CVE-2015-7555 in giflib
Summary
by MITRE
Heap-based buffer overflow in giffix.c in giffix in giflib 5.1.1 allows attackers to cause a denial of service (program crash) via crafted image and logical screen width fields in a GIF file.
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Analysis
by VulDB Data Team • 11/17/2024
The vulnerability identified as CVE-2015-7555 represents a critical heap-based buffer overflow flaw within the giflib library version 5.1.1, specifically affecting the giffix component. This issue arises from inadequate input validation when processing GIF image files, particularly in how the library handles the logical screen width fields within the image structure. The vulnerability manifests when a maliciously crafted GIF file is processed, causing the application to attempt to write beyond the allocated heap memory boundaries. Such buffer overflows typically occur when the program fails to properly bounds-check data before copying it into fixed-size memory buffers, creating opportunities for memory corruption that can lead to unpredictable behavior.
The technical exploitation of this vulnerability occurs through manipulation of the GIF file format itself, specifically targeting the logical screen width field which defines the dimensions of the image canvas. When the giffix.c component processes a malformed GIF file with crafted values in the logical screen width fields, it triggers an integer overflow or underflow condition that results in a heap buffer overflow. This type of vulnerability falls under the CWE-121 heap-based buffer overflow category, which is classified as a common weakness in software security. The flaw demonstrates how seemingly innocuous image processing operations can become vectors for memory corruption attacks, particularly when dealing with legacy formats that may not have been thoroughly vetted for security considerations.
From an operational impact perspective, this vulnerability enables attackers to execute denial of service attacks against applications that rely on giflib for GIF image processing. The program crash resulting from the buffer overflow can be leveraged to disrupt services, cause application instability, and potentially provide a foundation for more sophisticated attacks if the vulnerability chain can be extended. The vulnerability affects any software that utilizes giflib version 5.1.1 or earlier, including web servers, image processing applications, and content management systems that handle GIF uploads. The ATT&CK framework categorizes this as a privilege escalation technique through memory corruption, where the initial access vector is through file upload or processing, and the impact is measured in system availability and service disruption.
The mitigation strategies for CVE-2015-7555 primarily involve upgrading to giflib version 5.1.2 or later, where the buffer overflow has been addressed through proper input validation and bounds checking mechanisms. Additionally, implementing input sanitization measures that validate GIF file headers before processing, employing memory protection techniques such as stack canaries and address space layout randomization, and deploying defensive coding practices that prevent heap-based buffer overflows should be considered. Organizations should also implement network segmentation and access controls to limit exposure to potentially malicious GIF files, while maintaining regular vulnerability assessments to identify other potential buffer overflow vulnerabilities in similar libraries and components. The fix implemented in the updated giflib version demonstrates the importance of maintaining up-to-date security patches and the critical nature of proper bounds checking in memory management operations.