CVE-2005-2096 in Solaris
Summary
by MITRE
zlib 1.2 and later versions allows remote attackers to cause a denial of service (crash) via a crafted compressed stream with an incomplete code description of a length greater than 1, which leads to a buffer overflow, as demonstrated using a crafted PNG file.
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability identified as CVE-2005-2096 represents a critical buffer overflow flaw within the zlib compression library version 1.2 and later. This issue specifically affects the decompression process when handling malformed compressed data streams, particularly those with incomplete code descriptions exceeding a length of one. The vulnerability stems from inadequate input validation within the decompression algorithm, where the library fails to properly sanitize compressed data before processing it. When zlib encounters a crafted compressed stream containing such malformed code descriptions, it attempts to allocate memory based on incorrect length parameters, resulting in memory corruption that ultimately leads to application crashes. The exploitability of this vulnerability is particularly concerning as it can be triggered remotely through the processing of maliciously crafted compressed files, making it a significant threat to systems that rely on zlib for decompression operations.
The technical implementation of this vulnerability demonstrates a classic buffer overflow condition where the decompression routine does not adequately check the bounds of compressed data structures. According to CWE-121, this vulnerability maps to a stack-based buffer overflow condition that occurs when data is copied into a buffer without proper bounds checking. The flaw specifically affects the Huffman decoding process within zlib where length codes are processed during decompression. When a compressed stream contains a length code that exceeds the expected parameters, the decompression algorithm continues processing without proper validation, leading to memory corruption. This behavior is consistent with ATT&CK technique T1203 which describes the exploitation of memory corruption vulnerabilities through malformed input data. The vulnerability is particularly dangerous because it can be triggered through common file formats such as PNG files, which utilize zlib compression for image data compression.
The operational impact of CVE-2005-2096 extends beyond simple denial of service conditions to potentially enable more sophisticated attack vectors. Systems that process user-uploaded files, web applications handling compressed data, or network services that decompress received data are all at risk of experiencing crashes or system instability. The vulnerability affects a wide range of applications including web browsers, image processing software, and network protocols that rely on zlib compression. When exploited successfully, this vulnerability can cause applications to terminate unexpectedly, potentially leading to service disruption or creating opportunities for further exploitation. The remote nature of the attack means that attackers can trigger the vulnerability without requiring local access to the target system, making it particularly dangerous in networked environments. Additionally, the vulnerability's presence in zlib 1.2 and later versions indicates that it affects a substantial portion of systems that utilize this widely deployed compression library.
Mitigation strategies for CVE-2005-2096 primarily focus on updating to patched versions of zlib where the decompression routine has been hardened against malformed input data. System administrators should prioritize updating all affected applications that utilize zlib, particularly those handling user-provided compressed data. Implementing input validation at the application level can provide additional protection by sanitizing compressed data before passing it to zlib for decompression. Network-based mitigations include implementing content filtering to detect and block suspicious compressed files, particularly those with unusual compression patterns. Security monitoring should focus on detecting unusual application crashes or restarts that may indicate exploitation attempts. Organizations should also consider implementing sandboxing techniques for decompression operations and establishing strict limits on file size and compression ratios to reduce the attack surface. The vulnerability highlights the importance of maintaining up-to-date third-party libraries and implementing robust input validation practices as recommended in industry standards such as NIST SP 800-53 and ISO 27001 security frameworks. Regular security assessments and vulnerability scanning should include checks for outdated zlib versions to prevent exploitation of this and similar memory corruption vulnerabilities.