CVE-2015-8918 in libarchive
Summary
by MITRE
The archive_string_append function in archive_string.c in libarchive before 3.2.0 allows remote attackers to cause a denial of service (crash) via a crafted cab files, related to "overlapping memcpy."
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2015-8918 affects the libarchive library version 3.1.5 and earlier, specifically within the archive_string_append function located in archive_string.c. This flaw represents a critical security issue that enables remote attackers to execute a denial of service attack by crafting malicious cab files. The vulnerability stems from improper handling of memory operations during string appending processes, creating a scenario where overlapping memory regions are processed incorrectly. The technical implementation involves the function's failure to properly validate memory copy operations when processing archive data structures, particularly those found in cab file formats. This improper memory management creates a condition where the system crashes when attempting to process specially constructed archive files that contain overlapping memory references.
The operational impact of this vulnerability extends across numerous applications and systems that rely on libarchive for archive processing, including web servers, file management systems, and content delivery networks that handle user-uploaded archive files. Attackers can exploit this weakness by uploading or transmitting crafted cab files that trigger the memory corruption during the archive_string_append function execution. The crash occurs because the overlapping memcpy operation attempts to copy memory regions where the source and destination overlap, leading to undefined behavior and system instability. This vulnerability directly relates to CWE-121, which addresses stack-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read scenarios. The attack vector operates through network-based delivery of malicious archive files, making it particularly dangerous for web applications that accept user uploads or process external archive data without proper validation.
From an attack framework perspective, this vulnerability aligns with ATT&CK technique T1203, which involves exploiting software vulnerabilities to gain access to systems or cause denial of service conditions. The exploit requires minimal privileges and can be executed remotely, making it attractive to threat actors seeking to disrupt services or cause system instability. The vulnerability demonstrates poor input validation and memory management practices within the libarchive library's string handling components, creating a persistent risk for any system that processes untrusted archive data. Organizations using affected versions of libarchive should prioritize immediate remediation through version upgrades to 3.2.0 or later, as this release includes proper memory handling and validation mechanisms that prevent the overlapping memcpy operations from causing system crashes. Additionally, implementing proper input sanitization and archive file validation at the application level can provide additional defense-in-depth measures against exploitation attempts. The vulnerability highlights the importance of proper memory management practices and the necessity of thorough testing for edge cases in archive processing libraries that handle complex file formats with overlapping data structures.