CVE-2017-11218 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 in XFA event management. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 08/30/2024
The vulnerability identified as CVE-2017-11218 represents a critical use after free flaw within Adobe Acrobat Reader's XFA event management system. This vulnerability affects multiple versions of Adobe Acrobat Reader including 2017.009.20058 and earlier, 2017.008.30051 and earlier, 2015.006.30306 and earlier, and 11.0.20 and earlier versions. The flaw resides in how the application handles memory management during XFA (XML Forms Architecture) event processing, creating conditions where freed memory blocks can be accessed and manipulated by malicious actors. This type of vulnerability falls under the CWE-416 category of Use After Free, which is classified as a critical memory safety issue in the Common Weakness Enumeration framework. The vulnerability is particularly dangerous because it allows for arbitrary code execution, making it a prime target for attackers seeking to compromise systems through document-based attacks.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious PDF document containing specially crafted XFA elements that trigger the flawed memory management behavior. During normal operation, when XFA events are processed, the application allocates memory for event handlers and subsequently frees this memory upon completion. However, the flaw allows attackers to manipulate the event processing flow in such a way that previously freed memory locations are accessed or overwritten, potentially allowing the execution of arbitrary code. This attack vector leverages the fact that the application does not properly validate the state of memory objects before accessing them, creating a window of opportunity for code injection. The vulnerability demonstrates poor memory management practices and inadequate bounds checking within the XFA event processing subsystem.
The operational impact of CVE-2017-11218 is severe and far-reaching across enterprise environments that rely on Adobe Acrobat Reader for document processing. Organizations using affected versions of the software face significant risk of remote code execution attacks, which could result in complete system compromise, data exfiltration, and persistent backdoor access. The vulnerability is particularly concerning in corporate environments where users frequently open PDF documents from untrusted sources, as the attack can be delivered through simple email attachments or web downloads. This flaw aligns with ATT&CK technique T1203 (Exploitation for Client Execution) and can be used to establish initial access points within networks. The widespread adoption of Adobe Acrobat Reader across various industries means that exploitation of this vulnerability could affect sectors including finance, healthcare, government, and critical infrastructure organizations. Security teams must consider the potential for lateral movement and privilege escalation once initial compromise occurs, as the attacker could leverage the arbitrary code execution capability to gain deeper system access.
Organizations should immediately implement mitigations including prompt patching of Adobe Acrobat Reader to versions that address the use after free vulnerability. The recommended approach involves deploying the latest security updates from Adobe, which typically include memory management fixes and enhanced input validation for XFA elements. System administrators should consider implementing additional security controls such as PDF document sandboxing, restricted file type handling, and network-based protections to reduce the attack surface. Network segmentation and application whitelisting can help limit the potential impact of successful exploitation attempts. The vulnerability also highlights the importance of regular security assessments and vulnerability management programs to identify and remediate similar memory safety issues across the organization's software portfolio. Security monitoring should include detection of suspicious PDF processing activities and anomalous memory access patterns that could indicate exploitation attempts. Organizations should also consider implementing email filtering solutions that can identify and block potentially malicious PDF attachments before they reach end users.