CVE-2021-39246 Explained : Impact and Mitigation
Learn about CVE-2021-39246, an issue in Tor Browser allowing a correlation attack that compromises privacy when visiting v2 onion addresses. Find out the impacted versions and steps to mitigate the vulnerability.
Tor Browser through 10.5.6 and 11.x allows a correlation attack compromising privacy of visits to v2 onion addresses.
Understanding CVE-2021-39246
This CVE involves a vulnerability in Tor Browser that can lead to privacy compromise for visits to specific onion addresses.
What is CVE-2021-39246?
The vulnerability in Tor Browser could allow an attacker to conduct a correlation attack compromising the privacy of visits to v2 onion addresses. The exact timestamps of these visits are logged locally, potentially allowing comparison with timestamp data from the destination server.
The Impact of CVE-2021-39246
The vulnerability poses a risk of privacy breach during visits to v2 onion addresses within the Tor network.
Technical Details of CVE-2021-39246
This section delves into the technical aspects of the CVE.
Vulnerability Description
The vulnerability in Tor Browser allows a correlation attack that can jeopardize the privacy of visits to v2 onion addresses. Timestamps of these visits are stored locally, enabling comparison with potentially sensitive data.
Affected Systems and Versions
- Affected Versions: Tor Browser through 10.5.6 and 11.x to 11.0a4
- Systems: All systems using the vulnerable Tor Browser versions
Exploitation Mechanism
The attacker can leverage the vulnerability to correlate timestamp data from local logs with information collected by a destination server or rogue site within the Tor network.
Mitigation and Prevention
Protecting against and mitigating the effects of CVE-2021-39246.
Immediate Steps to Take
- Update Tor Browser to the latest version available.
- Avoid visiting v2 onion addresses until the browser is patched.
- Monitor for any unusual activity on the network.
Long-Term Security Practices
- Regularly update Tor Browser and other security software.
- Implement network segregation to minimize the impact of potential breaches.
- Educate users on the importance of privacy and safe browsing practices.
Patching and Updates
Ensure timely application of patches released by the Tor Browser project to address the vulnerability.