CVE-2004-2215 in rxvt-unicode
Summary
by MITRE
rxvt-unicode 3.4 and 3.5 does not properly close file descriptors which allows local users to access the terminals of other users and possibly gain privileges.
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Analysis
by VulDB Data Team • 06/25/2018
The vulnerability identified as CVE-2004-2215 affects rxvt-unicode terminal emulators version 3.4 and 3.5, representing a critical security flaw in Unix-like operating systems. This issue stems from improper handling of file descriptor closure within the terminal emulator's codebase, creating a persistent security weakness that can be exploited by local attackers. The vulnerability specifically targets the terminal multiplexing functionality that allows multiple users to share terminal sessions while maintaining distinct security boundaries. When the terminal emulator fails to properly close file descriptors, it creates a window of opportunity for malicious users to access other users' terminal sessions through the improperly managed file handles.
The technical flaw manifests in the terminal emulator's process management and resource cleanup mechanisms, where file descriptors associated with terminal sessions remain open even after the session should have terminated. This improper resource management creates a scenario where file descriptors from one user's session can be accessed by another user, effectively allowing information disclosure and potential privilege escalation. The vulnerability operates at the system call level where file descriptor inheritance and process isolation should prevent cross-session access. According to CWE standards, this corresponds to CWE-242, which describes the weakness of using potentially insecure functions that can lead to resource management issues. The flaw essentially violates the principle of least privilege by allowing unauthorized access to terminal resources that should remain isolated between users.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable privilege escalation attacks. Local users who exploit this flaw can gain access to other users' terminal sessions, which may contain sensitive data, authentication tokens, or system credentials. This access could allow attackers to monitor other users' activities, inject malicious commands, or even escalate their privileges if they can manipulate the terminal session to execute elevated commands. The vulnerability affects multi-user environments where multiple users share the same system and rely on terminal sessions for their work. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and credential access, specifically leveraging process injection and resource hijacking methods to gain unauthorized access to system resources. The impact is particularly severe in environments where terminal sessions contain sensitive information or administrative access.
Mitigation strategies for CVE-2004-2215 involve immediate patching of the affected rxvt-unicode versions, with the release of version 3.6 addressing the file descriptor management issue. System administrators should implement comprehensive monitoring for unauthorized terminal access attempts and establish proper file descriptor cleanup procedures. The vulnerability highlights the importance of proper resource management in terminal emulators and similar system tools, emphasizing the need for robust process isolation mechanisms. Organizations should also consider implementing additional security controls such as terminal session auditing, access logging, and privilege separation measures to prevent exploitation of similar resource management flaws. Regular security assessments of terminal emulators and other system tools should include thorough testing of file descriptor handling and process isolation mechanisms to identify potential vulnerabilities before they can be exploited by malicious actors.