CVE-2017-6314 in gdk-pixbuf
Summary
by MITRE
The make_available_at_least function in io-tiff.c in gdk-pixbuf allows context-dependent attackers to cause a denial of service (infinite loop) via a large TIFF file.
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Analysis
by VulDB Data Team • 10/15/2019
The vulnerability identified as CVE-2017-6314 resides within the gdk-pixbuf library's handling of TIFF image files, specifically in the make_available_at_least function located in io-tiff.c. This function is responsible for managing the availability of image data during the decoding process, and when processing malformed or specially crafted large TIFF files, it fails to properly validate input parameters. The flaw manifests as an infinite loop condition that causes the application to consume excessive CPU resources and eventually become unresponsive, creating a denial of service scenario that can be exploited by context-dependent attackers.
The technical implementation of this vulnerability stems from inadequate boundary checking and loop termination logic within the TIFF parsing code. When the make_available_at_least function processes a large TIFF file containing malformed data structures or excessive metadata, the internal loop mechanisms that manage data retrieval and processing fail to properly validate whether the loop conditions will eventually terminate. This weakness allows attackers to craft TIFF files with specific characteristics that cause the parsing routine to enter an infinite loop, where the function continuously processes the same data without making meaningful progress toward completing the image decoding operation. The vulnerability is particularly concerning because it can be triggered through normal image loading operations, making it difficult to distinguish between legitimate and malicious input.
From an operational impact perspective, this vulnerability affects any application that relies on gdk-pixbuf for image processing, including web browsers, image viewers, desktop applications, and server-side image processing systems. The denial of service condition can be exploited to consume system resources indefinitely, potentially leading to system instability or complete service unavailability. Attackers can leverage this vulnerability by simply providing a specially crafted TIFF file to any application that uses gdk-pixbuf, making it a particularly dangerous flaw in environments where users can upload or download image files. The vulnerability's context-dependent nature means that exploitation requires an application to be actively processing the malicious TIFF file, but the attack surface is broad due to gdk-pixbuf's widespread use across various software platforms.
Mitigation strategies for CVE-2017-6314 should focus on implementing proper input validation and resource limiting mechanisms within applications that utilize gdk-pixbuf. System administrators should ensure that all affected applications are updated to versions that contain the patched implementation of the make_available_at_least function, which typically includes proper loop termination conditions and input parameter validation. Additionally, implementing timeouts and resource usage monitoring can help detect and prevent exploitation attempts by limiting the amount of time and system resources that can be consumed during image processing operations. Organizations should also consider implementing file type validation and size limiting for image uploads to reduce the attack surface. This vulnerability aligns with CWE-835, which addresses infinite loops, and represents a classic example of how improper input validation can lead to resource exhaustion attacks, potentially mapping to ATT&CK technique T1499.001 for resource exhaustion through denial of service attacks.
The root cause of this vulnerability demonstrates the importance of robust input validation and proper error handling in image processing libraries, where malformed data can lead to unexpected program behavior. Security practitioners should recognize that this type of vulnerability is particularly challenging to detect through traditional static analysis due to its dependence on specific input conditions and the complex nature of image format parsing. The fix typically involves adding proper boundary checks and ensuring that loop conditions in the TIFF parsing code will always terminate under all possible input conditions, preventing the infinite loop scenario that leads to the denial of service condition.