CVE-2004-1170 in Linux
Summary
by MITRE
a2ps 4.13 allows remote attackers to execute arbitrary commands via shell metacharacters in the filename.
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Analysis
by VulDB Data Team • 12/07/2024
The vulnerability identified as CVE-2004-1170 affects a2ps version 4.13, a command-line utility designed to convert text files into PostScript format for printing. This tool is commonly used in Unix-like operating systems for processing document formatting tasks and has been widely distributed as part of various software packages and system utilities. The flaw manifests in how the application handles filename parameters, creating a critical security risk that can be exploited by remote attackers without authentication.
The technical implementation of this vulnerability stems from inadequate input validation within the a2ps application's filename processing logic. When users provide filenames as command-line arguments, the software fails to properly sanitize or escape special shell metacharacters such as semicolons, ampersands, pipes, and backticks. These characters, when processed directly without proper sanitization, can be interpreted by the underlying shell as command delimiters or execution operators, allowing attackers to inject malicious commands that execute with the privileges of the a2ps process. This represents a classic command injection vulnerability that operates at the application layer and can be exploited through various attack vectors including web interfaces, automated scripts, or direct network-based exploitation.
The operational impact of this vulnerability extends beyond simple command execution, as it provides attackers with significant system compromise capabilities. Remote attackers can leverage this flaw to execute arbitrary code on vulnerable systems, potentially leading to complete system takeover, data exfiltration, or persistence mechanisms. The vulnerability affects systems where a2ps is installed and accessible to untrusted users, making it particularly dangerous in multi-user environments or web applications that utilize this utility for document processing. The attack surface is broad since a2ps is often used in automated workflows, print servers, and web applications that process user-supplied filenames, amplifying the potential damage. According to CWE standards, this vulnerability maps to CWE-78, which specifically addresses improper neutralization of special elements used in OS commands, and aligns with ATT&CK technique T1059.001 for command and script interpreters. The vulnerability also relates to broader concepts of privilege escalation and remote code execution that are fundamental to cybersecurity risk management.
Mitigation strategies for CVE-2004-1170 require immediate action to address the root cause through proper input sanitization and command execution practices. System administrators should upgrade to patched versions of a2ps, as version 4.14 and later contain proper input validation mechanisms that prevent shell metacharacter interpretation. In environments where upgrading is not immediately possible, administrators can implement strict input validation at the application level, ensuring that all filename parameters are properly escaped or sanitized before being passed to shell commands. Additionally, implementing proper privilege separation and sandboxing techniques can limit the impact of successful exploitation attempts. Network-level mitigations such as firewall rules that restrict access to a2ps functionality and input filtering at proxy or gateway levels can provide additional defense-in-depth measures. Organizations should also conduct comprehensive vulnerability assessments to identify all instances of a2ps and similar utilities that may be vulnerable to command injection attacks, ensuring that all systems are properly secured against this class of vulnerability. The remediation process should include monitoring for exploitation attempts and implementing proper logging mechanisms to track command execution patterns that may indicate successful exploitation of this vulnerability.