CVE-2022-28838: Adobe Acrobat DC Use-After-Free Flaw

CVE-2022-28838 Overview

CVE-2022-28838 is a use-after-free vulnerability affecting Adobe Acrobat and Acrobat Reader products across multiple versions and tracks. This memory corruption flaw could allow an attacker to achieve arbitrary code execution in the context of the current user. Successful exploitation requires user interaction, specifically that a victim must open a malicious PDF file crafted to trigger the vulnerability.

Critical Impact

Successful exploitation enables arbitrary code execution with the privileges of the current user, potentially leading to complete system compromise through malicious PDF documents.

Affected Products

• Adobe Acrobat DC (Continuous Track) version 22.001.2011x and earlier
• Adobe Acrobat Reader DC (Continuous Track) version 22.001.2011x and earlier
• Adobe Acrobat (Classic Track) versions 20.005.3033x and earlier, 17.012.3022x and earlier
• Adobe Acrobat Reader (Classic Track) versions 20.005.3033x and earlier, 17.012.3022x and earlier
• Affected on Microsoft Windows and Apple macOS platforms

Discovery Timeline

• 2022-05-11 - CVE-2022-28838 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-28838

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a type of memory corruption vulnerability that occurs when a program continues to use a pointer after the memory it references has been freed. In the context of Adobe Acrobat products, this flaw exists in the PDF parsing and rendering engine.

When a specially crafted PDF document is processed, the application may improperly manage memory objects, allowing an attacker to manipulate the freed memory region. If successful, this manipulation can redirect program execution to attacker-controlled code, enabling arbitrary code execution within the security context of the user running the vulnerable application.

The local attack vector requires user interaction, meaning a victim must be socially engineered into opening a malicious PDF file. This could occur through email attachments, malicious downloads, or compromised document repositories.

Root Cause

The root cause is improper memory management within Adobe Acrobat's PDF processing functionality. When certain PDF objects are parsed, the application fails to properly track memory allocations and deallocations. A pointer to previously freed memory remains accessible and can be dereferenced, leading to the use-after-free condition.

This type of vulnerability commonly arises when complex data structures with multiple references are not carefully managed throughout their lifecycle. The PDF format's complexity and rich feature set creates numerous opportunities for such memory management errors.

Attack Vector

The attack requires local access and user interaction. An attacker would need to:

1. Craft a malicious PDF document that triggers the use-after-free condition
2. Deliver the malicious PDF to the victim through phishing emails, malicious websites, or file sharing
3. Convince the victim to open the PDF using a vulnerable version of Adobe Acrobat or Acrobat Reader
4. Upon opening, the malicious PDF exploits the memory corruption to execute arbitrary code with the victim's privileges

The vulnerability can be triggered by manipulating specific PDF structures that cause premature deallocation of memory objects while references to those objects remain active in the application.

Detection Methods for CVE-2022-28838

Indicators of Compromise

• Unexpected crashes of Adobe Acrobat or Acrobat Reader processes
• Suspicious child processes spawned from Acrobat.exe or AcroRd32.exe
• PDF files with anomalous or heavily obfuscated embedded content
• Unusual network connections initiated by Adobe Acrobat processes

Detection Strategies

• Monitor for unusual process behavior originating from Adobe Acrobat applications, including unexpected child process creation
• Deploy endpoint detection rules targeting memory corruption exploitation techniques
• Implement PDF sandboxing and analysis for incoming documents via email gateways
• Use application whitelisting to prevent unauthorized code execution from document applications

Monitoring Recommendations

• Enable enhanced logging for Adobe Acrobat application events
• Monitor for Windows Defender or endpoint protection alerts related to exploit prevention
• Track file system activity from Adobe Acrobat processes for suspicious file writes
• Review process creation logs for anomalous behavior patterns following PDF file access

How to Mitigate CVE-2022-28838

Immediate Actions Required

• Update all Adobe Acrobat and Acrobat Reader installations to the latest patched versions immediately
• Enable Protected Mode and Protected View in Adobe Acrobat settings
• Block or quarantine suspicious PDF attachments at email gateways pending analysis
• Educate users about the risks of opening PDF documents from untrusted sources

Patch Information

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

• Acrobat DC (Continuous): Version 22.001.20117 or later
• Acrobat Reader DC (Continuous): Version 22.001.20117 or later
• Acrobat 2020 (Classic): Version 20.005.30334 or later
• Acrobat Reader 2020 (Classic): Version 20.005.30334 or later
• Acrobat 2017 (Classic): Version 17.012.30229 or later
• Acrobat Reader 2017 (Classic): Version 17.012.30229 or later

Workarounds

• Enable Protected Mode in Adobe Acrobat Reader (Edit → Preferences → Security (Enhanced) → Enable Protected Mode at startup)
• Configure Protected View for all files (Edit → Preferences → Security (Enhanced) → Protected View → All files)
• Use browser-based PDF viewers for untrusted documents as an alternative to desktop applications
• Implement application control policies to restrict Adobe Acrobat from executing child processes

# Verify Adobe Acrobat version on Windows (PowerShell)
Get-ItemProperty "HKLM:\SOFTWARE\Adobe\Acrobat Reader\DC\Installer" | Select-Object -Property DisplayVersion

# Enable Protected Mode via registry (Windows)
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\Privileged" /v bProtectedMode /t REG_DWORD /d 1 /f