CVE-2016-4300 in libarchive
Summary
by MITRE
Integer overflow in the read_SubStreamsInfo function in archive_read_support_format_7zip.c in libarchive before 3.2.1 allows remote attackers to execute arbitrary code via a 7zip file with a large number of substreams, which triggers a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2016-4300 represents a critical integer overflow flaw within the libarchive library's 7zip format handling component. This issue affects versions prior to 3.2.1 and stems from improper input validation in the read_SubStreamsInfo function located in archive_read_support_format_7zip.c. The flaw manifests when processing 7zip archives containing an excessive number of substreams, creating a condition where integer arithmetic operations exceed their maximum representable values. This particular vulnerability maps to CWE-190, which specifically addresses integer overflow conditions that can lead to buffer overflows and arbitrary code execution.
The technical implementation of this vulnerability involves the manipulation of the 7zip file format's internal structure during the parsing of substream information. When the read_SubStreamsInfo function processes a maliciously crafted 7zip archive, it fails to properly validate the number of substreams specified in the archive metadata. This validation failure allows an attacker to craft a file where the substream count parameter, when processed through integer arithmetic operations, results in an overflow condition. The overflow subsequently leads to a heap-based buffer overflow during memory allocation operations, as the system attempts to allocate memory based on the corrupted integer value.
From an operational perspective, this vulnerability presents a significant risk to systems that process untrusted 7zip archives, particularly those that serve as file processing services or handle user-uploaded content. Attackers can exploit this flaw by preparing a specially crafted 7zip archive containing an excessive number of substreams, which when processed by vulnerable applications, results in arbitrary code execution. The impact extends across various systems including web servers, file processing applications, and content management systems that utilize libarchive for archive handling. This vulnerability aligns with ATT&CK technique T1059.007, which covers execution through script interpreters, as the exploitation could occur through automated file processing systems.
The exploitation of CVE-2016-4300 typically requires a remote attacker to deliver a malicious 7zip file to a target system running vulnerable software. The attack vector is particularly dangerous because it can be executed without requiring user interaction, making it suitable for automated exploitation campaigns. The vulnerability affects not only direct applications using libarchive but also indirect consumers such as web applications, email servers, and content delivery networks that process compressed archives. Organizations should implement immediate mitigations including updating to libarchive version 3.2.1 or later, implementing proper input validation for archive processing, and deploying network-based intrusion detection systems to monitor for suspicious archive processing activities. Additionally, security teams should consider implementing sandboxed environments for archive processing and regular vulnerability assessments to identify other potential integer overflow conditions in similar libraries and applications.