CVE-2015-8107 in a2ps
Summary
by MITRE
Format string vulnerability in GNU a2ps 4.14 allows remote attackers to execute arbitrary code.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/30/2020
The CVE-2015-8107 vulnerability represents a critical format string vulnerability within GNU a2ps version 4.14, a widely used command-line utility for converting text files into printable PostScript documents. This vulnerability exists in the program's handling of user-supplied input during string formatting operations, creating a potential pathway for remote code execution attacks. The flaw specifically manifests when the application processes format specifiers in user-provided data without proper validation or sanitization, allowing malicious actors to manipulate memory layout and execute arbitrary code on systems running the vulnerable software.
This vulnerability falls under the CWE-134 category of "Use of Externally-Controlled Format String," which is classified as a serious weakness in software security practices. The attack vector leverages the improper use of functions such as printf, sprintf, or fprintf where format string arguments are derived from external sources rather than being hardcoded. In the context of GNU a2ps, this occurs when the application accepts user input that contains format specifiers, which are then processed by these vulnerable functions. The vulnerability enables attackers to exploit the format string mechanism to read from or write to arbitrary memory locations, potentially leading to complete system compromise.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with the ability to manipulate program flow and potentially gain elevated privileges. When exploited, the vulnerability allows remote attackers to inject malicious code that can execute with the privileges of the a2ps process, which typically runs with the permissions of the user invoking the utility. This presents a significant risk in environments where a2ps is used in automated processes or web applications, where attackers could leverage the vulnerability to establish persistent backdoors or escalate their privileges within the system. The remote nature of the attack means that exploitation can occur without requiring local access to the target system, making it particularly dangerous in networked environments.
Mitigation strategies for CVE-2015-8107 should prioritize immediate patching of the affected GNU a2ps version 4.14 to the latest available release that contains the fix for this vulnerability. System administrators should also implement network segmentation and access controls to limit exposure of systems running vulnerable versions of a2ps. Additional protective measures include input validation and sanitization of all user-supplied data, implementing proper format string handling practices that prevent external input from being used as format specifiers, and monitoring for suspicious usage patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of following secure coding practices and adheres to ATT&CK technique T1059.007 for command and script injection, highlighting the need for robust input validation and output encoding mechanisms in all software applications. Organizations should also consider implementing intrusion detection systems to monitor for exploitation attempts and maintain up-to-date vulnerability management processes to prevent similar issues from occurring in other software components.