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System Hardening Checklist

About this System Hardening Checklist Page
Support Status stable
Difficulty easy
Maintainer torjunkie
Support Support

Introduction[edit]

It is possible for users to significantly harden their Whonix and/or host platform and improve the chances of successful, anonymous activity. This depends upon a user's skill set, motivation and available hardware. The checklist below is intended to provide a quick overview of important issues, categorized by difficulty level - easy, moderate, difficult and expert.

Easy[edit]

Anonymous Blogging, Posting, Chat, Email and File Sharing[edit]

  • To remain anonymous, follow all the Whonix recommendations to minimize threats of keyboard/mouse biometrics, stylometric analysis and other covert channels.
  • Remove metadata from documents, pictures, videos or other files before uploading them to the Internet.
  • Think twice before sharing "anonymous" photos due to unique embedded noise signatures that have no known countermeasures.
  • Be careful sharing anonymous documents. Digital watermarks with embedded covert data are robust, so run documents through Optical Character Recognition (OCR) before sharing the output.
  • Utilize OnionShare to share files securely and anonymously over the Tor network. [1]

Disabling and Minimizing Hardware Risks[edit]

File Handling[edit]

  • In File Manager, disable previews of files from untrusted sources. Change file preferences in the TemplateVM's File Manager so future AppVMs inherit this feature.
  • Files received or downloaded from untrusted sources (the internet, via email etc.) should not be opened in a trusted VM. Instead, open them in a DisposableVM: Right-click -> Open In DisposableVM
  • Untrusted PDFs should be opened in a DisposableVM or converted into a trusted (sanitized) PDF to prevent exploitation of the PDF reader and potential infection of the VM.

Mandatory Access Control[edit]

  • Enable all available apparmor profiles in the Whonix-Workstation and Whonix-Gateway TemplateVMs.
  • Enable seccomp on Whonix-Gateway (sys-whonix ProxyVM).

Passwords and Logins[edit]

  • Use strong, unique and random passwords for all online accounts, system logins and encryption / decryption purposes to prevent the feasibility of brute-forcing attacks.
  • Use a trusted password manager, so hundreds of different passwords can be kept stored in an encrypted password database, protected by one strong master password. [4]
  • For high-entropy passwords, consider using Diceware passphrases. [5]
  • In Qubes-Whonix, store all login credentials and passwords in an offline vault VM (preferably with KeyPassX) and securely cut and paste them into the Tor Browser. [6]
  • Read and follow all the principles for stronger passwords.

Secure Downloads[edit]

  • Download Internet files securely using scurl instead of wget from the command line.
  • When downloading with Tor Browser, prevent SSLstrip attacks by typing https:// links directly into the URL / address bar.
  • Prefer onion services file downloads, which provide greater security and anonymity than https.

Secure Qubes Operation[edit]

Secure Software Installation[edit]

Tor Browser Series and Settings[edit]

VirtualBox[edit]

Moderate[edit]

Create a USB Qube[edit]

Host Operating System Distribution[edit]

  • For a truly private operating system, install GNU/Linux on the host. [16]
  • The Debian distribution is recommended by Whonix as providing a reasonable balance of security and usability.

Host Operating System Hardening[edit]

All Platforms[edit]

Non-Qubes-Whonix Only[edit]

  • Harden the host Debian Linux OS.

Networking[edit]

All Platforms[edit]

  • If possible, use a dedicated network connection (LAN, WiFi etc.) that is not shared with other potentially compromised computers.
  • If using a shared network via a common cable modem/router or ADSL router, configure a de-militarized zone (perimeter network). [17]
  • Test the LAN's router/firewall with either an internet port scanning service or preferably a port scanning application from an external IP address.
  • Change the default administration password on the router to a unique, random, and suitably long Diceware passphrase to prevent bruteforcing attacks.
  • WiFi users should default to the WPA2-AES standard which provides the safest protocol and strongest encryption. [18]
  • Follow all other Whonix recommendations to lock down the router.

Qubes-Whonix Only[edit]

  • Prefer the Debian Template for networking (sys-net and sys-firewall) since it is minimal in nature and does not "ping home", unlike the Fedora Template. [19]
  • Consider using customized minimal templates for NetVMs to reduce the attack surface.
  • For greater security, higher performance and a lower resource footprint, consider using an experimental MirageOS-based unikernel firewall that can run as a QubesOS ProxyVM.

Newer Kernels[edit]

Sandboxing[edit]

  • Use Firejail to restrict Tor Browser, Firefox-ESR, VLC and other regularly used applications. [21]

Spoof MAC Addresses[edit]

  • In Qubes-Whonix, follow these steps to spoof the MAC address on the Debian or Fedora TemplateVM used for network connections.
  • In Non-Qubes-Whonix, follow these steps to spoof the MAC address of the network card on a Linux, Windows or macOS host.

