an invite-only bounty program for bug reporting to a select number of security researchers. The bounty program was announced during Apple's presentation at BlackHat 2016.
Web Extensions in Safari have an additional option to use native code in Safari's sandbox environment, in addition to Web Extension APIs. Web Extensions in Safari are also distributed through Apple App Store. App Store submission comes with the added benefit of Web Extension code being audited by Apple. On the other hand App Store submission comes at a steep cost. Yearly developer subscription fee costs 100 USD (in contrast to Chrome's 5 USD fee and Firefox's free submission). The high cost is prohibitive for the majority of open-source developers. As a result, Safari has very few extensions to choose from. However, keep the high cost in mind when installing extensions. It is expected that most Web Extensions will have some way of monetizing usage to cover development costs. Avoid Web Extensions without open-source code available for review.
Safari syncs user preferences and passwords with iCloud Keychain. In order to be viewed in plain text, a user must input the account password of the current device. This means that users can sync data across devices with added security.
Safari implements new web features more slowly than Chrome or Firefox, but security patches are delivered promptly through system updates.
See also el1t/uBlock-Safari to disable hyperlink auditing beacons.
Web browsers reveal information in several ways, for example through the Navigator interface, which may include information such as the browser version, operating system, site permissions, and the device battery level. Many websites also use canvas fingerprinting to uniquely identify users across sessions.
For more information about security-conscious browsing and what data is sent by the browser, see HowTo: Privacy & Security Conscious Browsing, browserleaks.com, Am I Unique? and EFF Cover Your Tracks resources.
To hinder third-party trackers, it is recommended to disable third-party cookies altogether. Safari, Firefox, and Chrome all block third-party cookies by default. A third-party cookie is a cookie associated with a file requested by a different domain than the one the user is currently viewing. Most of the time third-party cookies are used to create browsing profiles by tracking a user's movement on the web. Disabling third-party cookies prevents HTTP responses and scripts from other domains from setting cookies. Moreover, cookies are removed from requests to domains that are not the document origin domain, so cookies are only sent to the current site that is being viewed.
Also be aware of WebRTC, which may reveal local or public (if connected to a VPN) IP address(es). In Firefox and Chrome/Chromium, this feature can be disabled with uBlock Origin. Lockdown mode also disables WebRTC in Safari.
Tor is an anonymizing network which can be used for browsing the Web with additional privacy. Tor Browser is a modified version of Firefox with a proxy to access the Tor network.
Download Tor Browser from Tor Project, both dmg and asc files for verification:
$ cd ~/Downloads
$ file tor-browser-macos-*
tor-browser-macos-15.0.17.dmg: XZ compressed data, checksum NONE
tor-browser-macos-15.0.17.dmg.asc: PGP signature Signature (old)
$ gpg --verify tor-browser-macos-*.asc
[...]
gpg: Can't check signature: No public key
$ gpg --auto-key-locate nodefault,wkd --locate-keys torbrowser@torproject.org
gpg: key 0x4E2C6E8793298290: public key "Tor Browser Developers (signing key) <torbrowser@torproject.org>" imported
gpg: Total number processed: 1
gpg: imported: 1
pub rsa4096/0x4E2C6E8793298290 2014-12-15 [C] [expires: 2027-07-15]
Key fingerprint = EF6E 286D DA85 EA2A 4BA7 DE68 4E2C 6E87 9329 8290
uid [ unknown] Tor Browser Developers (signing key) <torbrowser@torproject.org>
sub rsa4096/0x157432CF78A65729 2024-07-15 [S] [expires: 2026-10-26]
Key fingerprint = CAAE 408A EBE2 288E 96FC 5D5E 1574 32CF 78A6 5729
$ gpg --verify tor-browser-macos-*.asc
gpg: assuming signed data in 'tor-browser-macos-15.0.17.dmg'
gpg: Signature made Sun Jun 28 15:35:20 2026 PDT
gpg: using RSA key CAAE408AEBE2288E96FC5D5E157432CF78A65729
gpg: Good signature from "Tor Browser Developers (signing key) <torbrowser@torproject.org>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg: There is no indication that the signature belongs to the owner.
