CVE-2015-8925 in libarchive
Summary
by MITRE
The readline function in archive_read_support_format_mtree.c in libarchive before 3.2.0 allows remote attackers to cause a denial of service (invalid read) via a crafted mtree file, related to newline parsing.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2015-8925 affects the libarchive library version 3.2.0 and earlier, specifically within the archive_read_support_format_mtree.c component. This issue represents a classic buffer over-read condition that occurs during the processing of mtree format archive files. The mtree format is commonly used in Unix-like systems for describing directory hierarchies and file characteristics, making it a critical component in system administration and backup operations. When a maliciously crafted mtree file is processed by libarchive, the readline function fails to properly validate newline characters during parsing, leading to an invalid memory read operation. This flaw exists in the boundary checking mechanism that handles line termination sequences, particularly when encountering malformed or specially constructed newline characters within the mtree data structure.
The technical exploitation of this vulnerability demonstrates a clear path to denial of service conditions through improper input validation. The flaw occurs in the parsing logic where the readline function attempts to read memory locations beyond the allocated buffer boundaries when processing mtree files containing crafted newline sequences. This invalid read operation typically results in segmentation faults or memory access violations that terminate the application process. The vulnerability is particularly dangerous because it can be triggered remotely through network-based archive extraction operations, allowing attackers to disrupt services without requiring local system access. The underlying cause aligns with CWE-125, which describes out-of-bounds read conditions, and represents a failure in proper input sanitization and boundary checking within the archive processing pipeline.
From an operational impact perspective, this vulnerability creates significant risks for systems that rely on libarchive for processing untrusted archive data. Network services, backup systems, and automated file processing applications that utilize libarchive are all potential targets for exploitation. The denial of service condition can be leveraged to disrupt critical infrastructure, particularly in environments where automated archive extraction occurs without proper input validation. Attackers can craft mtree files that, when processed, cause applications to crash or become unresponsive, effectively rendering the service unavailable to legitimate users. This vulnerability particularly affects systems that handle user-uploaded archives, network file transfers, or automated backup restoration processes where the source of archive data cannot be trusted.
The mitigation strategies for CVE-2015-8925 primarily focus on upgrading to libarchive version 3.2.0 or later, where the parsing logic has been corrected to properly handle newline character sequences. System administrators should prioritize patching affected systems, especially those handling untrusted archive data or serving network-based archive processing services. Additionally, implementing proper input validation and sanitization measures can provide defense-in-depth protection, though the primary fix must come from updating the vulnerable library components. Organizations should also consider implementing network segmentation and access controls to limit exposure to potentially malicious archive files, particularly in environments where automatic archive extraction occurs. The vulnerability demonstrates the importance of proper boundary checking and input validation in security-critical libraries, aligning with ATT&CK technique T1059.007 for execution through archive extraction and T1499.004 for denial of service via resource exhaustion. Regular security audits of third-party library dependencies and maintaining up-to-date software versions remain essential practices to prevent exploitation of similar vulnerabilities in the broader software ecosystem.