CVE-2016-2335 in 7-zip
Summary
by MITRE
The CInArchive::ReadFileItem method in Archive/Udf/UdfIn.cpp in 7zip 9.20 and 15.05 beta and p7zip allows remote attackers to cause a denial of service (out-of-bounds read) or execute arbitrary code via the PartitionRef field in the Long Allocation Descriptor in a UDF file.
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Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2016-2335 represents a critical security flaw within the 7zip archiving software suite, specifically affecting versions 9.20 and 15.05 beta along with p7zip implementations. This issue resides in the CInArchive::ReadFileItem method located within the Archive/Udf/UdfIn.cpp file, which processes Universal Disk Format (UDF) files during archive extraction operations. The vulnerability manifests when processing malformed UDF files containing specially crafted PartitionRef fields within Long Allocation Descriptors, creating a dangerous condition that can be exploited by remote attackers to either disrupt system availability or gain unauthorized code execution privileges.
The technical root cause of this vulnerability stems from insufficient input validation and boundary checking within the UDF parsing logic. When the 7zip application encounters a UDF file with an improperly formatted PartitionRef field, the CInArchive::ReadFileItem method fails to properly validate the field's boundaries before attempting to read data from memory locations that may be outside the intended buffer limits. This out-of-bounds read condition can result in unpredictable behavior including application crashes, memory corruption, or potentially allow attackers to execute arbitrary code by manipulating the memory layout through carefully crafted input data. The vulnerability specifically targets the Long Allocation Descriptor structure within UDF files, where the PartitionRef field contains a value that exceeds the expected bounds, causing the application to read beyond allocated memory regions.
From an operational impact perspective, this vulnerability poses significant risks to systems utilizing 7zip or p7zip for archive processing, particularly in environments where untrusted archive files are processed automatically or when users have the ability to upload or receive archive files from external sources. The potential for remote code execution makes this vulnerability particularly dangerous in web applications, email systems, or automated file processing environments where users might unknowingly trigger the vulnerable code path. The denial of service aspect alone can render systems unusable by causing repeated application crashes when processing maliciously crafted UDF archives, potentially leading to service disruption and resource exhaustion attacks.
The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions in software implementations, and represents a classic example of memory safety issues that have plagued many archive processing libraries. From an attacker's perspective, this flaw maps to several ATT&CK techniques including T1059 for command and scripting interpreter usage, T1203 for Exploitation for Client Execution, and T1499 for Endpoint Denial of Service, as it enables both code execution and system availability compromise. The attack surface is particularly broad since UDF files are commonly used in optical media, digital cameras, and various multimedia applications, making the vulnerability exploitable across multiple attack vectors.
Effective mitigation strategies for this vulnerability include immediate patching of 7zip and p7zip installations to versions that contain proper boundary checking and input validation for UDF file processing. Organizations should implement strict file validation policies that prevent automatic processing of untrusted archive files, particularly those with UDF extensions or content. Network-level controls such as sandboxing archive processing operations, implementing file type whitelisting, and deploying intrusion detection systems that monitor for suspicious archive file patterns can provide additional defense layers. System administrators should also consider disabling UDF support entirely in environments where it is not required, and implement regular security scanning of archive files using multiple antivirus and security tools to detect potentially malicious content before processing. The vulnerability demonstrates the critical importance of proper input validation in archive processing libraries and serves as a reminder of the need for comprehensive security testing in file format parsers.