CVE-2022-21917: Microsoft HEVC Video Extensions RCE Flaw

CVE-2022-21917 Overview

CVE-2022-21917 is a remote code execution vulnerability affecting Microsoft HEVC Video Extensions. This vulnerability allows attackers to execute arbitrary code on vulnerable systems through specially crafted media files. The flaw exists in the way HEVC Video Extensions handles malformed video content, potentially enabling threat actors to compromise systems when users open or preview malicious HEVC-encoded video files.

Critical Impact

Successful exploitation could allow attackers to execute arbitrary code with the privileges of the current user, potentially leading to complete system compromise if the user has administrative rights.

Affected Products

• Microsoft HEVC Video Extensions

Discovery Timeline

• 2022-01-11 - CVE-2022-21917 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-21917

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-Bounds Write), a memory corruption vulnerability that occurs when the HEVC Video Extensions codec processes malformed video content. The flaw requires local access to the target system and user interaction, typically through the victim opening a specially crafted HEVC video file. Once triggered, the out-of-bounds write condition can corrupt adjacent memory, potentially allowing an attacker to overwrite critical data structures or inject malicious code into the process memory space.

The attack complexity is low, meaning exploitation does not require sophisticated techniques once a victim interacts with the malicious file. Successful exploitation results in high impact to confidentiality, integrity, and availability, as the attacker gains the ability to read sensitive data, modify system files, and potentially cause system crashes or denial of service.

Root Cause

The root cause of this vulnerability stems from improper bounds checking when parsing HEVC (High Efficiency Video Coding) encoded video streams. During the decoding process, the codec fails to properly validate input data before writing to memory buffers, resulting in an out-of-bounds write condition. This type of memory corruption vulnerability can occur when processing specially crafted video headers, frame data, or metadata that contains unexpected or malicious values designed to trigger the boundary violation.

Attack Vector

The attack vector is local, requiring an attacker to deliver a malicious HEVC video file to the victim. This could be accomplished through various delivery mechanisms including email attachments, file-sharing platforms, malicious websites, or removable media. The vulnerability requires user interaction—the victim must open, preview, or otherwise process the malicious video file for exploitation to occur.

When the victim opens the crafted video file, the HEVC Video Extensions codec attempts to parse and decode the content. The malformed data triggers the out-of-bounds write condition, allowing the attacker to corrupt memory and potentially achieve code execution within the context of the application or user session.

Detection Methods for CVE-2022-21917

Indicators of Compromise

• Unexpected crashes or errors in applications attempting to render HEVC video content
• Suspicious HEVC video files with unusual file structures or metadata in user download directories
• Memory access violations or application exceptions related to video codec processing
• Unusual child processes spawned from Windows Media-related components

Detection Strategies

• Monitor for unexpected process behavior when video files are accessed or previewed
• Implement endpoint detection rules to identify anomalous memory operations during video decoding
• Deploy file scanning solutions capable of identifying malformed HEVC video structures
• Enable crash reporting and analyze dumps for signs of memory corruption exploitation attempts

Monitoring Recommendations

• Configure endpoint security solutions to monitor HEVC codec activity and report suspicious behavior
• Implement file reputation services to flag potentially malicious video files before user access
• Enable Windows Event logging for application crashes and correlate with video file access events
• Monitor network traffic for suspicious downloads of HEVC video files from untrusted sources

How to Mitigate CVE-2022-21917

Immediate Actions Required

• Update Microsoft HEVC Video Extensions to the latest patched version via Microsoft Store
• Restrict access to untrusted video files, particularly those received from unknown sources
• Implement application whitelisting to control which applications can process video content
• Educate users about the risks of opening video files from untrusted sources

Patch Information

Microsoft has released security updates to address this vulnerability. Users should update their HEVC Video Extensions through the Microsoft Store to obtain the patched version. Detailed information is available through the Microsoft Vulnerability Update for CVE-2022-21917 and the Microsoft Security Advisory. Additional technical details can be found in the Mandiant Vulnerability Disclosure MNDT-2022-0008.

Workarounds

• Consider uninstalling HEVC Video Extensions if not required for business operations
• Block HEVC video files at email gateways and web proxies until patches are applied
• Use alternative video codecs where possible for critical workflows
• Implement application isolation or sandboxing for video playback applications

# Check installed HEVC Video Extensions version via PowerShell
Get-AppxPackage -Name "Microsoft.HEVCVideoExtension*" | Select-Object Name, Version

# Force update of Microsoft Store apps (requires admin privileges)
Get-AppxPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}