CVE-2007-5378 in Tk Toolkit
Summary
by MITRE
Buffer overflow in the FileReadGIF function in tkImgGIF.c for Tk Toolkit 8.4.12 and earlier, and 8.3.5 and earlier, allows user-assisted attackers to cause a denial of service (segmentation fault) via an animated GIF in which the first subimage is smaller than a subsequent subimage, which triggers the overflow in the ReadImage function, a different vulnerability than CVE-2007-5137.
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Analysis
by VulDB Data Team • 07/28/2019
The vulnerability described in CVE-2007-5378 represents a critical buffer overflow condition within the Tk Toolkit's GIF image processing functionality. This flaw exists in the FileReadGIF function located in tkImgGIF.c and affects versions 8.4.12 and earlier, as well as 8.3.5 and earlier of the Tk Toolkit. The vulnerability operates through a specific sequence involving animated GIF files where the first subimage is deliberately smaller than subsequent subimages in the animation sequence. This particular configuration triggers a buffer overflow during the ReadImage function execution, creating a path for malicious exploitation that results in system instability.
The technical mechanism behind this vulnerability involves improper bounds checking within the image processing pipeline of the Tk Toolkit. When processing animated GIF files, the toolkit fails to adequately validate the dimensions and memory allocation requirements of successive subimages within the animation. The buffer overflow occurs because the system allocates memory based on the initial subimage size but does not account for subsequent subimages that may exceed the originally allocated buffer space. This mismatch between allocated memory and actual data requirements creates a classic buffer overflow condition that can be triggered by carefully crafted animated GIF files.
From an operational impact perspective, this vulnerability enables user-assisted denial of service attacks that can cause segmentation faults and system crashes. The attack requires an attacker to provide a specially crafted animated GIF file that demonstrates the dimensional inconsistency between subimages, which then triggers the buffer overflow in the ReadImage function. Systems running affected versions of Tk Toolkit are vulnerable when they process or display these malicious GIF files, potentially leading to complete application crashes or system instability. The vulnerability is particularly concerning in environments where users can upload or view images, as it can be exploited to disrupt normal operations without requiring elevated privileges.
The security implications of CVE-2007-5378 align with CWE-121, which describes heap-based buffer overflow conditions, and relates to the broader category of memory safety vulnerabilities that have been extensively documented in the cybersecurity community. This vulnerability demonstrates the importance of proper input validation and memory management in multimedia processing libraries, as it affects a fundamental component of graphical user interface toolkits. The attack vector involves user-assisted exploitation, meaning that the vulnerability requires user interaction to be triggered, but does not require complex attack infrastructure or elevated privileges.
Mitigation strategies for this vulnerability involve immediate upgrading to patched versions of the Tk Toolkit where the buffer overflow has been addressed through proper bounds checking and memory allocation validation. Organizations should also implement input validation measures that filter or reject animated GIF files with inconsistent subimage dimensions, particularly in environments where user uploads are permitted. Additionally, deploying application sandboxing techniques and restricting the processing of untrusted image files can provide additional layers of protection. The vulnerability underscores the need for comprehensive security testing of multimedia processing components and highlights the importance of maintaining up-to-date software libraries to prevent exploitation of known buffer overflow conditions. This type of vulnerability is often categorized under the ATT&CK technique T1203, which covers exploitation of software vulnerabilities, and represents a common attack surface in GUI-based applications that process external image formats.