Time Stamps and NTP Clients[edit]

Tor Settings[edit]

Whonix VM Security[edit]

Difficult[edit]

Anti-Evil Maid[edit]

  • If a Trusted Platform Module is available, use AEM protection to attest that only desired (trusted) components are loaded and executed during the system boot. [27]

Chaining Anonymizing Tunnels[edit]

DisposableVMs[edit]

  • Run all instances of Tor Browser in a DisposableVM which is preferably uncustomized to resist fingerprinting. [28]
  • Configure each ServiceVM as a Static DisposableVM to mitigate the threat from persistent malware accross VM reboots. [29]

Email[edit]

All Platforms[edit]

Qubes-Whonix Only[edit]

  • Use split-GPG for email to reduce the risk of key theft used for encryption / decryption and signing.
  • Create an AppVM that is exclusively used for email and change the VM's firewall settings to only allow network connections to the email server and nothing else ("Deny network access except...").
  • Only open untrusted email attachments in a DisposableVM to prevent possible infection.

Flash the Router with Opensource Firmware[edit]

Multi-Factor User Authentication[edit]

  • Utilize a Yubikey to enhance the security of Qubes user authentication, mitigate the risk of password snooping, and to improve USB keyboard security.

Whitelisting Tor Traffic[edit]

Expert[edit]

Disable Intel ME Blobs[edit]

Install Libreboot[edit]

  • Libreboot is a free, opensource BIOS or UEFI replacement (firmware) that initializes the hardware and starts the bootloader for your OS.

Physical Isolation[edit]

Footnotes[edit]

  1. Whonix 14 and later releases.
  2. This applies to both Intel and AMD architecture.
  3. While this may introduce new vulnerabilities, this is objectively better than running a system that is vulnerable to known attacks.
  4. For greater security, store the password manager off-line.
  5. To estimate strength, an 8-word Diceware passphrase provides ~90 bits of entropy, while a 10-word passphrase provides ~128 bits of entropy.
  6. For greater safety, copy something else into the clipboard after pasting so the password is purged and cannot be accidentally pasted elsewhere.
  7. From Whonix 14, the Whonix and Debian repositories are set to onion mirrors by default.
  8. Selfrando provides a significant security improvement over standard address space layout randomization (ASLR) present in Tor Browser and other browsers. Selfrando is incompatible with grsecurity kernels. Due to this resolved bug, Selfrando has been integrated into the alpha series from 7.0a4 onward.
  9. The "hardened" Tor Browser series has been deprecated, see: https://trac.torproject.org/projects/tor/ticket/21912
  10. Following the official release of the v8.0+ Tor Browser series (based on Firefox 60 ESR), the stable and alpha Tor Browser versions both have a native sandbox.
  11. This may affect usability and proper functioning on some websites.
  12. This is more secure, but increases the user's fingerprinting risk due to selective use of Javascript.
  13. Thereby circumventing any possible future problems, like the breakage of Whonix.
  14. A USB qube is automatically created as of Qubes R4.0
  15. USB keyboards and mice expose dom0 to attacks, and all USB devices are potential side channel attack vectors.
  16. Windows and macOS are surveillance platforms that do not respect user freedom or privacy.
  17. This restricts Whonix-Gateway accessibility to/from other nodes on the network e.g. printers, phones and laptops.
  18. Do not rely on WiFi Protected Set-up (WPS), which has major security flaws.
  19. https://forums.whonix.org/t/disable-sys-net-pings-to-fedoraproject-org/1952
  20. This recommendation comes with a warning: cutting-edge kernels may destabilize the system or cause boot failures.
  21. Previously The Tor Project's alpha sandbox was recommended to restrict Tor Browser, but the project has unfortunately been abandoned.
  22. Such as system information, host time, system uptime, and fingerprinting of devices behind a router.
  23. This prevents time-related attack vectors which rely on leakage of the host time.
  24. Via creation of a new Whonix-Gateway (sys-whonix).
  25. For example, Whonix users residing in China.
  26. This is useful when testing later Whonix releases to stymie deanonymization attempts by advanced adversaries, or when creating an identical backup that does not share any other persistent data, except for Tor state and custom torrc options.
  27. Unauthorized modifications to BIOS or the boot partition will be notified.
  28. This is safe in Qubes R4, but privacy issues are unresolved in Qubes R3.2
  29. Users may configure sys-net, sys-firewall and sys-usb as static DisposableVMs. This option is only available for Qubes R4 users.
  30. Reminder: The Subject: line and other header fields are not encrypted in the current configuration.
  31. This provides an additional fail-safe to protect from accidental clearnet leaks that might arise from hypothetical Whonix bugs, but does not address potential Qubes ProxyVM leaks.
  32. https://github.com/rustybird/corridor
  33. Using two different computers and virtualization is one of the most secure configurations available, but may be less secure than Qubes' approach (software compartmentalization).

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