Review of Mullvad VPN (x41-dsec.de)

Article summary

X41 performed a white box penetration test on the Mullvad VPN application, discovering six vulnerabilities, including signal handler issues and potential deanonymization attacks. The vulnerabilities were found in the Android, iOS, and Desktop versions of the app. Despite these findings, the report concludes that the Mullvad VPN application has a high security level and is well-positioned to protect against threats. The vulnerabilities have been addressed by Mullvad VPN AB.

Main themes

• VPN security
• Signal handling
• Penetration testing
• Deanonymization attacks
• Secure coding practices

What commenters say

• Safe signal handling is extremely difficult to achieve, even with careful coding practices, due to the complexity of signal delivery and handling in UNIX systems.
• Using a dedicated thread to handle signals or setting a global variable value are considered best practices for handling signals, but have limitations.
• Some commenters argue that Rust's borrow checker can help write safe signal handlers, while others believe that signal handling is inherently difficult and error-prone.
• Randomizing virtual IP addresses for each user on each connection may not be an effective mitigation for deanonymization attacks and could potentially make the situation worse.
• The use of monads or other functional programming concepts may help improve the safety and reliability of signal handling code, but this approach has its own limitations and challenges.
• Some commenters believe that the title of the article is misleading, as it refers to the audit of the VPN application rather than the VPN service itself.
• The discussion highlights the trade-offs between security, anonymity, and usability in VPN design and implementation, with no clear consensus on the best approach.