CVE-2023-45853 in zlib
Summary
by MITRE • 10/25/2023
MiniZip in zlib through 1.3 has an integer overflow and resultant heap-based buffer overflow in zipOpenNewFileInZip4_64 via a long filename, comment, or extra field. NOTE: MiniZip is not a supported part of the zlib product.
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Analysis
by VulDB Data Team • 10/19/2024
The vulnerability CVE-2023-45853 represents a critical integer overflow issue within the MiniZip component of zlib version 1.3 and earlier. This flaw manifests in the zipOpenNewFileInZip4_64 function when processing long filenames, comments, or extra fields within zip archives. The vulnerability stems from inadequate input validation and arithmetic overflow handling in the compression library's archive creation routines. MiniZip serves as a supplementary utility for zlib but is not officially supported as part of the core zlib product, yet it remains widely used in various applications and systems. The integer overflow occurs when the system attempts to calculate memory allocation sizes for archive metadata, leading to insufficient buffer allocation that subsequently results in heap-based buffer overflow conditions.
The technical implementation of this vulnerability involves the manipulation of archive metadata fields that exceed normal size limitations. When a malicious actor provides excessively long filenames, comments, or extra field data, the integer arithmetic used to determine buffer sizes wraps around due to overflow conditions. This creates a scenario where the allocated buffer becomes smaller than required, allowing subsequent write operations to overwrite adjacent memory regions. The heap-based nature of the overflow means that attackers can potentially corrupt heap metadata, leading to arbitrary code execution or denial of service conditions. The vulnerability is particularly concerning because it can be exploited through legitimate archive creation operations, making it difficult to distinguish between normal and malicious usage patterns.
The operational impact of CVE-2023-45853 extends beyond simple archive processing as it affects any system or application that relies on zlib's MiniZip functionality for zip archive creation. This includes web applications, file processing systems, backup solutions, and network protocols that utilize zip compression. Attackers could leverage this vulnerability to execute remote code on affected systems, particularly in environments where zip files are automatically processed or decompressed without proper validation. The lack of official support for MiniZip means that many organizations may not be aware of this vulnerability or its potential impact. Systems using older versions of zlib are particularly at risk, as the vulnerability has existed since the introduction of the affected functions. The exploitability is enhanced by the fact that many applications automatically process zip files without implementing additional input sanitization measures, creating multiple attack vectors across different software domains.
Mitigation strategies for CVE-2023-45853 primarily focus on immediate version upgrades to zlib 1.3 or later where the vulnerability has been addressed. Organizations should conduct comprehensive inventory assessments to identify all systems using zlib and MiniZip components, particularly those handling user-supplied zip files. Input validation measures should be implemented at application layers to limit filename, comment, and extra field lengths before they reach the zlib library functions. The ATT&CK framework categorizes this vulnerability under T1203 - Exploitation for Client Execution, as it enables attackers to execute code through archive processing. Security teams should also implement network monitoring to detect unusual zip file processing activities and consider deploying web application firewalls that can filter malicious archive content. Additionally, the CWE database classifies this issue under CWE-190 - Integer Overflow or Wraparound, which provides a standardized reference for understanding the underlying root cause. Organizations should also review their incident response procedures to ensure preparedness for potential exploitation of this vulnerability through archive-based attacks.