Primary key fingerprint: EF6E 286D DA85 EA2A 4BA7 DE68 4E2C 6E87 9329 8290
Subkey fingerprint: CAAE 408A EBE2 288E 96FC 5D5E 1574 32CF 78A6 5729Make sure Good signature from "Tor Browser Developers (signing key) <torbrowser@torproject.org>" appears in the output. The warning is expected, as the key has not been personally verified and added to a trusted keyring.
See How can I verify Tor Browser's signature? for more information.
To finish installing Tor Browser, open the disk image and drag it to the Applications folder, or:
hdiutil mount TorBrowser-8.0.4-osx64_en-US.dmg
cp -r /Volumes/Tor\ Browser/Tor\ Browser.app/ ~/Applications/Verify the application was signed by The Tor Project's Apple Developer ID MADPSAYN6T, using the spctl -a -v and/or pkgutil --check-signature commands:
$ spctl -a -vv ~/Applications/Tor\ Browser.app
/Users/user1/Applications/Tor Browser.app: accepted
source=Notarized Developer ID
origin=Developer ID Application: The Tor Project, Inc (MADPSAYN6T)
$ pkgutil --check-signature ~/Applications/Tor\ Browser.app
Package "Tor Browser.app":
Status: signed by a certificate trusted by macOS
Certificate Chain:
1. Developer ID Application: The Tor Project, Inc (MADPSAYN6T)
Expires: 2028-10-11 17:57:46 +0000
SHA256 Fingerprint:
76 3C 89 02 ED CB AD 8E 59 86 1E 93 D3 05 5B 28 F9 04 0C 96 03 8B
16 28 9F 38 64 ED 53 45 B4 DA
------------------------------------------------------------------------
2. Developer ID Certification Authority
Expires: 2031-09-17 00:00:00 +0000
SHA256 Fingerprint:
F1 6C D3 C5 4C 7F 83 CE A4 BF 1A 3E 6A 08 19 C8 AA A8 E4 A1 52 8F
D1 44 71 5F 35 06 43 D2 DF 3A
------------------------------------------------------------------------
3. Apple Root CA
Expires: 2035-02-09 21:40:36 +0000
SHA256 Fingerprint:
B0 B1 73 0E CB C7 FF 45 05 14 2C 49 F1 29 5E 6E DA 6B CA ED 7E 2C
68 C5 BE 91 B5 A1 10 01 F0 24The command codesign can also be used to examine an application's code signature:
$ codesign -dvv ~/Applications/Tor\ Browser.app
Executable=/Users/user1/Applications/Tor Browser.app/Contents/MacOS/firefox
Identifier=org.torproject.torbrowser
Format=app bundle with Mach-O universal (x86_64 arm64)
CodeDirectory v=20500 size=805 flags=0x10000(runtime) hashes=14+7 location=embedded
Signature size=9054
Authority=Developer ID Application: The Tor Project, Inc (MADPSAYN6T)
Authority=Developer ID Certification Authority
Authority=Apple Root CA
Timestamp=Jun 28, 2026 at 14:01:57
Notarization Ticket=stapled
Info.plist entries=27
TeamIdentifier=MADPSAYN6T
Runtime Version=15.5.0
Sealed Resources version=2 rules=13 files=208
Internal requirements count=1 size=188To view full certificate details for a signed application, extract with codesign and decode with openssl:
$ codesign -d --extract-certificates ~/Applications/Tor\ Browser.app
Executable=/Users/user1/Applications/Tor Browser.app/Contents/MacOS/firefox
$ file codesign*
codesign0: Certificate, Version=3
codesign1: Certificate, Version=3
codesign2: Certificate, Version=3 Certificate, Version=02
$ openssl x509 -inform der -in codesign0 -subject -issuer -startdate -enddate -noout
subject= /UID=MADPSAYN6T/CN=Developer ID Application: The Tor Project, Inc (MADPSAYN6T)/OU=MADPSAYN6T/O=The Tor Project, Inc/C=US
issuer= /CN=Developer ID Certification Authority/OU=G2/O=Apple Inc./C=US
notBefore=Oct 11 17:57:47 2023 GMT
notAfter=Oct 11 17:57:46 2028 GMT
$ openssl x509 -inform der -in codesign0 -fingerprint -noout
SHA256 Fingerprint=76:3C:89:02:ED:CB:AD:8E:59:86:1E:93:D3:05:5B:28:F9:04:0C:96:03:8B:16:28:9F:38:64:ED:53:45:B4:DATor traffic can be obfuscated using a pluggable transport. This can be done by setting up a relay or using an existing bridge.
