Vulnerabilities > CVE-2021-39246 - Information Exposure Through Log Files vulnerability in Torproject TOR Browser
Attack vector
PHYSICAL Attack complexity
LOW Privileges required
NONE Confidentiality impact
HIGH Integrity impact
HIGH Availability impact
NONE Summary
Tor Browser through 10.5.6 and 11.x through 11.0a4 allows a correlation attack that can compromise the privacy of visits to v2 onion addresses. Exact timestamps of these onion-service visits are logged locally, and an attacker might be able to compare them to timestamp data collected by the destination server (or collected by a rogue site within the Tor network).
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Fuzzing and observing application log data/errors for application mapping An attacker sends random, malformed, or otherwise unexpected messages to a target application and observes the application's log or error messages returned. Fuzzing techniques involve sending random or malformed messages to a target and monitoring the target's response. The attacker does not initially know how a target will respond to individual messages but by attempting a large number of message variants they may find a variant that trigger's desired behavior. In this attack, the purpose of the fuzzing is to observe the application's log and error messages, although fuzzing a target can also sometimes cause the target to enter an unstable state, causing a crash. By observing logs and error messages, the attacker can learn details about the configuration of the target application and might be able to cause the target to disclose sensitive information.
References
- https://sick.codes/sick-2021-111
- https://gitlab.torproject.org/tpo/core/tor/-/commit/80c404c4b79f3bcba3fc4585d4c62a62a04f3ed9
- https://www.privacyaffairs.com/cve-2021-39246-tor-vulnerability
- https://gitlab.torproject.org/tpo/core/tor/-/merge_requests/434
- https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-111.md