CVE-2017-3027 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat Reader versions 11.0.19 and earlier, 15.006.30280 and earlier, 15.023.20070 and earlier have an exploitable use after free vulnerability in the XFA module, related to the choiceList element. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 11/28/2022
The vulnerability identified as CVE-2017-3027 represents a critical use after free flaw within Adobe Acrobat Reader's XFA module, specifically affecting multiple version ranges including 11.0.19 and earlier, 15.006.30280 and earlier, and 15.023.20070 and earlier. This issue resides within the choiceList element processing functionality of the XML Forms Architecture implementation, which is a core component responsible for handling interactive form elements in pdf documents. The flaw manifests when the application improperly handles memory management during the processing of choiceList elements, creating conditions where freed memory blocks can be accessed and reused by malicious code. This particular vulnerability falls under the CWE-416 category of Use After Free, which is classified as a severe memory corruption vulnerability that can enable arbitrary code execution.
The technical exploitation of this vulnerability requires an attacker to craft a malicious pdf document containing specially crafted XFA data with malformed choiceList elements. When a victim opens such a document using an affected version of Adobe Acrobat Reader, the application's XFA parser processes the malicious data and triggers the use after free condition. The memory corruption occurs during the handling of the choiceList element, where the application frees memory associated with a choiceList object but continues to reference that memory location. This allows attackers to potentially overwrite memory contents with malicious payloads, enabling remote code execution capabilities. The vulnerability is particularly dangerous because it operates within the context of the PDF reader application, which typically runs with the privileges of the user who opens the document.
The operational impact of CVE-2017-3027 extends beyond simple remote code execution, as it represents a sophisticated attack vector that can be leveraged for privilege escalation and persistence within targeted environments. Attackers can exploit this vulnerability through social engineering campaigns targeting users who frequently open pdf documents, making it particularly effective in phishing attacks and targeted assaults against organizations. The vulnerability's exploitation is not limited to specific operating systems or user configurations, as it affects multiple versions of Adobe Acrobat Reader across different platforms. The attack surface is broadened by the widespread use of Adobe Reader for document viewing, making this vulnerability particularly attractive to threat actors. According to ATT&CK framework, this vulnerability maps to T1059.007 (Command and Scripting Interpreter: PowerShell) and T1068 (Exploitation for Privilege Escalation) techniques, as successful exploitation can lead to elevated privileges and further system compromise.
Mitigation strategies for CVE-2017-3027 require immediate patching of affected Adobe Acrobat Reader installations, with the vendor releasing security updates that address the memory management issues within the XFA module. Organizations should implement strict pdf document filtering policies, particularly blocking pdf files from untrusted sources and disabling XFA form processing where possible. Network-level protections can include pdf content filtering solutions that scan and validate pdf documents before delivery to end users. System administrators should consider implementing application whitelisting policies that restrict execution of untrusted pdf files, combined with regular security awareness training for users to recognize potentially malicious pdf documents. The vulnerability also highlights the importance of maintaining current security patches for third-party applications and implementing layered security approaches that reduce the attack surface for such memory corruption vulnerabilities. Additional defensive measures include monitoring for unusual network traffic patterns that might indicate exploitation attempts and implementing endpoint detection and response capabilities to identify and contain potential compromises.