The Tor network provides anonymity, which is not necessarily the same as privacy. The network does not defend against a global observer capable of traffic analysis and correlation. See also Seeking Anonymity in an Internet Panopticon (pdf) and Traffic Correlation on Tor by Realistic Adversaries (pdf).
See Tor Protocol Specification for more information.
Also see Invisible Internet Project (I2P) and its Tor comparison.
When choosing a VPN service or self-hosting, be sure to validate the protocols, key exchange algorithms, authentication mechanisms, and type of encryption used. Some protocols, such as PPTP, should be avoided in favor of OpenVPN or Linux-based Wireguard on a Linux VM or via a set of cross platform tools.
Some VPN clients may send traffic over the next available network interface when the connection is interrupted or disconnected. See scy/8122924 for an example on how to allow traffic only over VPN.
See guides to set up an IPsec VPN on a virtual machine (hwdsl2/setup-ipsec-vpn) or a Docker container (hwdsl2/docker-ipsec-vpn-server).
It may be worthwhile to consider the geographical location of the VPN provider. See further discussion in issue 114.
Also see this technical overview of the macOS built-in VPN L2TP/IPsec and IKEv2 client.
PGP is a standard for signing and encrypting data end-to-end, especially email.
GPG (GNU Privacy Guard) is a GPL-licensed, open-source program compliant with the PGP standard.
GPG is used to verify signatures of software you download and install, as well as symmetrically or asymmetrically encrypt files and text.
Install from Homebrew with brew install gnupg or using GPG Suite.
Download gpg.conf to use recommended settings:
curl -o ~/.gnupg/gpg.conf https://raw.githubusercontent.com/drduh/YubiKey-Guide/master/config/gpg.confSee drduh/YubiKey-Guide to generate and manage GPG credentials.
Email is not designed to provide strong privacy by default: message content may be retained by service providers, copied to recipients' mailboxes, forwarded, or exposed through account compromise. Metadata (including recipient, subject, timestamps, and mail server information) generally remains visible even when message content is encrypted.
Thunderbird is a free and open-source email client with standard IMAP, POP, CalDAV, and CardDAV support. It is a suitable choice for accessing and retaining mail locally rather than depend exclusively on a provider's remote server.
Thunderbird includes support for OpenPGP email encryption, which can protect message content and provide cryptographic signatures. Always verify public-key fingerprints through an independent channel before relying on a key for sensitive communication.
The archived messages feature can move messages out of remote mail servers to a Local Folder, improving privacy.
XMPP is an open protocol developed by the IETF that supports cross-platform, federated messaging. There are many client options. Consider using one of the browser-based clients to take advantage of the browser's sandbox.
Depending on the provider, you might not need anything other than a username and password to set up an account.
XMPP is not end-to-end encrypted (E2EE) by default - use OMEMO with a supported client.
Signal is a popular E2EE messenger whose double-ratchet protocol is used by many other applications including WhatsApp, Google Messages, and Facebook Messenger.
To use the Signal desktop app, Signal must first be installed on a phone.
iMessage is Apple's first-party messenger. It requires an Apple Account to use.
Enable Contact Key Verification and verify contacts.
iMessage can be used with either a phone number or an email.
Warning
By default, iCloud backup is enabled, which stores copies of message encryption keys on Apple's servers without E2EE. Either disable iCloud backup or enable Advanced Data Protection to prevent this. Remind messaging recipients to do the same.
