CVE-2023-44323: Adobe Acrobat for Edge Use After Free Flaw

CVE-2023-44323 Overview

CVE-2023-44323 is a Use After Free vulnerability affecting Adobe Acrobat for Edge version 118.0.2088.46 and earlier versions. This memory corruption flaw allows an unauthenticated attacker to cause an application denial-of-service condition in the context of the current user. Successful exploitation requires user interaction, specifically that a victim must open a malicious file crafted by the attacker.

Critical Impact

This Use After Free vulnerability can be exploited to crash Microsoft Edge Chromium when processing malicious PDF content through Adobe Acrobat integration, resulting in denial of service for end users.

Affected Products

• Microsoft Edge Chromium version 118.0.2088.46 and earlier
• Adobe Acrobat for Edge extension (bundled with affected Edge versions)

Discovery Timeline

• 2023-10-30 - CVE-2023-44323 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-44323

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a type of memory corruption issue that occurs when a program continues to use a pointer after the memory it references has been freed. In the context of Adobe Acrobat for Edge, this flaw manifests during the processing of malformed or specially crafted PDF content.

When a user opens a malicious file, the vulnerability triggers improper memory handling within the Adobe Acrobat component integrated into Microsoft Edge Chromium. The freed memory region may be reallocated for other purposes, and subsequent access attempts using the stale pointer lead to undefined behavior, ultimately causing the application to crash.

The local attack vector requires the attacker to deliver a malicious PDF file to the victim through means such as email attachments, malicious downloads, or compromised websites. User interaction is mandatory, as the victim must actively open the crafted file for the exploit to succeed.

Root Cause

The root cause of CVE-2023-44323 lies in improper memory lifecycle management within the Adobe Acrobat PDF rendering component. Specifically, the vulnerability occurs when memory associated with a PDF object is deallocated while references to that memory still exist. When these dangling pointers are subsequently dereferenced during PDF processing operations, the application attempts to access memory that is no longer valid, leading to a crash condition.

This class of vulnerability typically arises from:

• Complex object hierarchies in PDF documents where reference counting fails
• Asynchronous operations that free resources prematurely
• Error handling paths that don't properly clean up all references

Attack Vector

The attack vector for this vulnerability is local, requiring the attacker to somehow deliver the malicious file to the target system. An attacker could exploit this vulnerability through the following scenarios:

1. Phishing campaigns: Distributing malicious PDF files via email attachments
2. Drive-by downloads: Hosting crafted PDF files on compromised or attacker-controlled websites
3. Social engineering: Convincing users to download and open malicious documents
4. File sharing: Placing malicious PDFs in shared network drives or cloud storage

The vulnerability mechanism involves crafting a PDF document that manipulates internal object references to trigger the use-after-free condition. When the victim opens this document in Microsoft Edge with Adobe Acrobat integration, the malformed content causes memory to be freed while still referenced, resulting in application termination. For detailed technical information, refer to the Microsoft Security Update Guide.

Detection Methods for CVE-2023-44323

Indicators of Compromise

• Unexpected crashes of Microsoft Edge Chromium when opening PDF files
• Application event logs showing access violation errors in msedge.exe or Adobe Acrobat-related DLLs
• Memory dump files generated during PDF rendering operations
• User reports of browser instability specifically when viewing PDF content

Detection Strategies

• Monitor endpoint telemetry for recurring Edge browser crashes with PDF-related stack traces
• Implement file integrity monitoring for known malicious PDF signatures or anomalous PDF structure patterns
• Deploy behavioral analysis to detect suspicious PDF files with unusual object reference patterns
• Utilize endpoint detection and response (EDR) solutions to correlate browser crashes with recently accessed files

Monitoring Recommendations

• Enable crash reporting and logging for Microsoft Edge Chromium across enterprise endpoints
• Configure SentinelOne to alert on application termination events associated with PDF handling
• Implement centralized logging for browser stability events to identify potential exploitation attempts
• Monitor network traffic for downloads of PDF files from suspicious or newly registered domains

How to Mitigate CVE-2023-44323

Immediate Actions Required

• Update Microsoft Edge Chromium to the latest version beyond 118.0.2088.46
• Review and apply all pending security updates for Adobe Acrobat components
• Educate users about the risks of opening PDF files from untrusted sources
• Consider temporarily disabling the Adobe Acrobat for Edge extension until patches are applied

Patch Information

Microsoft has released security updates to address this vulnerability. Organizations should apply the latest Microsoft Edge Chromium updates as soon as possible. The official security advisory and patch information can be found at the Microsoft Security Update Guide.

Administrators should ensure automatic updates are enabled for Microsoft Edge, or deploy updates through enterprise management tools such as Microsoft Endpoint Configuration Manager or Windows Server Update Services (WSUS).

Workarounds

• Configure group policies to disable the Adobe Acrobat PDF viewer extension in Microsoft Edge
• Use an alternative PDF viewer application that is not affected by this vulnerability
• Implement email gateway filtering to block or quarantine PDF attachments from external sources
• Enable Microsoft Defender SmartScreen to help protect against malicious file downloads

# Disable Adobe Acrobat PDF extension via registry (Windows)
# Run in PowerShell as Administrator
reg add "HKLM\SOFTWARE\Policies\Microsoft\Edge\ExtensionInstallBlocklist" /v 1 /t REG_SZ /d "ghbmnnjooekpmoecnnnilnnbdlolhkhi" /f

# Alternatively, configure Edge to use built-in PDF viewer
reg add "HKLM\SOFTWARE\Policies\Microsoft\Edge" /v AlwaysOpenPdfExternally /t REG_DWORD /d 0 /f