CVE-2015-8917 in libarchive
Summary
by MITRE
bsdtar in libarchive before 3.2.0 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via an invalid character in the name of a cab file.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2015-8917 affects bsdtar, a component within the libarchive library ecosystem, specifically versions prior to 3.2.0. This flaw manifests as a denial of service condition that can be triggered remotely by manipulating the naming conventions within cab files. The libarchive library serves as a comprehensive archive manipulation framework that supports numerous formats including tar, zip, and cab among others. When processing cab files, bsdtar fails to properly validate character sequences in file names, creating a path for exploitation that leads to system instability.
The technical root cause of this vulnerability stems from inadequate input validation within the cab file parsing logic. When bsdtar encounters a cab file containing invalid characters in its file names, the parsing routine attempts to dereference a NULL pointer, resulting in an immediate crash of the application. This NULL pointer dereference represents a classic software flaw that falls under the CWE-476 category of NULL Pointer Dereference. The vulnerability specifically impacts the handling of character encoding within cab file metadata, where malformed character sequences bypass normal validation checks and propagate through the parsing pipeline to trigger the crash condition.
The operational impact of this vulnerability extends beyond simple service disruption to encompass broader security implications. Remote attackers can leverage this flaw to systematically crash systems that process cab files, potentially leading to availability issues for critical services. The attack vector requires only the ability to deliver a malicious cab file to a target system, making it particularly dangerous in environments where automated archive processing occurs. Systems that rely on libarchive for handling untrusted archive content become vulnerable to this attack, including web servers, file processing services, and automated build systems. The vulnerability can be exploited in both direct attack scenarios and as part of broader exploitation chains where denial of service serves as a precursor to more sophisticated attacks.
Mitigation strategies for CVE-2015-8917 primarily focus on immediate version updates to libarchive 3.2.0 or later, which contain the necessary patches to address the NULL pointer dereference issue. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly. Additionally, deploying network-based intrusion detection systems that can identify suspicious cab file traffic may provide early warning capabilities. Input validation should be enhanced at multiple levels including application firewalls, content filtering systems, and automated processing pipelines to prevent malformed cab files from reaching vulnerable components. Security teams should also consider implementing sandboxed processing environments for archive files to limit the impact of potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and represents a common pattern of resource exhaustion through improper input handling that can be addressed through proper defensive measures.