CVE-2023-36872: VP9 Video Extensions Info Disclosure Flaw

CVE-2023-36872 Overview

CVE-2023-36872 is an information disclosure vulnerability affecting Microsoft VP9 Video Extensions. This vulnerability allows an attacker to potentially access sensitive information from the affected system through improper input validation when processing VP9 video content. The attack requires local access and user interaction, making it a targeted exploitation scenario where a user must be tricked into opening a maliciously crafted video file.

Critical Impact

Successful exploitation of this vulnerability could lead to unauthorized disclosure of sensitive information from the affected system, potentially exposing confidential data to attackers with local access.

Affected Products

• Microsoft VP9 Video Extensions (all vulnerable versions)

Discovery Timeline

• July 11, 2023 - CVE-2023-36872 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-36872

Vulnerability Analysis

This information disclosure vulnerability resides in Microsoft's VP9 Video Extensions component, which is used for decoding VP9 video format content on Windows systems. The vulnerability stems from improper input validation (CWE-20) when processing VP9 encoded video data.

When a user opens a specially crafted VP9 video file, the extensions component fails to properly validate input boundaries, potentially allowing an attacker to read memory contents that should not be accessible. This could result in the exposure of sensitive system information or user data that resides in adjacent memory regions.

The attack scenario requires the victim to open a malicious video file on their local system, which could be delivered through phishing emails, malicious websites, or other social engineering techniques. While the vulnerability requires user interaction, the potential for high confidentiality impact makes it a significant concern for enterprise environments.

Root Cause

The root cause of CVE-2023-36872 is improper input validation (CWE-20) within the VP9 Video Extensions decoding routines. When processing video data, the component does not adequately validate or sanitize input parameters, allowing specially crafted video files to trigger out-of-bounds memory read operations. This improper handling of malformed input enables attackers to extract information from memory locations beyond the intended boundaries.

Attack Vector

The attack vector for this vulnerability is local, requiring an attacker to either have direct access to the target system or convince a user to open a malicious VP9 video file. The exploitation flow typically involves:

1. An attacker crafts a malicious VP9 video file containing specially formatted data designed to trigger the vulnerability
2. The malicious file is delivered to the victim through email attachments, malicious downloads, or removable media
3. When the victim opens the file using an application that leverages VP9 Video Extensions, the improper input validation is triggered
4. The vulnerability allows the attacker to potentially read sensitive information from the system's memory

The vulnerability mechanism centers on the input validation flaw in VP9 video parsing. Technical details are available in the Microsoft Security Update Guide.

Detection Methods for CVE-2023-36872

Indicators of Compromise

• Unusual VP9 video files with abnormal file structures or headers being accessed on endpoints
• Unexpected memory access patterns by video codec-related processes
• Applications processing VP9 content exhibiting abnormal behavior or crashes
• Presence of unfamiliar or suspicious video files in user download directories or temp folders

Detection Strategies

• Monitor for unusual process behavior associated with video codec extensions and media playback applications
• Implement endpoint detection rules to identify suspicious VP9 file access patterns
• Deploy SentinelOne Singularity to detect anomalous memory access patterns and exploitation attempts
• Utilize file integrity monitoring to detect unauthorized modification of VP9 Video Extensions components

Monitoring Recommendations

• Enable detailed logging for Windows media-related processes and codec operations
• Configure SentinelOne agents to alert on suspicious behavior from video processing applications
• Monitor for unusual outbound network activity following VP9 video file processing
• Implement behavioral analysis for media player and codec processes to detect anomalous information access

How to Mitigate CVE-2023-36872

Immediate Actions Required

• Apply the official Microsoft security update for VP9 Video Extensions immediately
• Verify the VP9 Video Extensions component is updated to the latest patched version via Microsoft Store
• Educate users about the risks of opening video files from untrusted sources
• Consider temporarily restricting VP9 video file handling in high-security environments until patching is complete

Patch Information

Microsoft has released a security update to address this vulnerability. The patch is available through the Microsoft Store as an automatic update to the VP9 Video Extensions component. Organizations should verify that automatic updates are enabled for Microsoft Store apps or manually update the VP9 Video Extensions through the Microsoft Store.

For detailed patch information and official guidance, refer to the Microsoft Security Update Guide for CVE-2023-36872.

Workarounds

• Temporarily disable or uninstall VP9 Video Extensions if the functionality is not required in your environment
• Implement strict email and web filtering to block suspicious video file attachments
• Utilize application whitelisting to prevent unauthorized media applications from processing VP9 content
• Configure endpoint protection policies to quarantine suspicious video files before user access

# Check VP9 Video Extensions version via PowerShell
Get-AppxPackage -Name "Microsoft.VP9VideoExtensions" | Select-Object Name, Version

# Force update of Microsoft Store apps (requires elevated privileges)
Get-CimInstance -Namespace "root\cimv2\mdm\dmmap" -ClassName "MDM_EnterpriseModernAppManagement_AppManagement01" | Invoke-CimMethod -MethodName "UpdateScanMethod"