See Methods of malware persistence on Mac OS X (pdf) and Malware Persistence on OS X Yosemite to learn about how basic malware functions.
Also check out Hacking Team malware for macOS: root installation for MacOS, Support driver for Mac Agent and RCS Agent for Mac, which is a good example of advanced malware capabilities. For more, see A Brief Analysis of an RCS Implant Installer and reverse.put.as
Running applications from the App Store or that are Notarized by Apple may reduce malware risk: Apple performs an automated scan on notarized applications and App Store requires a review process.
Otherwise, obtain software from trusted sources, such as from the developer's website or GitHub. Always make sure that the browser/terminal is using HTTPS.
Check if a program uses App Sandbox:
codesign -dvvv --entitlements - /path/to/application.appWith App Sandbox enabled, output will include:
[Key] com.apple.security.app-sandbox
[Value]
[Bool] trueAlternatively, check Activity Monitor while the application is running and add the "Sandbox" column.
App Store software is required to use App Sandbox. Applications such as Google Chrome use their own sandbox and might not use App Sandbox.
Note
Sandboxing limits an application's default access, but entitlements and user-granted permissions can expand access.
Check if a program uses the Hardened Runtime before running it using the following command:
codesign --display --verbose /path/to/application.appIf Hardened Runtime is enabled, flags=0x10000(runtime) will appear in output.
Activity Monitor has the option to display a "Restricted" column which indicates a program is restricted from injecting code via macOS's dynamic linker.
The Hardened Runtime is a prerequisite for notarization of distributed apps.
To scan files and applications, consider uploading them to VirusTotal, keeping in mind this makes them publicly-viewable.
macOS includes built-in antivirus software called XProtect, which runs in the background and updates signatures used to detect malware automatically. If malware is detected, XProtect attempts to remove and quarantine it.
Applications such as BlockBlock or hazcod/maclaunch might help prevent or detect persistent malware.
Antivirus software may act as a "double-edged sword": capable of countering common, "garden-variety" malware, but having potential to increase attack surface with system-level privileges. They may also send telemetry and malware samples, increasing privacy risk.
See Sophail: Applied attacks against Antivirus (pdf), Analysis and Exploitation of an ESET Vulnerability, Popular Security Software Came Under Relentless NSA and GCHQ Attacks, and How Israel Caught Russian Hackers Scouring the World for U.S. Secrets.
Gatekeeper verifies software notarization and provenance.
Gatekeeper warns when opening an application without notarization. It can be bypassed by selecting the application listed in System Settings > Privacy & Security after a failed attempt.
To verify System Integrity Protection is enabled, use the command csrutil status, which should return: System Integrity Protection status: enabled. Otherwise, enable SIP using Recovery Mode.
macOS attaches metadata (APFS extended attributes) to files.
Metadata attributes can be viewed and removed with the mdls and xattr commands.
Other metadata and artifacts may be found in the directories including, but not limited to, ~/Library/Preferences/, ~/Library/Containers/<APP>/Data/Library/Preferences, /Library/Preferences, some of which is detailed below.
