CVE-2012-3425 in libpng
Summary
by MITRE
The png_push_read_zTXt function in pngpread.c in libpng 1.0.x before 1.0.58, 1.2.x before 1.2.48, 1.4.x before 1.4.10, and 1.5.x before 1.5.10 allows remote attackers to cause a denial of service (out-of-bounds read) via a large avail_in field value in a PNG image.
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Analysis
by VulDB Data Team • 12/07/2021
The vulnerability identified as CVE-2012-3425 represents a critical out-of-bounds read flaw within the libpng library implementation that affects multiple version streams including 1.0.x prior to 1.0.58, 1.2.x prior to 1.2.48, 1.4.x prior to 1.4.10, and 1.5.x prior to 1.5.10. This issue manifests in the png_push_read_zTXt function located within the pngpread.c source file, where the library fails to properly validate input parameters before processing compressed text chunks within png image files. The flaw specifically exploits the handling of the avail_in field value which represents the available input data size during decompression operations, allowing malicious actors to craft specially formatted png images that trigger memory access violations.
The technical exploitation of this vulnerability occurs when a png image contains a malformed zTXt chunk with an excessively large avail_in field value that exceeds the actual data buffer boundaries. During decompression processing, the libpng library attempts to read beyond allocated memory regions, resulting in an out-of-bounds memory access pattern that can lead to application crashes or unpredictable behavior. This type of vulnerability falls under CWE-129 Input Validation and Output Generation, specifically manifesting as an improper input validation issue where the library does not adequately check the bounds of user-provided data before processing. The vulnerability directly maps to attack techniques categorized under ATT&CK tactic TA0005 Defense Evasion and TA0006 Credential Access, as it can be leveraged to disrupt services and potentially enable further exploitation vectors.
The operational impact of CVE-2012-3425 extends beyond simple denial of service conditions, as it represents a significant security risk for any application or system that processes png image files without proper input sanitization. Attackers can leverage this vulnerability to cause widespread service disruption across web applications, image processing systems, and any software that relies on libpng for png file handling. The vulnerability is particularly dangerous in web environments where users can upload arbitrary png files, as it can be exploited to crash web servers, cause application instability, or potentially enable more sophisticated attacks if combined with other vulnerabilities. The out-of-bounds read condition creates an opportunity for memory corruption that may allow attackers to execute arbitrary code under certain circumstances, especially when combined with other memory-related vulnerabilities in the same application stack.
Mitigation strategies for CVE-2012-3425 require immediate patching of affected libpng versions to the latest stable releases that contain the necessary input validation fixes. System administrators should prioritize updating all applications and services that utilize libpng to ensure they are running patched versions of the library. Additionally, implementing input validation measures at application layers can provide defense-in-depth protection, including validating image file headers, limiting file sizes, and employing sandboxed processing environments for image handling operations. Network-based mitigations such as content filtering and web application firewalls can help detect and block malicious png files before they reach vulnerable applications. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates across all affected systems and applications that depend on libpng functionality. The vulnerability demonstrates the critical importance of maintaining up-to-date third-party libraries and implementing comprehensive security testing procedures that include static analysis and dynamic testing of input handling routines.