CVE-2006-4124 in LessTif
Summary
by MITRE
The libXm library in LessTif 0.95.0 and earlier allows local users to gain privileges via the DEBUG_FILE environment variable, which is used to create world-writable files when libXm is run from a setuid program.
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Analysis
by VulDB Data Team • 07/13/2024
The vulnerability identified as CVE-2006-4124 resides within the LessTif library version 0.95.0 and earlier, specifically affecting the libXm component that handles graphical user interface elements. This issue represents a critical privilege escalation flaw that enables local attackers to elevate their system privileges through manipulation of environment variables. The vulnerability occurs when the libXm library is executed within a setuid context, creating a dangerous condition where user-controlled input directly influences file creation operations with elevated permissions.
The technical flaw manifests through the DEBUG_FILE environment variable implementation within the libXm library. When a setuid program utilizing this library executes, the library processes the DEBUG_FILE variable to determine where to write debug information. However, the implementation fails to properly validate or sanitize this environment variable, allowing attackers to specify arbitrary file paths that result in the creation of world-writable files. This behavior directly violates security principles by enabling unauthorized modification of system resources that should remain protected. The vulnerability is categorized under CWE-73 as "External Control of File Name or Path" and aligns with CWE-276 as "Improper File Permissions" in the context of creating files with excessive access rights.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and data integrity violations. Local attackers can exploit this flaw to create malicious files with world-writable permissions in locations accessible to other users, potentially enabling them to inject code or modify system resources. The implications are particularly severe when the vulnerable library is used within setuid programs, as these applications typically run with elevated privileges and can affect system-wide security controls. Attackers can leverage this vulnerability to establish persistent access mechanisms or manipulate system configurations through the creation of malicious debug files that may be processed by other system components. This vulnerability directly maps to techniques described in the MITRE ATT&CK framework under T1068 as "Local Privilege Escalation" and T1546 as "Event Triggered Execution" when considering the potential for creating malicious files that could be executed by other processes.
Mitigation strategies for CVE-2006-4124 require immediate action to address the root cause through software updates and environmental controls. The primary remediation involves upgrading to LessTif versions 0.95.1 and later, which contain patches specifically addressing the improper handling of the DEBUG_FILE environment variable. System administrators should also implement environment variable sanitization policies that prevent the propagation of potentially dangerous variables to setuid programs, particularly those related to file creation and debugging operations. Additional controls include monitoring for unauthorized modifications to system files and implementing strict file permission controls that prevent the creation of world-writable files in critical system directories. Organizations should conduct comprehensive vulnerability assessments to identify all instances of the vulnerable library and ensure proper patch management procedures are in place to prevent similar issues from arising in other system components. The vulnerability serves as a reminder of the critical importance of secure coding practices in system libraries and the need for proper input validation when handling environment variables in privileged contexts.