CVE-2015-8931 in libarchive
Summary
by MITRE
Multiple integer overflows in the (1) get_time_t_max and (2) get_time_t_min functions in archive_read_support_format_mtree.c in libarchive before 3.2.0 allow remote attackers to have unspecified impact via a crafted mtree file, which triggers undefined behavior.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2015-8931 represents a critical integer overflow flaw within the libarchive library version 3.1.5 and earlier, specifically affecting the mtree format parsing functionality. This issue resides in the archive_read_support_format_mtree.c source file where two distinct functions get_time_t_max and get_time_t_min are susceptible to integer overflow conditions. The flaw occurs when processing crafted mtree files that contain maliciously constructed time values, leading to potential exploitation by remote attackers. Integer overflows in cryptographic and archive processing libraries are particularly dangerous because they can result in memory corruption, arbitrary code execution, or denial of service conditions that compromise system integrity.
The technical implementation of this vulnerability stems from improper input validation within the time value parsing logic of mtree format handling. When the get_time_t_max and get_time_t_min functions process time values from mtree files, they fail to properly validate the range of integer values before performing arithmetic operations or assignments. This allows attackers to craft mtree files containing time values that exceed the maximum or minimum limits of the target platform's time_t data type, causing the integers to wrap around or overflow in unpredictable ways. The undefined behavior resulting from these overflows can manifest as memory corruption, stack smashing, or other low-level system instabilities that provide attack vectors for exploitation. This vulnerability directly maps to CWE-190, which describes integer overflow conditions, and specifically aligns with CWE-128, which addresses negative integer underflow scenarios.
The operational impact of CVE-2015-8931 extends beyond simple denial of service conditions to potentially enable remote code execution in vulnerable environments. Systems that utilize libarchive for processing untrusted mtree files, including web servers, file processing applications, and backup systems, become vulnerable to attacks. The unspecified impact mentioned in the CVE description reflects the difficulty in predicting exact exploitation outcomes, as integer overflows can lead to various security consequences depending on the execution environment, memory layout, and system architecture. Attackers can leverage this vulnerability by preparing specially crafted mtree files that, when processed by vulnerable applications, trigger the integer overflow conditions. This creates a persistent threat vector that can be exploited across multiple platforms and applications that depend on the affected libarchive library version.
Mitigation strategies for CVE-2015-8931 require immediate patching of affected systems to upgrade to libarchive version 3.2.0 or later, where the integer overflow conditions have been properly addressed through enhanced input validation and proper integer range checking. System administrators should conduct comprehensive vulnerability assessments to identify all applications and services that utilize the vulnerable libarchive library, particularly those handling untrusted file inputs. Additional defensive measures include implementing strict input validation for mtree files, deploying network segmentation to limit exposure, and establishing monitoring protocols to detect suspicious file processing activities. The vulnerability also highlights the importance of following secure coding practices such as those recommended in the CERT Secure Coding Standards, which emphasize proper integer overflow detection and prevention. Organizations should also consider implementing application whitelisting and sandboxing techniques to limit the potential impact of exploitation attempts, as outlined in the MITRE ATT&CK framework's techniques for privilege escalation and execution.