CVE-2008-0553 in TCL TK
Summary
by MITRE
Stack-based buffer overflow in the ReadImage function in tkImgGIF.c in Tk (Tcl/Tk) before 8.5.1 allows remote attackers to execute arbitrary code via a crafted GIF image, a similar issue to CVE-2006-4484.
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Analysis
by VulDB Data Team • 08/05/2019
The vulnerability identified as CVE-2008-0553 represents a critical stack-based buffer overflow within the Tk graphical user interface toolkit's GIF image parsing functionality. This flaw exists in the ReadImage function located in the tkImgGIF.c source file, affecting Tk versions prior to 8.5.1. The vulnerability stems from inadequate input validation when processing specially crafted GIF image files, creating a condition where attacker-controlled data can overwrite adjacent memory locations on the stack. The issue is particularly dangerous because it allows remote code execution, meaning an attacker could potentially compromise systems simply by enticing users to view a maliciously crafted GIF image through an application built on Tk.
The technical nature of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite stack memory. The flaw operates by manipulating the GIF image format's structure to exceed the allocated buffer space during image parsing operations. When the ReadImage function processes a malformed GIF header or image data, it fails to properly validate the size parameters of image dimensions or color table entries, leading to memory corruption. This type of vulnerability is classified under the ATT&CK framework as a code injection technique, specifically leveraging buffer overflow primitives to execute arbitrary code within the context of the vulnerable application.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise when exploited successfully. Applications that utilize Tk for image display functionality become potential attack vectors, including web browsers, desktop applications, and any software that embeds Tcl/Tk components for graphical interfaces. The vulnerability is particularly concerning because it can be triggered through legitimate image viewing operations, making it difficult to detect and prevent through traditional network monitoring. Attackers can craft GIF files that, when processed by vulnerable applications, will overwrite return addresses, function pointers, or other critical stack variables, potentially allowing them to redirect program execution flow to malicious payloads.
Mitigation strategies for CVE-2008-0553 primarily focus on immediate version upgrades to Tk 8.5.1 or later, which contain the necessary patches to address the buffer overflow conditions. Organizations should conduct comprehensive vulnerability assessments to identify all systems running vulnerable versions of Tk and prioritize remediation efforts accordingly. Additionally, implementing input validation controls at application boundaries can provide defense-in-depth measures, though these are not sufficient to fully protect against the vulnerability. Network-based protections such as web application firewalls can be configured to filter out suspicious GIF content, though this approach requires careful configuration to avoid false positives. The vulnerability's similarity to CVE-2006-4484 indicates a pattern of repeated buffer overflow issues in image processing libraries, emphasizing the importance of proper memory management and input validation practices in multimedia handling components. Security teams should also consider implementing runtime protections such as stack canaries or address space layout randomization to reduce the exploitability of similar buffer overflow vulnerabilities in the broader system landscape.