CVE-2024-49535: Adobe Acrobat XXE Vulnerability

CVE-2024-49535 Overview

CVE-2024-49535 is an XML External Entity (XXE) vulnerability affecting Adobe Acrobat and Acrobat Reader products. This improper restriction of XML external entity reference (CWE-611) allows an attacker to craft malicious XML input containing references to external entities, potentially leading to unauthorized read access outside the Acrobat sandbox. The vulnerability requires user interaction, specifically requiring a victim to process a malicious XML document.

Critical Impact

Successful exploitation could allow attackers to read sensitive files outside the Acrobat sandbox environment, potentially exposing confidential system data and user information on both Windows and macOS systems.

Affected Products

• Adobe Acrobat versions 24.005.20307 and earlier (Continuous track)
• Adobe Acrobat Reader DC versions 24.005.20307 and earlier (Continuous track)
• Adobe Acrobat versions 24.001.30213, 24.001.30193 and earlier (Classic track)
• Adobe Acrobat Reader versions 20.005.30730, 20.005.30710 and earlier (Classic track)
• Affected on Microsoft Windows and Apple macOS platforms

Discovery Timeline

• 2024-12-10 - CVE-2024-49535 published to NVD
• 2025-01-23 - Last updated in NVD database

Technical Details for CVE-2024-49535

Vulnerability Analysis

This XXE vulnerability exists in Adobe Acrobat's XML parsing functionality. XML External Entity injection occurs when an application processes XML input containing a reference to an external entity, and the XML parser is configured to process these external entity declarations. In the context of Adobe Acrobat, this flaw enables attackers to bypass the application's sandbox protections and access files that should otherwise be restricted.

The attack requires local access and user interaction—specifically, the victim must open and process a maliciously crafted XML document. When the vulnerable XML parser processes the malicious input, it resolves external entity references, allowing the attacker to exfiltrate data from files outside the sandbox boundaries. The scope of this vulnerability extends beyond the vulnerable component itself, as it can impact the confidentiality of resources managed by other system components.

Root Cause

The root cause is an improper restriction of XML External Entity references in Adobe Acrobat's XML parsing engine. The application fails to properly disable or sanitize external entity declarations in XML documents, allowing attackers to define malicious entity references that point to local system files or internal network resources. This is classified under CWE-611 (Improper Restriction of XML External Entity Reference).

Attack Vector

The attack vector is local, requiring the attacker to deliver a malicious XML document to the victim through social engineering or other delivery mechanisms. The exploitation process involves:

1. An attacker crafts a malicious XML document containing external entity declarations pointing to sensitive files
2. The victim opens the malicious document in a vulnerable version of Adobe Acrobat or Acrobat Reader
3. The XML parser processes the external entity references without proper validation
4. The contents of referenced files are accessed and potentially exfiltrated to the attacker

The vulnerability specifically targets the XML parsing functionality within Acrobat, leveraging the trust relationship between the application and the operating system's file system. While the vulnerability requires user interaction, the attack complexity is low once the malicious document is delivered.

Detection Methods for CVE-2024-49535

Indicators of Compromise

• Unusual file access patterns originating from Adobe Acrobat processes, particularly access to sensitive system files
• PDF or XML documents containing DOCTYPE declarations with ENTITY definitions referencing external resources or local file paths
• Acrobat processes making unexpected network connections or accessing files outside normal document directories
• Log entries showing XML parsing errors related to entity resolution failures

Detection Strategies

• Monitor Adobe Acrobat process activity for suspicious file system access outside typical document directories
• Implement file integrity monitoring on sensitive configuration files and user data directories
• Deploy endpoint detection rules to identify PDF documents with embedded malicious XML entity declarations
• Configure network monitoring to detect data exfiltration attempts from Acrobat processes

Monitoring Recommendations

• Enable detailed logging for Adobe Acrobat applications to capture XML parsing events
• Implement behavioral analysis to detect anomalous file access patterns by PDF reader applications
• Monitor for newly created or modified PDF/XML files with suspicious DOCTYPE declarations
• Configure SentinelOne Singularity Platform to alert on sandbox escape attempts from Acrobat processes

How to Mitigate CVE-2024-49535

Immediate Actions Required

• Update Adobe Acrobat and Acrobat Reader to the latest patched versions immediately
• Enable Protected View in Adobe Acrobat to restrict document functionality until the user explicitly trusts the source
• Educate users about the risks of opening PDF or XML documents from untrusted sources
• Consider temporarily disabling JavaScript and external content in Acrobat preferences until patches are applied

Patch Information

Adobe has released security updates addressing this vulnerability as documented in Adobe Security Advisory APSB24-92. Organizations should update to the latest available versions:

• Continuous track: Update to versions newer than 24.005.20307
• Classic 2024 track: Update to versions newer than 24.001.30213
• Classic 2020 track: Update to versions newer than 20.005.30730

Administrators should prioritize deployment through centralized patch management systems and verify successful installation across all endpoints.

Workarounds

• Enable Protected View for all files by navigating to Edit > Preferences > Security (Enhanced) and selecting "Files from potentially unsafe locations"
• Disable JavaScript in Acrobat Reader via Edit > Preferences > JavaScript to reduce attack surface
• Use the Protected Mode feature (sandbox) which is enabled by default to limit potential damage from exploitation
• Implement email attachment filtering to block or quarantine PDF documents with suspicious XML content

# Windows Registry configuration to enforce Protected View
# Run as Administrator
reg add "HKLM\SOFTWARE\Policies\Adobe\Acrobat Reader\DC\FeatureLockDown" /v bProtectedMode /t REG_DWORD /d 1 /f
reg add "HKLM\SOFTWARE\Policies\Adobe\Acrobat Reader\DC\FeatureLockDown" /v iProtectedView /t REG_DWORD /d 2 /f