CVE-2018-18828 in libav
Summary
by MITRE
There exists a heap-based buffer overflow in vc1_decode_i_block_adv in vc1_block.c in Libav 12.3, which allows attackers to cause a denial-of-service via a crafted aac file.
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Analysis
by VulDB Data Team • 04/07/2020
The heap-based buffer overflow vulnerability identified as CVE-2018-18828 resides within the Libav multimedia framework version 12.3, specifically in the vc1_decode_i_block_adv function located in vc1_block.c. This flaw represents a critical security weakness that can be exploited through maliciously crafted audio files with aac extension, potentially leading to system instability and denial-of-service conditions. The vulnerability stems from inadequate input validation and memory management practices within the video codec processing pipeline, particularly when handling VC1 (Windows Media Video 9) format data structures.
The technical implementation of this vulnerability occurs during the decoding process of VC1 video blocks where the function vc1_decode_i_block_adv fails to properly bounds-check array accesses when processing inter-block data. Attackers can manipulate the AAC file structure to trigger a heap overflow condition, causing memory corruption that may result in program termination or arbitrary code execution. The flaw manifests when the decoder attempts to write data beyond the allocated heap buffer boundaries, creating a condition where adjacent memory regions become corrupted. This type of vulnerability falls under CWE-121 heap-based buffer overflow, which is classified as a memory safety issue in the Common Weakness Enumeration catalog. The attack vector is particularly concerning as it requires minimal user interaction beyond opening the malicious file, making it suitable for automated exploitation scenarios.
The operational impact of CVE-2018-18828 extends beyond simple denial-of-service conditions, as it represents a potential pathway for more sophisticated attacks within multimedia processing environments. Systems utilizing Libav for audio/video processing, including media servers, content delivery networks, and multimedia applications, face significant risk from this vulnerability. The exploitation can lead to service disruption across multiple platforms where Libav is integrated, particularly affecting applications that process untrusted media content. According to ATT&CK framework methodology, this vulnerability maps to T1203 - Exploitation for Client Execution, as it enables remote code execution through media file manipulation. The vulnerability affects systems running Libav 12.3 and potentially other versions within the same codebase, making it a widespread concern for organizations maintaining legacy multimedia processing infrastructure.
Mitigation strategies for CVE-2018-18828 require immediate implementation of software updates and patches from Libav maintainers, as the vulnerability cannot be effectively addressed through configuration changes alone. Organizations should implement strict input validation for all multimedia files processed through affected systems, employing sandboxing techniques to isolate media processing operations from core system functions. Network-based mitigations include implementing content filtering rules that prevent execution of known malicious media formats, while endpoint protection solutions should be configured to monitor for unusual memory allocation patterns during media processing. The recommended approach involves upgrading to patched versions of Libav or migrating to alternative multimedia frameworks that have addressed similar memory safety issues. Security monitoring should focus on identifying abnormal process behavior, memory corruption indicators, and unauthorized file access patterns that may signal exploitation attempts. System administrators should also consider implementing automated patch management processes to ensure timely deployment of security updates across all affected systems and applications.