CVE-2017-2951 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 sub-form functionality. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 10/28/2022
The vulnerability identified as CVE-2017-2951 represents a critical use after free flaw within Adobe Acrobat Reader's XFA engine, specifically affecting multiple version ranges including 15.020.20042 and earlier, 15.006.30244 and earlier, and 11.0.18 and earlier. This vulnerability resides in the XFA (XML Forms Architecture) processing functionality that handles form data submission and validation within PDF documents. The flaw manifests when the application processes sub-form elements within XFA structures, creating conditions where memory previously allocated to objects can be accessed and manipulated after it has been freed, leading to unpredictable behavior and potential code execution.
The technical nature of this vulnerability places it squarely within CWE-416, which describes use after free conditions where program memory is accessed after it has been freed by the application. The XFA engine's handling of sub-form functionality creates a scenario where improper memory management occurs during the processing of complex form structures. When an attacker crafts a malicious PDF document containing specially constructed XFA elements with malformed sub-form data, the application's memory management routines fail to properly track object lifecycles, allowing the attacker to manipulate freed memory locations and potentially execute arbitrary code with the privileges of the user running the vulnerable software.
From an operational perspective, this vulnerability presents a significant risk to enterprise environments where Adobe Acrobat Reader remains widely deployed for document viewing and form processing. The exploitability of this vulnerability means that simply opening a maliciously crafted PDF document could result in remote code execution, making it particularly dangerous in phishing campaigns or targeted attacks. The impact extends beyond individual user compromise to potentially enable attackers to establish persistent access, escalate privileges, or move laterally within networks where the vulnerable software is present. Security teams must consider that this vulnerability can be exploited through social engineering tactics, as users may inadvertently open compromised documents during routine business operations.
Organizations should implement immediate mitigations including prompt patching of Adobe Acrobat Reader to versions that address this vulnerability, typically those released after the vulnerability disclosure. Additionally, network-based protections such as PDF content filtering and sandboxing mechanisms can provide additional layers of defense. The vulnerability's classification as a remote code execution flaw aligns with ATT&CK technique T1203, which covers exploitation of remote services and applications, making it a high-priority target for security operations centers. Implementation of principle of least privilege configurations and user education regarding suspicious document attachments can further reduce the attack surface and potential impact of exploitation attempts.