CVE-2024-39383: Adobe Acrobat RCE Vulnerability

CVE-2024-39383 Overview

CVE-2024-39383 is a Use After Free vulnerability affecting Adobe Acrobat Reader that could allow an attacker to execute arbitrary code in the context of the current user. This memory corruption flaw occurs when the application attempts to access memory that has already been freed, creating an exploitable condition. Successful exploitation requires user interaction—specifically, the victim must open a malicious PDF file crafted to trigger the vulnerability.

Critical Impact

Arbitrary code execution in the context of the current user, potentially allowing attackers to install programs, view/change/delete data, or create new accounts with full user rights.

Affected Products

• Adobe Acrobat (Classic track) version 20.005.30636 and earlier
• Adobe Acrobat DC (Continuous track) version 24.002.20965 and earlier
• Adobe Acrobat Reader (Classic track) version 24.001.30123 and earlier
• Adobe Acrobat Reader DC (Continuous track) version 24.002.20964 and earlier
• Affected on Microsoft Windows and Apple macOS platforms

Discovery Timeline

• 2024-08-14 - CVE-2024-39383 published to NVD
• 2024-08-20 - Last updated in NVD database

Technical Details for CVE-2024-39383

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a 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 Reader, this flaw exists in the PDF parsing and rendering engine. When a specially crafted PDF document triggers the vulnerable code path, the application may attempt to reference memory that has been deallocated, leading to undefined behavior that an attacker can exploit for code execution.

The local attack vector means that an attacker cannot remotely exploit this vulnerability without some form of user interaction. The attack complexity is low, indicating that once a user opens a malicious document, exploitation is straightforward without requiring special conditions or sophisticated techniques. No prior privileges are required to craft and deliver the malicious file, though user interaction is mandatory for successful exploitation.

Root Cause

The root cause of CVE-2024-39383 lies in improper memory management within Adobe Acrobat Reader's document processing functionality. The vulnerability occurs when a memory object is freed during document processing, but a reference (dangling pointer) to that freed memory remains in use. When the application subsequently attempts to access this freed memory—potentially to read data or call a function pointer—the attacker can manipulate the contents of that memory region to redirect execution flow to attacker-controlled code.

Use After Free vulnerabilities in document readers like Adobe Acrobat are particularly dangerous because they can be triggered simply by viewing a document, and the ubiquity of PDF files makes social engineering attacks highly effective.

Attack Vector

The attack vector for CVE-2024-39383 requires local access through user interaction. An attacker would typically:

1. Craft a malicious PDF document designed to trigger the Use After Free condition
2. Deliver the document to the victim through email attachments, file sharing, or malicious websites
3. Convince the victim to open the PDF document with an affected version of Adobe Acrobat Reader
4. Upon opening, the malicious document triggers the memory corruption, allowing the attacker to execute arbitrary code with the privileges of the current user

The exploitation mechanism involves heap manipulation techniques where an attacker carefully controls memory allocation patterns to ensure that the freed memory is reallocated with attacker-controlled data before the dangling pointer is dereferenced. This allows the attacker to hijack program execution flow and run arbitrary shellcode.

Detection Methods for CVE-2024-39383

Indicators of Compromise

• Unexpected crashes or abnormal termination of Adobe Acrobat or Acrobat Reader processes
• Suspicious child processes spawned by AcroRd32.exe or Acrobat.exe
• PDF files with unusual JavaScript content or embedded objects attempting memory manipulation
• Post-exploitation indicators such as unexpected network connections from Adobe Reader processes

Detection Strategies

• Monitor for unusual process behavior from Adobe Acrobat Reader, including unexpected child process creation
• Implement endpoint detection rules to identify PDF files with obfuscated JavaScript or suspicious stream objects
• Deploy memory protection technologies that can detect Use After Free exploitation attempts
• Utilize SentinelOne's behavioral AI engine to detect code execution anomalies originating from document readers

Monitoring Recommendations

• Enable logging for PDF document opening events across endpoints
• Monitor for heap spray patterns and unusual memory allocation sequences in Adobe Reader processes
• Implement file integrity monitoring for Adobe Acrobat installation directories
• Track network connections initiated by Adobe Reader processes for post-exploitation activity

How to Mitigate CVE-2024-39383

Immediate Actions Required

• Update all Adobe Acrobat and Acrobat Reader installations to the latest patched versions immediately
• Enable Protected Mode in Adobe Acrobat Reader to sandbox document processing
• Disable JavaScript in Adobe Reader via Edit > Preferences > JavaScript > uncheck "Enable Acrobat JavaScript"
• Block PDF attachments from untrusted sources at the email gateway level
• Educate users about the risks of opening PDF files from unknown senders

Patch Information

Adobe has released security updates to address this vulnerability as documented in security bulletin APSB24-57. Organizations should apply the following updates:

• Adobe Acrobat DC (Continuous): Update to version 24.002.20991 or later
• Adobe Acrobat Reader DC (Continuous): Update to version 24.002.20991 or later
• Adobe Acrobat 2020 (Classic): Update to version 20.005.30655 or later
• Adobe Acrobat Reader 2020 (Classic): Update to version 20.005.30655 or later

For complete version information and download links, refer to the Adobe Acrobat Security Advisory.

Workarounds

• Enable Protected View for all files (Edit > Preferences > Security (Enhanced) > Protected View: All files)
• Configure Adobe Reader to open PDF files in a sandboxed environment
• Use alternative PDF readers temporarily if immediate patching is not possible
• Implement application control policies to restrict Adobe Reader's ability to execute child processes

# 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)
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\TrustManager" /v iProtectedView /t REG_DWORD /d 2 /f