CVE-2015-8927 in libarchive
Summary
by MITRE
The trad_enc_decrypt_update function in archive_read_support_format_zip.c in libarchive before 3.2.0 allows remote attackers to cause a denial of service (out-of-bounds heap read and crash) via a crafted zip file, related to reading the password.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2015-8927 represents a critical heap-based buffer over-read condition within the libarchive library's ZIP file processing functionality. This flaw exists in the trad_enc_decrypt_update function located within the archive_read_support_format_zip.c source file, affecting all versions prior to 3.2.0. The vulnerability manifests when the library processes specially crafted ZIP archives that contain encrypted entries with malformed password data, creating a scenario where memory access occurs beyond the bounds of allocated heap buffers.
The technical nature of this vulnerability stems from inadequate input validation and boundary checking within the decompression and decryption routines of the ZIP format handler. When a malicious ZIP file contains crafted password information, the trad_enc_decrypt_update function fails to properly validate the length and structure of the encrypted data before attempting to process it. This leads to a heap-based buffer over-read condition where the application attempts to read memory locations that are outside the legitimate bounds of the allocated buffer, resulting in unpredictable behavior including application crashes and potential information disclosure.
From an operational perspective, this vulnerability presents a significant denial of service risk to any system or application that relies on libarchive for processing ZIP files. Attackers can exploit this weakness by crafting malicious ZIP archives that trigger the vulnerable code path during decompression operations, causing the target application to crash or become unresponsive. The impact extends beyond simple service disruption as the vulnerability could potentially be leveraged in more sophisticated attacks if the heap corruption leads to information leakage or if the crash occurs in a context where the application's memory state could be manipulated. The vulnerability affects a wide range of applications including web servers, file processing utilities, and content management systems that utilize libarchive for archive handling.
The flaw aligns with CWE-125, which describes out-of-bounds read vulnerabilities, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for command and scripting interpreter execution, though the primary impact remains denial of service rather than arbitrary code execution. This vulnerability represents a classic example of how improper input validation in cryptographic operations can lead to system instability and service disruption. The remediation strategy involves upgrading to libarchive version 3.2.0 or later, where the buffer over-read condition has been addressed through improved input validation and boundary checking mechanisms. Organizations should also implement proper input sanitization measures and consider deploying intrusion detection systems that can identify and block malicious ZIP file content that may trigger this vulnerability. Additionally, network segmentation and application whitelisting strategies can help limit the potential impact of exploitation attempts targeting systems that process untrusted archive files.