CVE-2011-2902 in Xpdf
Summary
by MITRE
zxpdf in xpdf before 3.02-19 as packaged in Debian unstable and 3.02-12+squeeze1 as packaged in Debian squeeze deletes temporary files insecurely, which allows remote attackers to delete arbitrary files via a crafted .pdf.gz file name.
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Analysis
by VulDB Data Team • 06/17/2020
The vulnerability identified as CVE-2011-2902 affects zxpdf, a component of the xpdf suite, specifically targeting versions packaged in Debian unstable and squeeze distributions. This flaw represents a critical insecure temporary file handling issue that can be exploited remotely to execute arbitrary file deletion operations on affected systems. The vulnerability stems from improper management of temporary files during PDF processing, creating a pathway for malicious actors to manipulate the file system through crafted input.
The technical implementation of this vulnerability involves the insecure deletion of temporary files created during PDF decompression and processing operations. When zxpdf encounters a .pdf.gz file, it creates temporary files in a predictable location within the file system. The insecure handling occurs because the application does not properly validate or sanitize the file names passed to the decompression routine, allowing attackers to craft malicious file names that can manipulate the temporary file deletion process. This behavior aligns with CWE-377, which addresses insecure temporary file handling, and CWE-22, covering improper limitation of a pathname to a restricted directory.
The operational impact of this vulnerability extends beyond simple file deletion, as it can be leveraged to perform more sophisticated attacks within compromised systems. Remote attackers can exploit this weakness to delete critical system files, configuration data, or user documents, potentially leading to system instability, data loss, or service disruption. The vulnerability's remote exploitability means that attackers do not need local access to the system, making it particularly dangerous in multi-user environments or web-facing applications where PDF processing is enabled. This weakness can be categorized under ATT&CK technique T1059.007 for command and scripting interpreter and T1485 for data destruction.
Mitigation strategies for this vulnerability require immediate patching of affected systems with updated xpdf versions that properly handle temporary files. System administrators should ensure that all Debian systems running affected versions of zxpdf are updated to patched releases, specifically versions 3.02-19 for unstable and 3.02-12+squeeze1 for squeeze. Additional protective measures include implementing proper file system permissions, restricting PDF processing capabilities in web applications, and monitoring for suspicious file operations. The vulnerability highlights the importance of secure coding practices in file system operations and demonstrates how seemingly minor implementation flaws can result in significant security implications. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of such vulnerabilities in their environments.