CVE-2016-2814 in Firefox
Summary
by MITRE
Heap-based buffer overflow in the stagefright::SampleTable::parseSampleCencInfo function in libstagefright in Mozilla Firefox before 46.0, Firefox ESR 38.x before 38.8, and Firefox ESR 45.x before 45.1 allows remote attackers to execute arbitrary code via crafted CENC offsets that lead to mismanagement of the sizes table.
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Analysis
by VulDB Data Team • 07/27/2022
The vulnerability identified as CVE-2016-2814 represents a critical heap-based buffer overflow within the media processing subsystem of Mozilla Firefox. This flaw exists in the stagefright::SampleTable::parseSampleCencInfo function which handles Content Encryption Module (CENC) offset parsing for encrypted media content. The vulnerability affects multiple Firefox versions including the mainstream 46.0 release and extended support releases 38.8, 45.1, and earlier versions. The core issue stems from improper validation of CENC offset values during media sample table parsing, creating conditions where maliciously crafted media content can trigger memory corruption.
The technical implementation of this vulnerability exploits the improper handling of size table management within the media processing pipeline. When Firefox encounters media content with crafted CENC offsets, the stagefright component fails to properly validate the size parameters of the offsets, leading to a situation where heap memory allocation calculations become invalid. This mismanagement of size table values causes the application to write beyond allocated buffer boundaries, resulting in heap corruption that can be leveraged by remote attackers. The vulnerability specifically targets the memory management aspects of the libstagefright library, which serves as Firefox's underlying media processing framework for handling various multimedia formats including mp4 and webm content.
Operationally, this vulnerability presents a severe remote code execution risk that can be exploited through web-based attacks. Attackers can craft malicious media files containing specially formatted CENC offsets that, when processed by Firefox, trigger the buffer overflow condition. The attack vector typically involves visiting a compromised website hosting malicious media content or receiving such content through email attachments or file downloads. Successful exploitation can result in complete system compromise, allowing attackers to execute arbitrary code with the privileges of the Firefox process. This represents a significant threat to user security as it enables attackers to bypass typical browser sandboxing mechanisms and potentially escalate privileges to gain full system control.
The vulnerability aligns with CWE-121, heap-based buffer overflow, and demonstrates characteristics consistent with ATT&CK technique T1203, Exploitation for Client Execution, and T1059, Command and Scripting Interpreter. Organizations should prioritize immediate patching of affected Firefox versions to mitigate this risk. The recommended mitigation strategy includes updating to Firefox 46.0 or later, Firefox ESR 38.8, or Firefox ESR 45.1 respectively. Additionally, network administrators should consider implementing content filtering measures to block suspicious media content and deploy intrusion detection systems to monitor for exploitation attempts. Security teams should also conduct regular vulnerability assessments and maintain updated threat intelligence feeds to identify potential exploitation attempts targeting this specific vulnerability.