~/Library/Preferences/com.apple.sidebarlists.plist contains historical list of volumes attached. To clear it, use the command /usr/libexec/PlistBuddy -c "delete :systemitems:VolumesList" ~/Library/Preferences/com.apple.sidebarlists.plist
/Library/Preferences/com.apple.Bluetooth.plist contains Bluetooth metadata, including device history. If Bluetooth is not used, the metadata can be cleared with:
sudo defaults delete /Library/Preferences/com.apple.Bluetooth.plist DeviceCache
sudo defaults delete /Library/Preferences/com.apple.Bluetooth.plist IDSPairedDevices
sudo defaults delete /Library/Preferences/com.apple.Bluetooth.plist PANDevices
sudo defaults delete /Library/Preferences/com.apple.Bluetooth.plist PANInterfaces
sudo defaults delete /Library/Preferences/com.apple.Bluetooth.plist SCOAudioDevices/var/spool/cups contains the CUPS printer job cache. To clear it, use the commands:
sudo rm -rfv /var/spool/cups/c0*
sudo rm -rfv /var/spool/cups/tmp/*
sudo rm -rfv /var/spool/cups/cache/job.cache*To clear the list of iOS devices connected, use:
sudo defaults delete /Users/$USER/Library/Preferences/com.apple.iPod.plist "conn:128:Last Connect"
sudo defaults delete /Users/$USER/Library/Preferences/com.apple.iPod.plist Devices
sudo defaults delete /Library/Preferences/com.apple.iPod.plist "conn:128:Last Connect"
sudo defaults delete /Library/Preferences/com.apple.iPod.plist Devices
sudo rm -rfv /var/db/lockdown/*Quicklook thumbnail data can be cleared using the qlmanage -r cache command, but this writes to the file resetreason in the Quicklook directories, and states that the Quicklook cache was manually cleared. Disable the thumbnail cache with qlmanage -r disablecache
It can also be cleared by getting the directory names with getconf DARWIN_USER_CACHE_DIR and sudo getconf DARWIN_USER_CACHE_DIR, then removing them:
rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/exclusive
rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/index.sqlite
rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/index.sqlite-shm
rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/index.sqlite-wal
rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/resetreason
rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/thumbnails.dataSimilarly, for the root user:
sudo rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/thumbnails.fraghandler
sudo rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/exclusive
sudo rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/index.sqlite
sudo rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/index.sqlite-shm
sudo rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/index.sqlite-wal
sudo rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/resetreason
sudo rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/thumbnails.data
sudo rm -rfv $(getconf DARWIN_USER_CACHE_DIR)/com.apple.QuickLook.thumbnailcache/thumbnails.fraghandlerAlso see 'quicklook' cache may leak encrypted data.
To clear Finder preferences:
defaults delete ~/Library/Preferences/com.apple.finder.plist FXDesktopVolumePositions
defaults delete ~/Library/Preferences/com.apple.finder.plist FXRecentFolders
defaults delete ~/Library/Preferences/com.apple.finder.plist RecentMoveAndCopyDestinations
defaults delete ~/Library/Preferences/com.apple.finder.plist RecentSearches
defaults delete ~/Library/Preferences/com.apple.finder.plist SGTRecentFileSearchesAdditional diagnostic files may be found in the following directories - but caution should be taken before removing any, as it may break logging or cause other issues:
/var/db/CoreDuet/
/var/db/diagnostics/
/var/db/systemstats/
/var/db/uuidtext/
/var/log/DiagnosticMessages/
macOS stores Wi-Fi connection metadata (including credentials) in NVRAM. To clear it, use the following commands:
sudo nvram -d 36C28AB5-6566-4C50-9EBD-CBB920F83843:current-network
sudo nvram -d 36C28AB5-6566-4C50-9EBD-CBB920F83843:preferred-networks
sudo nvram -d 36C28AB5-6566-4C50-9EBD-CBB920F83843:preferred-countmacOS may collect sensitive information about what you type, even if user dictionary and suggestions are off. To remove them, and prevent them from being created again, use the following commands:
rm -rfv "~/Library/LanguageModeling/*" "~/Library/Spelling/*" "~/Library/Suggestions/*"
chmod -R 000 ~/Library/LanguageModeling ~/Library/Spelling ~/Library/Suggestions
chflags -R uchg ~/Library/LanguageModeling ~/Library/Spelling ~/Library/SuggestionsQuickLook application support metadata can be cleared and locked with the following commands:
