CVE-2016-1957 in Firefox
Summary
by MITRE
Memory leak in libstagefright in Mozilla Firefox before 45.0 and Firefox ESR 38.x before 38.7 allows remote attackers to cause a denial of service (memory consumption) via an MPEG-4 file that triggers a delete operation on an array.
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Analysis
by VulDB Data Team • 07/09/2022
The vulnerability identified as CVE-2016-1957 represents a critical memory management flaw within Mozilla Firefox's media processing component known as libstagefright. This issue affects Firefox versions prior to 45.0 and Firefox ESR 38.x versions prior to 38.7, creating a significant security risk that can be exploited remotely. The flaw resides in how the browser handles MPEG-4 media files during parsing and processing operations, specifically within the stagefright framework that manages multimedia content delivery. The vulnerability manifests when a maliciously crafted MPEG-4 file is processed by Firefox, triggering an improper memory deallocation sequence that leads to progressive memory consumption.
The technical implementation of this vulnerability involves a memory leak condition that occurs during the deletion of array objects within the libstagefright library. When Firefox encounters an MPEG-4 file with specific malformed structures, the media parser attempts to delete array elements but fails to properly manage the memory allocation patterns. This improper deletion operation causes memory segments to remain allocated in the browser's memory space even after they should have been freed, resulting in gradual memory exhaustion. The flaw is classified under CWE-401 as a weakness in memory management, specifically related to improper deallocation of memory resources.
From an operational perspective, this vulnerability enables remote attackers to execute denial of service attacks against Firefox users by simply delivering a malicious MPEG-4 file through web content or email attachments. The attack requires no user interaction beyond viewing or downloading the media file, making it particularly dangerous in phishing campaigns or malicious websites. As the browser continues to process the malformed file, memory consumption increases progressively until system resources are exhausted, potentially causing the browser to crash or become unresponsive. This type of attack aligns with ATT&CK technique T1499.004 for network denial of service, where adversaries leverage application-level vulnerabilities to consume system resources.
The impact of this vulnerability extends beyond simple service disruption as it can affect system stability and user productivity. When exploited successfully, the memory leak can cause Firefox to consume all available memory on the system, leading to complete application failure and potentially affecting other running processes. The vulnerability also represents a significant concern for enterprise environments where users may be exposed to malicious content through various attack vectors including web browsing, email systems, and file downloads. Organizations using affected Firefox versions are particularly vulnerable since the flaw can be exploited through legitimate web browsing activities without any sophisticated attack techniques. Security professionals should consider this vulnerability when conducting risk assessments for browser-based attack surfaces and implementing defense-in-depth strategies to mitigate potential exploitation attempts.
Mitigation strategies for CVE-2016-1957 primarily involve updating Firefox installations to versions 45.0 or later for regular releases and 38.7 or later for ESR versions, which contain the necessary patches to address the memory leak condition. Additionally, organizations should implement web content filtering solutions that can detect and block malicious media files before they reach user browsers. Browser hardening measures including disabling automatic media playback and implementing strict content security policies can further reduce the attack surface. Security monitoring should include detection of unusual memory consumption patterns in browser processes, as these may indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of keeping multimedia processing libraries up to date and implementing comprehensive security measures for browser-based applications.