CVE-2015-4496 in Firefox
Summary
by MITRE
Multiple integer overflows in libstagefright in Mozilla Firefox before 38.0 allow remote attackers to execute arbitrary code via crafted sample metadata in an MPEG-4 video file.
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Analysis
by VulDB Data Team • 06/09/2022
The vulnerability identified as CVE-2015-4496 represents a critical security flaw within Mozilla Firefox's media processing subsystem known as libstagefright. This vulnerability affects versions of Firefox prior to 38.0 and stems from improper handling of integer overflow conditions during the parsing of MPEG-4 video files. The flaw specifically manifests when the browser encounters crafted sample metadata within video files, creating a condition where integer arithmetic operations exceed their maximum representable values. Such integer overflows create predictable memory corruption patterns that malicious actors can exploit to gain control over the affected system.
The technical implementation of this vulnerability involves the libstagefright component which serves as the core media decoding engine for Firefox's multimedia support. When processing MPEG-4 video files, the system performs various arithmetic operations to calculate buffer sizes, frame dimensions, and other metadata values. An attacker can manipulate the sample metadata within a malicious video file to trigger integer overflow conditions that result in insufficient buffer allocation or incorrect memory calculations. These overflows occur in contexts where the application assumes that integer operations will produce values within expected ranges, but instead receives values that wrap around to extremely large or negative numbers. This behavior creates exploitable memory corruption scenarios that can be leveraged for code execution.
The operational impact of CVE-2015-4496 extends beyond simple remote code execution capabilities, as it represents a sophisticated attack vector that can be delivered through standard web browsing activities. Attackers can craft malicious MPEG-4 video files containing specially designed metadata that triggers the integer overflow conditions when Firefox attempts to decode and display the content. The vulnerability's remote exploitability means that users can be compromised simply by visiting websites that host the malicious content or by downloading and opening the crafted video files. The attack surface includes web browsers, media players, and any application that relies on the vulnerable libstagefright library, making it particularly dangerous in enterprise environments where user exposure to untrusted content is common.
Security researchers have classified this vulnerability according to the Common Weakness Enumeration framework under the category of integer overflow conditions, specifically CWE-190, which describes integer overflows that can lead to memory corruption. The vulnerability also aligns with ATT&CK framework techniques related to privilege escalation and code injection, as successful exploitation can result in arbitrary code execution with the privileges of the affected browser process. The remediation strategy for this vulnerability requires immediate patching of Firefox installations to version 38.0 or later, which includes fixes for the integer overflow conditions in libstagefright. Organizations should implement comprehensive patch management procedures to ensure all affected systems are updated promptly, as the vulnerability remains exploitable in older versions of the browser.
The broader implications of CVE-2015-4496 highlight the ongoing challenges in securing multimedia processing libraries within web browsers, where complex media formats can introduce numerous attack vectors through seemingly innocuous parsing operations. The vulnerability demonstrates how mathematical operations in media decoders can create exploitable conditions when proper input validation and overflow checking are absent. Security professionals should consider implementing additional protective measures such as sandboxing mechanisms, content filtering, and network-based intrusion detection systems to mitigate the risk of exploitation while awaiting patch deployment. The incident also underscores the importance of regular security assessments of multimedia libraries and the need for robust input validation across all code paths that process external data streams.