CVE-2016-5418 in libarchive
Summary
by MITRE
The sandboxing code in libarchive 3.2.0 and earlier mishandles hardlink archive entries of non-zero data size, which might allow remote attackers to write to arbitrary files via a crafted archive file.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2016-5418 resides within the libarchive library version 3.2.0 and earlier, representing a critical sandboxing flaw that directly impacts how the library processes archive files containing hardlink entries. This issue specifically manifests when handling hardlink archive entries that possess non-zero data size, creating a scenario where remote attackers can potentially execute arbitrary file write operations through the manipulation of crafted archive files. The fundamental problem lies in the improper handling of file system permissions and path resolution during the extraction process, which bypasses the intended security boundaries designed to prevent unauthorized system modifications.
The technical implementation of this vulnerability stems from a flaw in the sandboxing mechanism that governs how libarchive manages file system operations during archive extraction. When processing hardlink entries with data content, the library fails to properly validate the target paths against the intended extraction boundaries, allowing attackers to manipulate the extraction process to write files outside of the designated extraction directory. This mismanagement occurs because the library does not adequately verify that hardlink targets remain within the expected sandboxed environment, creating a path traversal condition that can be exploited to overwrite system files or inject malicious content into arbitrary locations on the file system. The vulnerability is particularly dangerous because it leverages legitimate archive processing functionality to achieve unauthorized file system modifications, making it difficult to detect through traditional security monitoring approaches.
The operational impact of CVE-2016-5418 extends beyond simple file system manipulation to encompass potential privilege escalation and system compromise scenarios. Attackers can exploit this vulnerability to overwrite critical system files, inject malicious code into existing programs, or create backdoor access points within the target system. The vulnerability affects systems that utilize libarchive for processing untrusted archive content, including web applications, automated build systems, and file processing services that handle user-uploaded archives. This makes it particularly dangerous in environments where archive files are processed without proper validation or sandboxing, as the attack surface becomes significantly expanded. The vulnerability's exploitation potential is further amplified by its ability to work remotely, meaning that attackers can trigger the malicious behavior without requiring local system access or physical presence.
From a cybersecurity perspective, this vulnerability aligns with several ATT&CK framework techniques including T1059 Command and Scripting Interpreter and T1566 Impair Defenses, as it enables attackers to manipulate system files and potentially bypass security controls. The flaw also corresponds to CWE-22 Improper Limitation of a Pathname to a Restricted Directory, which specifically addresses path traversal vulnerabilities in file system operations. Organizations should implement immediate mitigations including updating to libarchive version 3.2.1 or later, which contains the necessary patches to address the hardlink handling issue. Additionally, system administrators should consider implementing additional sandboxing measures, such as running archive processing operations with reduced privileges, implementing strict file system access controls, and employing content validation mechanisms to prevent the processing of untrusted archive files. The vulnerability demonstrates the critical importance of proper sandboxing implementation in security libraries and the potential consequences when such safeguards fail to properly validate file system operations during archive processing activities.