CVE-2015-2304 in libarchive
Summary
by MITRE
Absolute path traversal vulnerability in bsdcpio in libarchive 3.1.2 and earlier allows remote attackers to write to arbitrary files via a full pathname in an archive.
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Analysis
by VulDB Data Team • 05/01/2022
The CVE-2015-2304 vulnerability represents a critical absolute path traversal flaw within the bsdcpio utility of libarchive version 3.1.2 and earlier. This vulnerability resides in the archive extraction functionality that processes file paths contained within compressed archives, creating a potential attack vector for remote adversaries seeking to manipulate system files. The flaw specifically affects the bsdcpio component which is part of the broader libarchive library used extensively across Unix-like systems for handling various archive formats including tar, cpio, and zip files.
The technical implementation of this vulnerability stems from insufficient input validation and path sanitization within the bsdcpio utility. When processing archive files containing entries with absolute pathnames beginning with forward slashes, the utility fails to properly validate or sanitize these paths before attempting to extract files to the target system. This omission allows attackers to craft malicious archive files containing entries with absolute paths such as /etc/passwd or /usr/bin/sudo, enabling them to write files directly to system directories regardless of the intended extraction location. The vulnerability operates at the file system level where the extraction process bypasses normal path resolution mechanisms and directly writes to specified absolute locations.
The operational impact of CVE-2015-2304 is significant and multifaceted, potentially allowing for arbitrary file creation, modification, or deletion on affected systems. Remote attackers can leverage this vulnerability to place malicious files in critical system directories, potentially leading to privilege escalation, backdoor installation, or system compromise. The vulnerability is particularly dangerous in environments where users can upload or process untrusted archive files, such as web applications handling file uploads, automated build systems, or network services that decompress user-provided archives. Attackers can exploit this flaw to overwrite system binaries, modify configuration files, or inject malicious code into the target environment, effectively bypassing normal access controls and file system permissions.
This vulnerability maps directly to CWE-22 - Improper Limitation of a Pathname to a Restricted Directory, which is a well-documented weakness in software security where applications fail to properly restrict file system access based on user-provided paths. The flaw also aligns with ATT&CK technique T1059.007 - Command and Scripting Interpreter: PowerShell, as attackers may use the ability to write arbitrary files to establish persistence mechanisms or deploy additional malicious payloads. The vulnerability demonstrates a classic case of insufficient input validation in file system operations, where the security boundary between user-controlled data and system resources is improperly enforced. Organizations should consider implementing comprehensive mitigation strategies including immediate patching of affected libarchive versions, implementing strict file path validation in applications that handle archive processing, and deploying network segmentation to limit exposure of systems that process untrusted archive files.
The remediation approach for CVE-2015-2304 requires immediate updating of libarchive to version 3.1.3 or later, where the vulnerability has been addressed through proper path validation and sanitization. System administrators should also implement defensive measures such as restricting write permissions for critical system directories, implementing mandatory access controls, and monitoring archive processing activities for suspicious path patterns. Additionally, organizations should conduct security assessments to identify systems running vulnerable versions of libarchive and ensure that all archive processing components properly validate and sanitize file paths before execution. The fix implemented in later versions typically involves adding checks to prevent extraction of files with absolute paths or implementing proper path normalization that strips out dangerous path components before file system operations occur.