CVE-2008-3863 in Enscript
Summary
by MITRE
Stack-based buffer overflow in the read_special_escape function in src/psgen.c in GNU Enscript 1.6.1 and 1.6.4 beta, when the -e (aka special escapes processing) option is enabled, allows user-assisted remote attackers to execute arbitrary code via a crafted ASCII file, related to the setfilename command.
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Analysis
by VulDB Data Team • 08/20/2019
The vulnerability identified as CVE-2008-3863 represents a critical stack-based buffer overflow within GNU Enscript version 1.6.1 and 1.6.4 beta, specifically within the read_special_escape function located in src/psgen.c. This flaw manifests when the application processes files with the -e command line option enabled, which activates special escapes processing. The vulnerability stems from inadequate input validation and bounds checking in the handling of ASCII files that contain crafted payloads designed to exploit the buffer overflow condition. The affected software processes these special escape sequences without sufficient safeguards, creating a scenario where malicious input can overwrite adjacent memory locations on the stack.
The technical exploitation of this vulnerability occurs through a carefully constructed ASCII file that triggers the buffer overflow when processed by GNU Enscript with special escapes enabled. When the read_special_escape function encounters such malicious input, it fails to properly validate the length of data being read into a fixed-size buffer, allowing an attacker to overflow the stack space allocated for this operation. This overflow can overwrite return addresses, function pointers, and other critical stack data, enabling an attacker to redirect program execution flow. The vulnerability is classified as a stack-based buffer overflow, which directly maps to CWE-121, and represents a classic example of unsafe string handling that has been documented in numerous security advisories and penetration testing reports. The attack vector is particularly concerning because it requires only a user-assisted remote scenario, meaning an attacker can craft a malicious file that, when processed by an unsuspecting user running GNU Enscript with the affected option, will trigger the exploit.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with the capability to gain arbitrary code execution privileges on systems running vulnerable versions of GNU Enscript. This type of privilege escalation can lead to complete system compromise, data exfiltration, or the establishment of persistent backdoors within network environments. The vulnerability affects systems where GNU Enscript is used for document processing, particularly in server environments or applications that process untrusted user input through the enscript command. From an ATT&CK framework perspective, this vulnerability maps to techniques involving code injection and privilege escalation, specifically leveraging the T1059.007 command and script interpreter sub-technique for executing malicious code through command line interfaces. Organizations using GNU Enscript in production environments, especially those processing user-uploaded documents or files from untrusted sources, face significant risk from this vulnerability.
Mitigation strategies for CVE-2008-3863 should prioritize immediate patching of affected systems with updated versions of GNU Enscript that contain proper bounds checking and input validation mechanisms. System administrators should disable the -e option when processing untrusted files or implement strict input sanitization protocols before file processing. Network segmentation and access controls can help limit the potential impact of exploitation, while monitoring systems should be configured to detect unusual command execution patterns that might indicate exploitation attempts. The vulnerability also highlights the importance of proper software security practices including input validation, bounds checking, and regular security updates, aligning with industry standards such as those outlined in the OWASP Top Ten and NIST cybersecurity guidelines. Additionally, organizations should consider implementing application whitelisting policies to restrict execution of vulnerable versions of GNU Enscript and ensure that all software components are regularly assessed for similar security flaws through vulnerability scanning and penetration testing procedures.