rm -rfv "~/Library/Application Support/Quick Look/*"
chmod -R 000 "~/Library/Application Support/Quick Look"
chflags -R uchg "~/Library/Application Support/Quick Look"Document revision metadata is stored in /.DocumentRevisions-V100 and can be cleared and locked with the following commands - caution should be taken as this may break some core Apple applications:
sudo rm -rfv /.DocumentRevisions-V100/*
sudo chmod -R 000 /.DocumentRevisions-V100
sudo chflags -R uchg /.DocumentRevisions-V100Saved application state metadata may be cleared and locked with the following commands:
rm -rfv ~/Library/Saved\ Application\ State/*
rm -rfv ~/Library/Containers/<APPNAME>/Data/Library/Saved\ Application\ State
chmod -R 000 ~/Library/Saved\ Application\ State/
chmod -R 000 ~/Library/Containers/<APPNAME>/Data/Library/Saved\ Application\ State
chflags -R uchg ~/Library/Saved\ Application\ State/
chflags -R uchg ~/Library/Containers/<APPNAME>/Data/Library/Saved\ Application\ StateAutosave metadata can be cleared and locked with the following commands:
rm -rfv "~/Library/Containers/<APP>/Data/Library/Autosave Information"
rm -rfv "~/Library/Autosave Information"
chmod -R 000 "~/Library/Containers/<APP>/Data/Library/Autosave Information"
chmod -R 000 "~/Library/Autosave Information"
chflags -R uchg "~/Library/Containers/<APP>/Data/Library/Autosave Information"
chflags -R uchg "~/Library/Autosave Information"The Siri analytics database, which is created even if the Siri launch agent is disabled, can be cleared and locked with the following commands:
rm -rfv ~/Library/Assistant/SiriAnalytics.db
chmod -R 000 ~/Library/Assistant/SiriAnalytics.db
chflags -R uchg ~/Library/Assistant/SiriAnalytics.dbMedia played in QuickTime Player can be found in:
~/Library/Containers/com.apple.QuickTimePlayerX/Data/Library/Preferences/com.apple.QuickTimePlayerX.plistAdditional metadata may exist in the following files:
~/Library/Containers/com.apple.appstore/Data/Library/Preferences/com.apple.commerce.knownclients.plist
~/Library/Preferences/com.apple.commerce.plist
~/Library/Preferences/com.apple.QuickTimePlayerX.plistThe Passwords app creates secure credentials. It supports passkeys - credentials which are more resilient to phishing.
KeePassXC is an open-source, cross-platform password manager to consider. It supports strong authentication with compatible hardware tokens and a browser extension for entering credentials automatically.
Memorable passwords can be created with Diceware.
Ensure online accounts have multi-factor authentication enabled. The strongest form of multi-factor authentication is WebAuthn, followed by TOTP/HOTP (commonly implemented by authenticator apps); SMS-based codes are weakest since they rely on the service provider.
YubiKey is a popular authentication token. It can also store cryptographic keys for encryption and authentication - see drduh/YubiKey-Guide.
GnuPG can also manage passwords and other encrypted files - see drduh/Purse and drduh/pwd.sh.
Encrypt files locally before backing them up to external media or online services.
Follow the 3-2-1 backup model: keep 3 copies (original and two backups); keep backups on 2 different media types; store 1 backup copy remotely.
Time Machine is the built-in tool for handling backups on macOS. Use an external drive or network storage to create encrypted backups.
GnuPG can be used with a password or public key, with the private key stored on YubiKey.
Compress and encrypt a directory using a password:
tar zcvf - ~/Downloads | gpg -c > ~/Downloads/backup-$(date +%F-%H%M).tar.gz.gpgDecrypt and decompress the directory:
gpg -o ~/Downloads/decrypted-backup.tar.gz -d ~/Downloads/backup-*.tar.gz.gpg
tar zxvf ~/Downloads/decrypted-backup.tar.gzEncrypted volumes can be created using Disk Utility or hdiutil:
hdiutil create ~/Downloads/encrypted.dmg -encryption -size 50M -volname "secretStuff"
hdiutil mount ~/Downloads/encrypted.dmg
cp -v ~/Documents/passwords.txt /Volumes/secretStuff
hdiutil eject /Volumes/secretStuffTresorit and restic may also be of interest.
Wi-Fi networks continuously broadcast a service set identifier (SSID) which allows devices to passively scan for previously-connected networks. Hidden networks do not transmit an SSID and devices send a probe with the SSID to connect, which can reveal metadata. Avoid using hidden networks.
Set a private Wi-Fi address to reduce network tracking.
Set wireless network security to WPA3. Follow Apple guidance to set recommended settings for routers and access points.
