CVE-2022-24101: Adobe Acrobat DC Use-After-Free Flaw

CVE-2022-24101 Overview

CVE-2022-24101 is a use-after-free vulnerability affecting Adobe Acrobat Reader DC and related Adobe Acrobat products. This memory corruption flaw could lead to the disclosure of sensitive memory contents, potentially allowing an attacker to bypass security mitigations such as Address Space Layout Randomization (ASLR). The vulnerability requires user interaction—specifically, a victim must open a maliciously crafted file for exploitation to occur.

Critical Impact

Successful exploitation could allow attackers to bypass ASLR protections and gain sensitive memory information, potentially facilitating further attacks against the system.

Affected Products

• Adobe Acrobat DC (Continuous) versions 20.001.20085 and earlier
• Adobe Acrobat Reader DC (Continuous) versions 20.005.3031x and earlier
• Adobe Acrobat Reader (Classic) versions 17.012.30205 and earlier
• Adobe Acrobat (Classic) versions on Windows and macOS

Discovery Timeline

• 2022-05-11 - CVE-2022-24101 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-24101

Vulnerability Analysis

This vulnerability is classified as CWE-416: Use After Free. The flaw exists in the memory handling routines of Adobe Acrobat and Acrobat Reader products. When processing certain PDF content, the application fails to properly manage memory resources, allowing a pointer to reference memory that has already been freed. This dangling pointer condition enables an attacker to craft malicious PDF documents that, when opened, can read from deallocated memory regions.

The information disclosure aspect of this vulnerability is particularly significant because it can leak memory contents that reveal the base addresses of loaded modules. With ASLR bypassed, subsequent exploitation of other vulnerabilities becomes significantly easier, as attackers can reliably predict memory layouts.

Root Cause

The root cause stems from improper lifecycle management of memory objects within the PDF processing engine. When specific PDF structures are parsed, the application deallocates memory but retains a reference to that memory location. Subsequent operations that attempt to access this freed memory result in reading arbitrary heap contents, leading to information disclosure.

This type of vulnerability commonly occurs when complex object hierarchies are destroyed out of order or when asynchronous operations complete after their associated memory has been released.

Attack Vector

The attack requires local access and user interaction. An attacker must craft a malicious PDF file containing specially constructed elements designed to trigger the use-after-free condition. The victim must then open this file using a vulnerable version of Adobe Acrobat or Acrobat Reader. The attack scenario typically involves:

1. Attacker creates a malicious PDF document with embedded content designed to trigger the memory corruption
2. The file is delivered to the victim via email, web download, or file sharing
3. When the victim opens the PDF, the application processes the malicious content
4. The use-after-free condition is triggered, leaking sensitive memory information
5. Leaked data (such as module base addresses) can be used to defeat ASLR for subsequent attacks

The vulnerability manifests during PDF document processing when specific object structures are handled. For detailed technical information, refer to the Adobe Security Bulletin APSB22-16.

Detection Methods for CVE-2022-24101

Indicators of Compromise

• Unexpected crashes or abnormal behavior in Adobe Acrobat or Acrobat Reader processes
• Suspicious PDF files received from untrusted sources with unusual embedded JavaScript or malformed structures
• Memory access violations logged in application crash dumps referencing freed heap regions
• Process behavior indicating memory scanning or probing activities following PDF file operations

Detection Strategies

• Deploy endpoint detection rules to identify suspicious PDF file structures commonly associated with use-after-free exploitation attempts
• Monitor for Adobe Acrobat and Reader processes exhibiting abnormal memory access patterns
• Implement file inspection at email gateways and web proxies to detect malicious PDF characteristics
• Use behavioral analysis to detect post-exploitation activities such as attempts to read sensitive memory regions

Monitoring Recommendations

• Enable application crash monitoring for Adobe Acrobat and Reader processes across endpoints
• Implement logging for PDF file access events, particularly from external sources
• Monitor for unusual child process spawning or network activity from PDF reader applications
• Configure SIEM alerts for patterns consistent with exploit delivery via document files

How to Mitigate CVE-2022-24101

Immediate Actions Required

• Update all Adobe Acrobat and Acrobat Reader installations to the latest patched versions immediately
• Enable Protected Mode and Enhanced Security features in Adobe Acrobat Reader settings
• Restrict PDF file downloads from untrusted sources through web filtering policies
• Educate users about the risks of opening PDF files from unknown or suspicious senders

Patch Information

Adobe has released security updates to address this vulnerability as detailed in Security Bulletin APSB22-16. Organizations should update to the following minimum versions:

• Adobe Acrobat DC (Continuous): Update to version 22.001.20085 or later
• Adobe Acrobat Reader DC (Continuous): Update to version 22.001.20085 or later
• Adobe Acrobat 2020 (Classic): Update to version 20.005.30314 or later
• Adobe Acrobat Reader 2020 (Classic): Update to version 20.005.30314 or later
• Adobe Acrobat 2017 (Classic): Update to version 17.012.30227 or later
• Adobe Acrobat Reader 2017 (Classic): Update to version 17.012.30227 or later

Workarounds

• Enable Protected View for all PDF files opened from potentially unsafe locations
• Disable JavaScript execution in Adobe Reader preferences to reduce the attack surface
• Use alternative PDF readers for opening files from untrusted sources as a temporary measure
• Implement application whitelisting to control which applications can open PDF files

# Disable JavaScript in Adobe Reader via registry (Windows)
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\JSPrefs" /v bEnableJS /t REG_DWORD /d 0 /f

# Enable Protected View for all files (Windows Registry)
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\TrustManager" /v bProtectedMode /t REG_DWORD /d 1 /f