CVE-2017-2961 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat Reader versions 15.020.20042 and earlier, 15.006.30244 and earlier, 11.0.18 and earlier have an exploitable use after free vulnerability in the XFA engine, related to validation functionality. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 09/01/2024
The vulnerability identified as CVE-2017-2961 represents a critical use after free flaw within Adobe Acrobat Reader's XFA engine, specifically affecting versions up to and including 15.020.20042, 15.006.30244, and 11.0.18. This vulnerability resides in the validation functionality of the XFA (XML Forms Architecture) processing component, which is responsible for handling interactive forms within pdf documents. The XFA engine processes complex form data and validation rules, making it a prime target for attackers seeking to exploit memory management issues that could lead to arbitrary code execution. This flaw demonstrates the inherent risks associated with complex form processing engines that handle user-supplied data without proper memory bounds checking.
The technical implementation of this vulnerability stems from improper memory management within the XFA validation subsystem where freed memory blocks are accessed after being deallocated. When the XFA engine processes malformed form data, it can cause a situation where a pointer references memory that has already been freed, allowing an attacker to manipulate the program state through carefully crafted malicious pdf documents. This use after free condition creates a predictable memory layout that can be exploited to overwrite critical program data structures or function pointers, ultimately enabling code execution. The vulnerability specifically affects the validation functionality, suggesting that when Acrobat Reader attempts to validate form data, it fails to properly track memory allocation status, leading to potential exploitation through controlled data input.
The operational impact of this vulnerability extends beyond simple arbitrary code execution, as it allows attackers to gain full control over the affected system running Adobe Acrobat Reader. Successful exploitation could enable attackers to execute malicious code with the privileges of the user running the application, potentially leading to complete system compromise. This vulnerability is particularly dangerous in enterprise environments where users frequently open pdf documents from untrusted sources, making it a prime candidate for phishing attacks or supply chain compromises. The widespread adoption of Adobe Acrobat Reader across various industries means that exploitation could affect critical infrastructure and sensitive business operations, with potential for data exfiltration, system persistence, and lateral movement within networks. The vulnerability's presence in multiple version streams indicates a fundamental flaw in the XFA engine's memory management that required immediate attention from both Adobe and security professionals.
Mitigation strategies for CVE-2017-2961 should prioritize immediate patch deployment for all affected Adobe Acrobat Reader versions, as this represents the most effective defense against exploitation. Organizations should implement strict pdf document filtering policies, particularly for documents received from external sources or untrusted parties, and consider deploying sandboxing solutions to isolate pdf processing activities. Network-based security controls such as web application firewalls and content inspection systems should be configured to detect and block malicious pdf files containing known exploit patterns. Additionally, user education regarding the risks of opening pdf documents from unknown sources remains crucial, as social engineering often plays a significant role in successful exploitation attempts. The vulnerability aligns with CWE-416, which specifically addresses use after free conditions, and represents a classic example of how complex processing engines can introduce memory safety issues that enable privilege escalation attacks. Organizations should also consider implementing endpoint detection and response solutions that can identify anomalous behavior patterns associated with exploitation attempts, as this vulnerability may be leveraged as part of broader attack campaigns targeting Adobe Reader users.