CVE-2007-5266 in libpng
Summary
by MITRE
Off-by-one error in ICC profile chunk handling in the png_set_iCCP function in pngset.c in libpng before 1.0.29 beta1 and 1.2.x before 1.2.21 beta1 allows remote attackers to cause a denial of service (crash) via a crafted PNG image that prevents a name field from being NULL terminated.
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Analysis
by VulDB Data Team • 07/27/2019
The vulnerability identified as CVE-2007-5266 represents a critical off-by-one error within the libpng library's handling of ICC profile chunks during the png_set_iCCP function execution. This flaw exists in pngset.c file and affects libpng versions prior to 1.0.29 beta1 and 1.2.x versions before 1.2.21 beta1, making it a widespread issue across multiple library versions. The vulnerability stems from improper boundary checking when processing ICC profile data, specifically in how the library manages the name field within the profile chunk structure. When a maliciously crafted PNG image is processed, the function fails to properly null-terminate the name field, creating a condition where memory access boundaries are violated.
The technical implementation of this vulnerability involves the png_set_iCCP function's handling of ICC profile chunks where the library performs insufficient validation of input data lengths and memory boundaries. During the processing of the ICC profile data, the code attempts to copy profile name information into a buffer without adequate bounds checking, leading to an off-by-one error that can overwrite adjacent memory locations. This error occurs because the library assumes that the name field in the ICC profile will always be properly null-terminated, but when attackers craft PNG files with carefully constructed profile data, they can manipulate the data structure to bypass this assumption. The flaw specifically targets the memory management of string handling within the profile chunk processing, where the library's buffer overflow protection mechanisms are inadequate.
The operational impact of this vulnerability is significant as it allows remote attackers to execute denial of service attacks against systems that process PNG images. When a vulnerable application attempts to load a crafted PNG file containing malicious ICC profile data, the off-by-one error causes the application to crash or become unresponsive, effectively rendering the service unavailable to legitimate users. This vulnerability particularly affects web applications, image processing systems, and any software that relies on libpng for PNG file handling, as these systems can be exploited through simple image uploads or viewing operations. The crash occurs at the memory management level where the application's execution is interrupted due to invalid memory access patterns, making it difficult for the system to recover gracefully.
Mitigation strategies for CVE-2007-5266 primarily involve updating to patched versions of the libpng library where the off-by-one error has been corrected through proper bounds checking and null termination of string fields. System administrators should prioritize patching affected applications and libraries to prevent exploitation, as the vulnerability is easily exploitable through crafted image files. Additionally, implementing input validation measures at the application level can provide an extra layer of protection, though the most effective approach remains updating to patched library versions. Security monitoring should include detection of malformed PNG files being processed by applications, and network-level filtering can help prevent malicious image uploads. This vulnerability aligns with CWE-121, heap-based buffer overflow, and can be categorized under ATT&CK technique T1499.004 for denial of service, making it a critical target for security hardening and vulnerability management programs.