CVE-2008-4960 in impose+
Summary
by MITRE
impose in impose+ 0.2 allows local users to overwrite arbitrary files via a symlink attack on (1) /tmp/*-tmp.ps and (2) /tmp/bboxx-* temporary files.
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Analysis
by VulDB Data Team • 11/27/2017
The vulnerability identified as CVE-2008-4960 affects the impose+ software version 0.2, presenting a significant security risk through a symlink attack mechanism that enables local users to overwrite arbitrary files on the system. This flaw resides in the improper handling of temporary files during the processing of PostScript documents, specifically within the temporary file creation and management routines. The issue manifests when the impose+ utility creates temporary files in the /tmp directory without adequate security measures to prevent symbolic link manipulation by unauthorized users.
The technical implementation of this vulnerability stems from the software's failure to validate the existence and ownership of temporary file paths before writing to them. When impose+ processes documents, it generates temporary files with predictable naming patterns such as /tmp/-tmp.ps and /tmp/bboxx- which are susceptible to symlink attacks. An attacker with local access can create symbolic links with these exact names in the /tmp directory before the legitimate process runs, causing the impose+ utility to write sensitive data to locations controlled by the attacker rather than the intended temporary file locations. This represents a classic race condition vulnerability where the timing of file creation and access allows for malicious interference.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities, as it can potentially lead to privilege escalation and system compromise. Local attackers can leverage this weakness to replace critical system files, inject malicious code into temporary files that will be processed by other applications, or manipulate the output of the impose+ utility to redirect processing to attacker-controlled locations. The vulnerability affects any system where impose+ is installed and executed with elevated privileges, making it particularly dangerous in multi-user environments or systems where users have local login access. The attack vector requires local system access but does not require network connectivity or special privileges beyond what a regular user might possess.
Mitigation strategies for CVE-2008-4960 should focus on implementing proper temporary file handling mechanisms that prevent symlink attacks. The most effective approach involves using secure temporary file creation methods that ensure file integrity and prevent symbolic link manipulation, such as creating temporary files with random names and using appropriate file permissions. System administrators should also consider implementing restrictive file permissions on the /tmp directory and applying the principle of least privilege to limit the execution scope of the impose+ utility. Additionally, the software should be updated to versions that properly implement secure file handling practices, including the use of atomic file creation techniques that prevent race conditions. This vulnerability aligns with CWE-377 and CWE-378 categories related to insecure temporary file handling and improper temporary file permissions, and it maps to ATT&CK technique T1059 for execution through command-line interfaces and T1548 for privilege escalation through file permissions. Organizations should conduct regular security audits to identify similar vulnerabilities in other software components and implement comprehensive temporary file management policies across their systems.