CVE-2017-3116 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat Reader 2017.009.20058 and earlier, 2017.008.30051 and earlier, 2015.006.30306 and earlier, and 11.0.20 and earlier has an exploitable memory corruption vulnerability in the MakeAccessible plugin when parsing TrueType font data. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 01/08/2021
Adobe Acrobat Reader contains a critical memory corruption vulnerability in the MakeAccessible plugin that specifically affects versions up to and including 2017.009.20058, 2017.008.30051, 2015.006.30306, and 11.0.20. This vulnerability stems from improper handling of TrueType font data during the accessibility processing phase, where the plugin fails to properly validate input parameters before processing font structures. The flaw manifests as a buffer overflow condition that occurs when the plugin attempts to parse malformed or specially crafted TrueType font files that are embedded within pdf documents. When exploited, this vulnerability allows attackers to execute arbitrary code with the privileges of the current user, potentially leading to complete system compromise.
The technical implementation of this vulnerability resides in the MakeAccessible plugin's font parsing routines which lack proper bounds checking and memory allocation validation. According to CWE-121, this represents a classic stack-based buffer overflow condition where attacker-controlled data is copied into a fixed-size buffer without adequate size validation. The vulnerability is particularly dangerous because it can be triggered through normal document opening operations, making it an ideal candidate for social engineering attacks where users unknowingly open malicious pdf files containing crafted font data. The exploit requires minimal user interaction beyond opening the malicious document, as the vulnerability is triggered during the automatic accessibility processing that occurs when Acrobat Reader attempts to make documents accessible to users with disabilities.
From an operational perspective, this vulnerability creates significant risk for enterprise environments where Adobe Acrobat Reader is widely deployed and users frequently open pdf documents from untrusted sources. The attack surface is extensive given that pdf documents are commonly shared through email, web downloads, and file transfer protocols. Attackers can leverage this vulnerability to establish persistent access, escalate privileges, or deploy additional malware payloads. The vulnerability maps to several ATT&CK techniques including T1059 for command and control execution and T1068 for privilege escalation. Organizations running affected versions of Adobe Acrobat Reader face potential data breaches, system compromise, and regulatory compliance violations. The exploitation can occur without requiring specialized tools or deep technical knowledge, making it particularly attractive to threat actors seeking to maximize impact with minimal effort.
Mitigation strategies should prioritize immediate patching of all affected Adobe Acrobat Reader installations to the latest available versions. System administrators should implement strict document access controls and consider deploying sandboxing solutions to isolate pdf processing operations. Network-based protections such as web application firewalls and email filtering systems can help detect and block malicious pdf files containing crafted font data. Additionally, organizations should conduct regular security assessments to identify and remediate similar vulnerabilities in other Adobe products and third-party applications that handle font processing. The vulnerability demonstrates the importance of maintaining up-to-date software and implementing defense-in-depth strategies to protect against zero-day exploits targeting commonly used applications. Regular security awareness training for users can also help reduce the risk of successful exploitation through social engineering attacks that rely on user interaction with malicious documents.