For outgoing SSH connections, use hardware or password-protected keys, set up remote hosts and consider hashing them for added privacy. See drduh/config/ssh_config for recommended client options.
An SSH tunnel can securely route traffic through another computer, similar to a VPN.
To use Privoxy running on a remote host on port 8118:
ssh -C -L 5555:127.0.0.1:8118 you@remote-host.tld
sudo networksetup -setwebproxy "Wi-Fi" 127.0.0.1 5555
sudo networksetup -setsecurewebproxy "Wi-Fi" 127.0.0.1 5555Or to use an SSH connection as a SOCKS proxy:
ssh -NCD 3000 you@remote-host.tldBy default, macOS does not have Remote Login (SSH server) enabled.
To enable SSH and allow incoming connections, use System Settings > General > Sharing or the command:
sudo launchctl load -w /System/Library/LaunchDaemons/ssh.plistDisable password authentication and consider further hardening the SSH server configuration. See drduh/config/sshd_config for recommended options.
Confirm the SSH server is running:
sudo lsof -Pni TCP:22Do not leave the computer unattended in unsafe locations. A skilled attacker with unsupervised physical access could install a hardware keylogger to record keystrokes, including passwords. Using a Mac with a built-in keyboard or a bluetooth keyboard makes this more difficult as many off-the-shelf versions of this attack are designed to be plugged in between a USB keyboard and the computer.
To protect against physical theft during use, use an anti-forensic tool such as buskill/buskill-app or Lennolium/swiftGuard (updated usbkill, with graphical user interface). All respond to USB events and can immediately shut the computer down if the device is physically separated or an unauthorized device is connected.
Consider purchasing a privacy screen/filter for use in public.
Nail polish and tamper-evidence seals can be applied to components to detect tampering.
Monitor system logs with Console or the /usr/bin/log stream command.
To show log entries generated by the audioaccessoryd process during the last hour:
/usr/bin/log show \
--last 1h \
--predicate 'process == "audioaccessoryd"' \
--style compactmacOS has a powerful OpenBSM (Basic Security Module) auditing capability, which can be used to monitor processes, network activity, etc.
To tail audit logs, use the praudit utility:
$ sudo praudit -l /dev/auditpipe
header,201,11,execve(2),0,Thu Sep 1 12:00:00 2015, + 195 msec,exec arg,/Applications/.evilapp/rootkit,path,/Applications/.evilapp/rootkit,path,/Applications/.evilapp/rootkit,attribute,100755,root,wheel,16777220,986535,0,subject,drduh,root,wheel,root,wheel,412,100005,50511731,0.0.0.0,return,success,0,trailer,201,
header,88,11,connect(2),0,Thu Sep 1 12:00:00 2015, + 238 msec,argument,1,0x5,fd,socket-inet,2,443,173.194.74.104,subject,drduh,root,wheel,root,wheel,326,100005,50331650,0.0.0.0,return,failure : Operation now in progress,4354967105,trailer,88
header,111,11,OpenSSH login,0,Thu Sep 1 12:00:00 2015, + 16 msec,subject_ex,drduh,drduh,staff,drduh,staff,404,404,49271,::1,text,successful login drduh,return,success,0,trailer,111,See the manual pages for audit, praudit, audit_control and other files in /etc/security
Although man audit says the -s flag will synchronize the audit configuration, it appears necessary to reboot for changes to take effect.
See articles on ilostmynotes.blogspot.com and derflounder.wordpress.com for more information.
System Integrity Protection interferes with DTrace, so it is not possible to use it in recent macOS versions without disabling SIP.
iosnoopmonitors disk I/Oopensnoopmonitors file opensexecsnoopmonitors processeserrinfomonitors failed system callsdtrussmonitors all system calls
See man -k dtrace for more information.
List running processes with Activity Monitor or the ps -ef command.
List open network connections:
sudo lsof -PniList the contents of various network-related data structures:
sudo netstat -atlnWireshark can be used from the command line with tshark.
