CVE-2004-0999 in Image Viewer
Summary
by MITRE
zgv 5.5.3 allows remote attackers to cause a denial of service (application crash via segmentation fault) via crafted multiple-image (animated) GIF images.
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Analysis
by VulDB Data Team • 06/02/2019
The vulnerability identified as CVE-2004-0999 affects zgv version 5.5.3, a command-line image viewer for unix-like systems that supports various image formats including gif. This particular flaw represents a denial of service condition that can be triggered remotely through the manipulation of image files, specifically animated gif images. The vulnerability stems from inadequate input validation and memory handling within the gif parsing component of the application. When zgv encounters specially crafted animated gif files containing malformed or excessively complex image data structures, the application fails to properly process these inputs and subsequently crashes with a segmentation fault, rendering the application unusable for legitimate image viewing operations.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers buffer overflow vulnerabilities in heap data structures. The flaw manifests when the gif parser attempts to handle multiple image frames or complex image data sequences that exceed expected memory allocation boundaries. The attacker can construct gif files with malformed frame dimensions, excessive color table entries, or recursive data structures that cause the memory management routines to fail. This type of vulnerability falls under the ATT&CK technique T1499.004, which involves network denial of service attacks through application layer attacks, where the attacker leverages application-specific parsing flaws to disrupt service availability.
The operational impact of this vulnerability extends beyond simple application instability as it can be exploited in environments where zgv is used for automated image processing or as part of larger systems. Remote attackers can potentially disrupt services by uploading or delivering malicious gif files to systems running vulnerable versions of zgv, leading to service interruption and requiring manual intervention to restore normal operations. In server environments or automated systems where zgv is used for image display or processing, this vulnerability could be particularly dangerous as it may allow attackers to systematically disrupt image viewing services or cause cascading failures in dependent applications. The vulnerability also demonstrates the importance of proper input sanitization and memory management in image processing libraries, as similar issues have been observed in other graphics libraries and image viewers.
Mitigation strategies for this vulnerability primarily involve immediate patching of the affected zgv version to a patched release that properly handles malformed gif inputs. Organizations should implement input validation measures that reject or sanitize gif files before processing, particularly those with unusual frame counts or complex data structures. Network-level protections such as content filtering and file type validation can help prevent malicious gif files from reaching systems running zgv. Additionally, implementing application sandboxing or containerization for image viewing applications can limit the impact of such vulnerabilities by isolating the affected processes from critical system resources. Regular security auditing of image processing components and maintaining updated versions of graphics libraries can help prevent similar vulnerabilities from being exploited in other applications that rely on similar parsing mechanisms. The vulnerability also underscores the need for proper software testing procedures that include fuzzing and input validation testing to identify potential buffer overflow conditions in multimedia processing applications.