CVE-2020-9715: Adobe Acrobat DC Use-After-Free Flaw

CVE-2020-9715 Overview

CVE-2020-9715 is a use-after-free vulnerability affecting Adobe Acrobat and Reader products across multiple versions. This memory corruption flaw allows attackers to execute arbitrary code on affected systems when a user opens a specially crafted PDF document. The vulnerability exists in both the continuous and classic tracks of Adobe Acrobat and Reader on Windows and macOS platforms.

Critical Impact

Successful exploitation of this use-after-free vulnerability enables arbitrary code execution, potentially allowing attackers to take complete control of affected systems with the privileges of the current user.

Affected Products

• Adobe Acrobat DC versions 2020.009.20074 and earlier (Continuous)
• Adobe Acrobat Reader DC versions 2020.009.20074 and earlier (Continuous)
• Adobe Acrobat DC version 2020.001.30002 (Classic 2020)
• Adobe Acrobat Reader DC version 2020.001.30002 (Classic 2020)
• Adobe Acrobat 2017 versions 2017.011.30171 and earlier
• Adobe Acrobat 2015 versions 2015.006.30523 and earlier

Discovery Timeline

• 2020-08-19 - CVE-2020-9715 published to NVD
• 2025-05-05 - Last updated in NVD database

Technical Details for CVE-2020-9715

Vulnerability Analysis

CVE-2020-9715 is a use-after-free (CWE-416) vulnerability in Adobe Acrobat and Reader. Use-after-free vulnerabilities occur when a program continues to use memory after it has been freed, leading to undefined behavior that attackers can leverage for malicious purposes.

In this case, the vulnerability resides in how Adobe Acrobat and Reader handle certain objects during PDF document processing. When specific PDF content triggers the vulnerable code path, the application references memory that has already been deallocated. An attacker can craft a malicious PDF file that manipulates the heap layout to place controlled data in the freed memory region, ultimately redirecting execution flow to attacker-controlled code.

The vulnerability requires user interaction—a victim must open a malicious PDF file—but no additional privileges are needed for exploitation. The local attack vector combined with the potential for complete system compromise makes this vulnerability particularly dangerous in environments where users regularly open PDF documents from untrusted sources.

Root Cause

The root cause is a use-after-free condition where an object is freed but subsequently referenced by the application. This typically occurs due to improper object lifecycle management, where one code path deallocates an object while another code path retains and later uses a dangling reference to that same object. In the context of PDF processing, this can manifest during complex document rendering operations or when handling embedded JavaScript or form elements within PDF files.

Attack Vector

Exploitation of CVE-2020-9715 requires the following attack scenario:

1. Malicious PDF Creation: An attacker crafts a specially designed PDF document containing content that triggers the use-after-free condition
2. Delivery Mechanism: The malicious PDF is delivered to the victim via email attachment, malicious website download, or other distribution channels
3. User Interaction: The victim opens the PDF file using a vulnerable version of Adobe Acrobat or Reader
4. Memory Corruption: The application processes the malicious content, triggering the use-after-free condition
5. Code Execution: The attacker's payload executes with the privileges of the user running the application

The vulnerability affects both Windows and macOS platforms, making it a cross-platform threat. Detailed technical analysis of the vulnerability mechanics is available in the Exodus Intel Analysis and Zero Day Initiative Advisory ZDI-20-991.

Detection Methods for CVE-2020-9715

Indicators of Compromise

• Unexpected crashes or abnormal behavior in Adobe Acrobat or Reader processes
• PDF files with suspicious embedded JavaScript or unusual object structures
• Memory access violations logged in system event logs related to Acrobat.exe or AcroRd32.exe
• Unusual child processes spawned by Adobe Acrobat or Reader applications

Detection Strategies

• Deploy endpoint detection rules to monitor for suspicious memory access patterns in Adobe Reader processes
• Implement file scanning solutions that detect malicious PDF structures targeting use-after-free conditions
• Configure application whitelisting to alert on unexpected process creation from Adobe applications
• Use behavioral analysis to detect exploitation attempts based on anomalous API call sequences

Monitoring Recommendations

• Monitor endpoint logs for crashes and exceptions in Adobe Acrobat and Reader products
• Enable enhanced logging for PDF document processing activities in enterprise environments
• Track version compliance across endpoints to identify systems running vulnerable Adobe software
• Implement network monitoring for suspicious PDF file downloads or email attachments

How to Mitigate CVE-2020-9715

Immediate Actions Required

• Update Adobe Acrobat DC (Continuous) to version 2020.012.20041 or later
• Update Adobe Acrobat Reader DC (Continuous) to version 2020.012.20041 or later
• Update Adobe Acrobat 2020 (Classic) to version 2020.001.30005 or later
• Update Adobe Acrobat 2017 (Classic) to version 2017.011.30175 or later
• Update Adobe Acrobat 2015 (Classic) to version 2015.006.30527 or later

Patch Information

Adobe has released security updates addressing this vulnerability in Adobe Security Bulletin APSB20-48. Organizations should prioritize deploying these patches given the potential for arbitrary code execution. The updates are available for all affected product tracks including Continuous and Classic versions on both Windows and macOS platforms.

Workarounds

• Configure Adobe Acrobat/Reader to disable JavaScript execution via Edit > Preferences > JavaScript and uncheck "Enable Acrobat JavaScript"
• Enable Protected View for all files via Edit > Preferences > Security (Enhanced) and select "Files from potentially unsafe locations"
• Implement document sanitization solutions to remove potentially malicious content from PDF files before user access
• Use alternative PDF readers for untrusted documents until patches can be applied

# Windows Registry configuration to disable JavaScript in Adobe Reader
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\JSPrefs" /v bEnableJS /t REG_DWORD /d 0 /f

# Enable Protected View for all files
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\TrustManager" /v iProtectedView /t REG_DWORD /d 2 /f