CVE-2015-4493 in Firefox
Summary
by MITRE
Heap-based buffer overflow in the stagefright::ESDS::parseESDescriptor function in libstagefright in Mozilla Firefox before 40.0 and Firefox ESR 38.x before 38.2 allows remote attackers to execute arbitrary code via an invalid size field in an esds chunk in MPEG-4 video data, a related issue to CVE-2015-1539.
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Analysis
by VulDB Data Team • 10/22/2024
The heap-based buffer overflow vulnerability identified as CVE-2015-4493 resides within the stagefright multimedia framework component of Mozilla Firefox browsers. This flaw specifically affects the stagefright::ESDS::parseESDescriptor function in the libstagefright library, which processes MPEG-4 video data containing esds (elementary stream descriptor) chunks. The vulnerability represents a critical security flaw that enables remote code execution when maliciously crafted MPEG-4 video files are processed by affected browser versions. The issue stems from inadequate input validation of the size field within the esds chunk structure, allowing attackers to manipulate memory allocation parameters and subsequently overwrite adjacent heap memory regions.
The technical exploitation of this vulnerability occurs when Firefox encounters an MPEG-4 video file with a malformed esds chunk containing an invalid size field value. During parsing, the stagefright::ESDS::parseESDescriptor function attempts to allocate heap memory based on the malformed size field, creating a buffer that is insufficient to accommodate the actual data being processed. This heap-based buffer overflow enables attackers to overwrite critical memory locations including return addresses, function pointers, or other control data structures, thereby allowing arbitrary code execution with the privileges of the compromised browser process. The vulnerability demonstrates characteristics consistent with CWE-121 heap-based buffer overflow, specifically CWE-129, which deals with insufficient size checks for memory allocation. The flaw operates within the context of multimedia processing and represents a classic example of how malformed media file structures can be weaponized for remote code execution.
The operational impact of CVE-2015-4493 extends beyond simple browser compromise, as it enables attackers to execute arbitrary code on vulnerable systems without requiring user interaction beyond visiting a malicious website or opening a compromised media file. This vulnerability affects both regular Firefox releases and Firefox Extended Support Release versions, creating a widespread attack surface across multiple deployment environments. The attack vector is particularly dangerous because it leverages the browser's multimedia processing capabilities, which are commonly enabled by default in modern web browsers. This allows attackers to achieve remote code execution through simple web-based attacks, making the vulnerability highly exploitable in real-world scenarios. The vulnerability's relationship to CVE-2015-1539 demonstrates a pattern of similar flaws within the stagefright framework, indicating a broader architectural weakness in the multimedia processing components that require comprehensive remediation.
Mitigation strategies for CVE-2015-4493 primarily focus on immediate browser updates to versions that contain patches addressing the heap overflow in the stagefright library. Users should immediately upgrade to Firefox 40.0 or Firefox ESR 38.2 and later versions where the vulnerability has been resolved through proper input validation of size fields in esds chunks. Organizations should implement network-based mitigations including content filtering and media file validation to prevent exploitation attempts. The patch implementation addresses the core issue by introducing proper bounds checking and size validation within the stagefright::ESDS::parseESDescriptor function, ensuring that heap allocations are properly constrained based on verified input data. Security teams should also consider implementing monitoring for suspicious network traffic patterns that might indicate exploitation attempts targeting this vulnerability. Additionally, browser hardening measures such as heap protection mechanisms and address space layout randomization can provide additional defense-in-depth protection against potential exploitation attempts. The vulnerability highlights the importance of robust input validation in multimedia processing components and serves as a reminder of the critical security considerations required in media handling libraries that process untrusted data from web sources.