CVE-2008-5397 in Tor
Summary
by MITRE
Tor before 0.2.0.32 does not properly process the (1) User and (2) Group configuration options, which might allow local users to gain privileges by leveraging unintended supplementary group memberships of the Tor process.
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Analysis
by VulDB Data Team • 09/01/2019
The vulnerability described in CVE-2008-5397 affects the Tor anonymization network software version 0.2.0.31 and earlier, presenting a significant privilege escalation risk for local attackers. This flaw resides in the Tor process's handling of user and group configuration parameters, specifically within the software's privilege management mechanisms. The issue stems from how Tor processes the User and Group configuration options, which are designed to control the operating system user and group under which the Tor daemon runs. When these configuration parameters are improperly processed, the Tor process may inherit unintended supplementary group memberships that were not explicitly intended by the system administrator.
The technical nature of this vulnerability allows local attackers to exploit the improper handling of supplementary group memberships to escalate their privileges on the system. According to CWE-276, this represents a classic improper privilege management issue where the software fails to properly enforce access controls. The flaw occurs because the Tor software does not correctly validate or sanitize the group membership information when switching user contexts, potentially allowing the process to retain access to resources that should be restricted to specific user groups. This misconfiguration creates a pathway for attackers to leverage the Tor process's elevated privileges to access restricted system resources or perform actions that would normally be prohibited for regular users.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can enable attackers to compromise the integrity and confidentiality of the Tor network infrastructure. When local users can exploit this vulnerability, they may gain access to sensitive network communications, potentially undermining the anonymity guarantees that Tor provides. This weakness also creates opportunities for attackers to manipulate the Tor process itself, potentially leading to more severe consequences such as data exfiltration or the compromise of other network services running on the same system. The vulnerability affects systems where Tor is configured to run with specific user and group permissions, making it particularly dangerous in environments where multiple users share the same system or where Tor is deployed in security-sensitive contexts.
Mitigation strategies for this vulnerability require immediate patching to Tor version 0.2.0.32 or later, which contains the necessary fixes for proper group membership handling. System administrators should also implement strict configuration management practices, ensuring that Tor processes run with the minimal necessary privileges and that supplementary group memberships are explicitly controlled. The fix addresses the underlying issue by properly validating and sanitizing the User and Group configuration options before the Tor process attempts to switch contexts. Organizations should also consider implementing additional security controls such as mandatory access controls, privilege separation mechanisms, and regular security auditing of system configurations. According to ATT&CK framework, this vulnerability maps to privilege escalation techniques where attackers leverage improper privilege management to gain elevated system access, making it a critical concern for security operations centers that monitor for such attack patterns.