Monitor DNS:
tshark -Y "dns.flags.response == 1" -Tfields \
-e frame.time_delta \
-e dns.qry.name \
-e dns.a \
-Eseparator=,Monitor HTTP:
tshark -Y "http.request or http.response" -Tfields \
-e ip.dst \
-e http.request.full_uri \
-e http.request.method \
-e http.response.code \
-e http.response.phrase \
-Eseparator=/sMonitor x509/TLS certificates:
tshark -Y "ssl.handshake.certificate" -Tfields \
-e ip.src \
-e x509sat.uTF8String \
-e x509sat.printableString \
-e x509sat.universalString \
-e x509sat.IA5String \
-e x509sat.teletexString \
-Eseparator=/s -Equote=dDisable Diagnostics & Usage Data.
Disable crash reporter (the dialog which appears after an application crashes and prompts to report the problem to Apple):
defaults write com.apple.CrashReporter DialogType noneUse QuickTime Player, the built-in media application, for playing music and video files. It uses App Sandbox, Hardened Runtime, and benefits from the Signed System Volume as part of the base system.
Manage default file handlers to reduce risk of opening dangerous types.
Change the default application used to open shell script files.
In Finder, locate and select any .sh file, right-click on it and select Get Info or press Command + I. In the "Open with" section, select TextEdit from the dropdown menu. If it is not listed, select "Other..." and Applications > TextEdit.app. Select "Change All..." and confirm by selecting Continue.
From then on, double-clicking any .sh file will open it in TextEdit instead of Terminal.
Set the screen to lock as soon as the screensaver starts:
defaults write com.apple.screensaver askForPassword -int 1
defaults write com.apple.screensaver askForPasswordDelay -int 0Expose hidden files and Library folder in Finder:
defaults write com.apple.finder AppleShowAllFiles -bool true
chflags nohidden ~/LibraryShow all filename extensions (so that "Evil.jpg.app" cannot masquerade easily).
defaults write NSGlobalDomain AppleShowAllExtensions -bool trueDo not default to saving documents to iCloud:
defaults write NSGlobalDomain NSDocumentSaveNewDocumentsToCloud -bool falseSet a custom umask:
sudo launchctl config user umask 077Reboot, then create a file/directory and verify permissions (macOS default allows 'group/other' read access):
$ ls -ld umask*
drwx------@ 2 user1 staff 64 Jul 26 12:00 umask.dir
-rw-------@ 1 user1 staff 32 Jul 26 12:00 umask.txtEnable secure keyboard entry in Terminal (this may interfere with applications such as TextExpander).
Disable Bonjour multicast advertisements (this also disables AirPlay and AirPrint features):
sudo defaults write /Library/Preferences/com.apple.mDNSResponder NoMulticastAdvertisements -bool YESDisable Handoff and Bluetooth features.
macOS comes with this line in /etc/sudoers:
Defaults env_keep += "HOME MAIL"This stops sudo from changing the HOME variable when privileges are elevanted. This means it will execute as root the zsh dotfiles in the non-root user's home directory when running sudo zsh. It is advisable to comment this line out to avoid a potential way for malware or a local attacker to escalate root privileges.
To retain the convenience of the root user having a non-root user's home directory, append an export line to /var/root/.zshrc, e.g.:
export HOME=/Users/user1- CISOfy/lynis - Cross-platform security auditing tool and assists with compliance testing and system hardening.
- Zentral - A log and configuration server for osquery. Run audit and probes on inventory, events, logfiles, combine with point-in-time alerting. A full Framework and Django web server build on top of the elastic stack (formerly known as ELK stack).
- osquery - Can be used to retrieve low-level system information. Users can write SQL queries to retrieve system information.
- Pareto Security - A MenuBar app to automatically audit your Mac for basic security hygiene.
- Apple Open Source
- CIS Benchmarks
- EFF Surveillance Self-Defense Guide
- iOS, The Future Of macOS, Freedom, Security And Privacy In An Increasingly Hostile Global Environment
- Patrick Wardle's Objective-See blog
- Reverse Engineering macOS blog
- Reverse Engineering Resources
- iCloud security and privacy overview
- Malwarebytes Blog