CVE-2016-1933 in Firefox
Summary
by MITRE
Integer overflow in the image-deinterlacing functionality in Mozilla Firefox before 44.0 allows remote attackers to cause a denial of service (memory consumption or application crash) via a crafted GIF image.
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Analysis
by VulDB Data Team • 07/06/2022
The vulnerability identified as CVE-2016-1933 represents a critical integer overflow flaw within Mozilla Firefox's image processing subsystem, specifically affecting the deinterlacing functionality used for handling gif images. This issue exists in Firefox versions prior to 44.0 and demonstrates how seemingly benign image processing operations can be exploited to create significant security impacts. The vulnerability stems from insufficient input validation and boundary checking within the gif deinterlacing algorithm, where integer arithmetic operations fail to properly handle overflow conditions that can occur when processing malformed image data.
The technical implementation of this vulnerability involves the manipulation of gif image headers and metadata to trigger arithmetic overflow conditions during memory allocation calculations. When Firefox encounters a crafted gif image, the deinterlacing routine attempts to calculate memory requirements for processing interlaced image data, but integer overflow occurs during these calculations. This overflow results in incorrect memory allocation sizes being computed, leading to either excessive memory consumption that can cause system resource exhaustion or memory corruption that triggers application crashes. The flaw operates at the intersection of image parsing and memory management, making it particularly dangerous as it can be exploited through web-based attacks without requiring user interaction beyond visiting a malicious website.
From an operational impact perspective, this vulnerability creates a remote denial of service condition that can be leveraged by attackers to disrupt Firefox users' browsing experience and potentially impact system stability. The memory consumption aspect of the attack can lead to system performance degradation or complete application crashes, while the crash mechanism can be used to repeatedly destabilize the browser. The vulnerability's remote exploitability means that attackers can craft malicious gif images and deliver them through web pages, email attachments, or other vector that can cause the target browser to process the malicious content. This makes it particularly dangerous in environments where users may encounter untrusted content, as the attack requires no specialized privileges or user interaction beyond normal browsing behavior.
Security researchers have classified this vulnerability according to CWE-190, which specifically addresses integer overflow conditions, and it aligns with ATT&CK technique T1203, covering the exploitation of memory corruption vulnerabilities. The flaw demonstrates the importance of robust input validation and proper integer arithmetic handling in multimedia processing libraries. Organizations should prioritize updating to Firefox 44.0 or later versions to remediate this vulnerability, as the patch addresses the underlying integer overflow conditions in the gif deinterlacing implementation. Additionally, implementing network-based security controls such as web application firewalls and content filtering systems can provide additional protection layers while awaiting full patch deployment. The vulnerability also underscores the need for comprehensive testing of image processing components and the importance of applying security patches promptly to prevent exploitation of similar issues in other browser components or third-party libraries.