CVE-2017-11256 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 use after free vulnerability when generating content using XFA layout engine. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 08/31/2024
Adobe Acrobat Reader contains a critical use after free vulnerability in its XFA layout engine that affects multiple versions including 2017.009.20058 and earlier, 2017.008.30051 and earlier, 2015.006.30306 and earlier, and 11.0.20 and earlier. This vulnerability falls under CWE-416 which specifically addresses use after free conditions where memory is accessed after it has been freed, creating opportunities for attackers to manipulate program execution flow. The flaw occurs during content generation processes within the XFA (XML Forms Architecture) layout engine, which is responsible for rendering dynamic forms and complex document layouts. When processing maliciously crafted XFA content, the application fails to properly manage memory allocation and deallocation sequences, leading to a situation where freed memory blocks are subsequently accessed by the application, potentially allowing attackers to execute arbitrary code with the privileges of the user running the application.
The operational impact of this vulnerability extends beyond simple code execution, as it represents a significant escalation vector within the attack chain. According to ATT&CK framework, this vulnerability maps to T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation. The vulnerability can be exploited through crafted PDF files containing malicious XFA content that, when opened in the affected versions of Adobe Acrobat Reader, triggers the use after free condition. This creates an ideal environment for attackers to execute shellcode or malware payloads directly within the context of the user's session, potentially leading to full system compromise. The attack surface is particularly concerning given that Adobe Acrobat Reader is widely deployed across enterprise environments and individual users, making it a prime target for social engineering campaigns where users might inadvertently open malicious PDF documents.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected versions, as Adobe released security updates to address the memory management issues in their XFA engine. Organizations should implement strict document filtering policies to prevent the opening of untrusted PDF files, particularly those containing XFA forms. Network-based protections such as sandboxing PDF processing and implementing content inspection systems can provide additional layers of defense. The vulnerability also highlights the importance of keeping all document processing software up to date and following secure coding practices that prevent use after free conditions. Security teams should monitor for exploitation attempts through network traffic analysis and endpoint detection systems, as the exploitation typically involves specific memory access patterns that can be detected by advanced threat hunting techniques. Regular security assessments of document handling processes and user education regarding suspicious PDF attachments remain essential defensive measures against this class of vulnerability.