CVE-2024-39379: Adobe Acrobat Information Disclosure Flaw

CVE-2024-39379 Overview

CVE-2024-39379 is an out-of-bounds read vulnerability affecting Adobe Acrobat for Edge versions 126.0.2592.81 and earlier. This memory disclosure flaw allows attackers to read sensitive memory beyond the intended buffer boundaries, potentially exposing information that could be leveraged to bypass security mitigations such as Address Space Layout Randomization (ASLR). Successful exploitation requires user interaction—specifically, the victim must open a maliciously crafted file.

Critical Impact

This vulnerability enables attackers to disclose sensitive memory contents, potentially bypassing ASLR and other memory protection mechanisms, which could facilitate further exploitation chains.

Affected Products

• Adobe Acrobat for Microsoft Edge versions 126.0.2592.81 and earlier
• Adobe Acrobat browser extension integrated with Edge

Discovery Timeline

• July 31, 2024 - CVE-2024-39379 published to NVD
• October 16, 2024 - Last updated in NVD database

Technical Details for CVE-2024-39379

Vulnerability Analysis

This vulnerability is classified as CWE-125 (Out-of-Bounds Read), a memory safety issue where the application reads data from a location outside the bounds of the intended buffer. In the context of Adobe Acrobat for Edge, the vulnerability occurs when processing specially crafted input files, allowing the application to access memory regions it should not have access to.

The out-of-bounds read condition enables an attacker to extract sensitive information from the application's memory space. This information disclosure is particularly dangerous because it can reveal memory addresses and layout information that would otherwise be randomized by ASLR. By obtaining this information, attackers can defeat ASLR protections, making subsequent exploitation attempts—such as code execution—significantly more reliable.

Root Cause

The root cause of CVE-2024-39379 lies in improper bounds checking within Adobe Acrobat's file parsing routines when integrated with Microsoft Edge. When the application processes certain malformed input, it fails to properly validate the length or boundaries of data being read, resulting in memory access beyond the allocated buffer. This boundary validation failure allows reads into adjacent memory regions containing potentially sensitive data.

Attack Vector

The attack vector for this vulnerability is local, requiring user interaction. An attacker must convince a victim to open a maliciously crafted file through Adobe Acrobat for Edge. This could be achieved through various social engineering techniques such as phishing emails with malicious PDF attachments, compromised websites hosting weaponized documents, or file-sharing platforms distributing the malicious content.

Once the victim opens the malicious file, the out-of-bounds read is triggered automatically during file parsing. The disclosed memory information can then be exfiltrated or used locally to prepare more sophisticated attacks that leverage the defeated ASLR protections.

Detection Methods for CVE-2024-39379

Indicators of Compromise

• Unexpected memory access violations or crashes in Adobe Acrobat for Edge processes
• Anomalous PDF files with malformed structures or unusual embedded objects targeting buffer parsing routines
• Suspicious outbound network connections from Adobe Acrobat processes following document opening

Detection Strategies

• Monitor for abnormal behavior in Adobe Acrobat for Edge processes, particularly memory access patterns during file parsing operations
• Implement file integrity monitoring to detect and quarantine potentially malicious PDF documents before they reach end users
• Deploy endpoint detection and response (EDR) solutions capable of identifying memory disclosure attack patterns

Monitoring Recommendations

• Enable enhanced logging for Adobe Acrobat and Microsoft Edge browser extension activities
• Configure security information and event management (SIEM) systems to alert on unusual document-related process behaviors
• Monitor for indicators of ASLR bypass attempts or memory information leakage on protected endpoints

How to Mitigate CVE-2024-39379

Immediate Actions Required

• Update Adobe Acrobat for Edge to a version newer than 126.0.2592.81 immediately
• Educate users about the risks of opening untrusted PDF documents and files from unknown sources
• Implement application whitelisting to restrict execution of potentially compromised components
• Review and restrict permissions for Adobe Acrobat browser extensions where possible

Patch Information

Adobe and Microsoft have addressed this vulnerability in versions released after 126.0.2592.81. Administrators should consult the Microsoft Security Response Center advisory for detailed patch information and deployment guidance. Ensure automatic updates are enabled for Microsoft Edge and its extensions to receive security patches promptly.

Workarounds

• Disable or remove the Adobe Acrobat for Edge extension until patching is complete
• Configure PDF files to open in alternative, patched PDF readers rather than the integrated Acrobat extension
• Implement network-level filtering to scan and sanitize PDF documents before delivery to end users
• Enable Protected View or sandboxing features where available to limit the impact of potential exploitation