CVE-2021-38644 in MPEG-2 Video Extension
Summary
by MITRE • 09/15/2021
Microsoft MPEG-2 Video Extension Remote Code Execution Vulnerability
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Analysis
by VulDB Data Team • 09/17/2021
The CVE-2021-38644 vulnerability represents a critical remote code execution flaw within Microsoft's MPEG-2 Video Extension component, which serves as a multimedia framework for processing video content on Windows operating systems. This vulnerability specifically affects the handling of malformed MPEG-2 video streams and occurs when the affected component processes untrusted video data without proper validation mechanisms. The flaw exists in the way the MPEG-2 decoder validates input parameters and manages memory allocation during video frame processing, creating a pathway for malicious actors to execute arbitrary code on vulnerable systems. The vulnerability is particularly concerning because it can be triggered through various attack vectors including email attachments, web downloads, or streaming content that utilizes the affected video extension.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-787, which covers out-of-bounds write operations. The flaw manifests when the MPEG-2 video extension receives specially crafted video data that causes the decoder to allocate insufficient memory buffers while processing video frames. This inadequate memory management allows attackers to overwrite adjacent memory locations with malicious code, potentially leading to full system compromise. The vulnerability is classified under the ATT&CK technique T1203, which involves exploiting software vulnerabilities for privilege escalation and code execution. The attack surface extends across multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it particularly dangerous for enterprise environments where these systems are prevalent.
The operational impact of CVE-2021-38644 extends beyond simple remote code execution to encompass complete system compromise and potential data exfiltration. Attackers can leverage this vulnerability to install backdoors, deploy ransomware, or establish persistent access to compromised systems without requiring user interaction or elevated privileges. The vulnerability's remote exploitation capability means that attackers can target systems from anywhere on the internet, making it a prime candidate for automated exploitation campaigns. Organizations running affected systems face significant risk of unauthorized access, data breaches, and potential lateral movement within their networks. The vulnerability's exploitation requires minimal user interaction beyond receiving malicious video content, making it particularly dangerous in environments where users frequently download or stream media content.
Mitigation strategies for CVE-2021-38644 should prioritize immediate patch deployment through Microsoft's regular security updates, which address the underlying memory handling flaws in the MPEG-2 video extension component. Organizations should implement network segmentation and firewall rules to restrict access to systems running the affected components, particularly those exposed to untrusted networks or users. Application whitelisting policies can help prevent exploitation by blocking unauthorized video processing applications from executing on vulnerable systems. Additionally, security teams should monitor network traffic for unusual video processing activities and implement endpoint detection and response solutions that can identify potential exploitation attempts. The vulnerability also highlights the importance of regular security assessments and penetration testing to identify similar flaws in multimedia processing components across the enterprise infrastructure.