CVE-2011-0016 in Tor
Summary
by MITRE
Tor before 0.2.1.29 and 0.2.2.x before 0.2.2.21-alpha does not properly manage key data in memory, which might allow local users to obtain sensitive information by leveraging the ability to read memory that was previously used by a different process.
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Analysis
by VulDB Data Team • 08/03/2024
The vulnerability identified as CVE-2011-0016 represents a critical memory management flaw within the Tor anonymization network software that affected versions prior to 0.2.1.29 and 0.2.2.x versions before 0.2.2.21-alpha. This issue stems from improper handling of cryptographic key material and sensitive data within the application's memory space, creating potential information disclosure risks for local attackers. The flaw specifically manifests when Tor processes terminate or when memory is reallocated, leaving remnants of sensitive cryptographic data accessible to unauthorized local users who can read previously utilized memory segments. This vulnerability directly relates to CWE-200, which encompasses information exposure through improper handling of sensitive data, and aligns with ATT&CK technique T1005 for data from local system.
The technical implementation of this vulnerability exploits the fundamental memory management practices within Tor's cryptographic operations. When Tor processes handle cryptographic keys, session data, and other sensitive information, they store this data in memory locations that are not properly sanitized or overwritten before being made available for reuse by other processes. Attackers can leverage memory reading capabilities to access these residual data fragments, potentially recovering cryptographic keys, session identifiers, or other confidential information that was previously processed by Tor. The vulnerability is particularly concerning because Tor's primary function involves handling sensitive communications and maintaining user anonymity, making any information disclosure potentially catastrophic for user privacy and security.
The operational impact of CVE-2011-0016 extends beyond simple information disclosure, as it undermines the core security guarantees that Tor provides to its users. Local attackers with memory reading privileges can potentially reconstruct cryptographic session data, which may lead to session hijacking, decryption of communications, or other attacks that compromise the anonymity properties that Tor is designed to protect. This vulnerability affects the integrity of the Tor network's security model by creating persistent information leakage channels that can be exploited across multiple Tor processes and sessions. The risk is particularly elevated in environments where multiple users or processes share system resources, as attackers can potentially cross-compile information across different Tor instances that have been running sequentially.
Mitigation strategies for this vulnerability require immediate patching of affected Tor versions to the secure releases that properly implement memory sanitization and key management practices. System administrators should ensure all Tor installations are updated to versions 0.2.1.29 or later for the 0.2.1.x series, and 0.2.2.21-alpha or later for the 0.2.2.x series. Additionally, organizations should implement proper memory management practices including secure memory deallocation, zeroing out sensitive data before memory reuse, and employing techniques such as memory locking to prevent data from being swapped to disk. The vulnerability highlights the importance of following secure coding practices for cryptographic applications and demonstrates the necessity of thorough memory management in security-sensitive software. Security teams should also consider implementing monitoring for unauthorized memory access patterns and establish proper system hardening measures to reduce the attack surface available to local adversaries.