CVE-2016-6946 in Acrobat Reader
Summary
by MITRE
Use-after-free vulnerability in Adobe Reader and Acrobat before 11.0.18, Acrobat and Acrobat Reader DC Classic before 15.006.30243, and Acrobat and Acrobat Reader DC Continuous before 15.020.20039 on Windows and OS X allows attackers to execute arbitrary code via unspecified vectors, a different vulnerability than CVE-2016-1089, CVE-2016-1091, CVE-2016-6944, CVE-2016-6945, CVE-2016-6949, CVE-2016-6952, CVE-2016-6953, CVE-2016-6961, CVE-2016-6962, CVE-2016-6963, CVE-2016-6964, CVE-2016-6965, CVE-2016-6967, CVE-2016-6968, CVE-2016-6969, CVE-2016-6971, CVE-2016-6979, CVE-2016-6988, and CVE-2016-6993.
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Analysis
by VulDB Data Team • 09/23/2022
The CVE-2016-6946 vulnerability represents a critical use-after-free flaw affecting Adobe Reader and Acrobat products across multiple versions and operating systems. This vulnerability specifically impacts Adobe Reader versions before 11.0.18, Acrobat and Acrobat Reader DC Classic before 15.006.30243, and Acrobat and Acrobat Reader DC Continuous before 15.020.20039 on both Windows and OS X platforms. The flaw occurs when the application processes certain malformed PDF files, creating conditions where memory that has been freed is still accessed by subsequent operations. This particular vulnerability is distinct from several other related issues including CVE-2016-1089, CVE-2016-1091, and numerous others listed in the description, indicating it operates through a unique exploitation vector.
The technical nature of this use-after-free vulnerability stems from improper memory management within Adobe's PDF processing engine. When parsing specific PDF objects or streams, the application fails to properly validate memory references, allowing attackers to manipulate the memory state before it is properly deallocated. This creates a scenario where freed memory blocks can be reallocated and accessed by malicious code, potentially leading to arbitrary code execution. The vulnerability typically manifests when the application encounters malformed PDF content that triggers unexpected behavior in the memory management routines. The underlying cause aligns with CWE-416, which specifically addresses use-after-free conditions in software implementations, making this a classic example of memory safety issues in complex document processing applications.
The operational impact of CVE-2016-6946 presents significant security risks for organizations relying on Adobe Reader and Acrobat for document handling. Attackers can exploit this vulnerability through crafted PDF files delivered via email phishing campaigns, malicious websites, or compromised documents in shared environments. Once successfully exploited, the vulnerability allows remote code execution with the privileges of the user running the vulnerable application, potentially enabling full system compromise. The attack surface is particularly concerning given Adobe Reader's widespread deployment across enterprise environments and the common practice of opening PDF attachments without proper security screening. This vulnerability can be leveraged for privilege escalation, data exfiltration, and establishment of persistent backdoors within target networks, making it a high-value target for advanced persistent threat actors.
Organizations should implement immediate mitigation strategies to address this vulnerability, beginning with the mandatory update of all affected Adobe Reader and Acrobat installations to their patched versions. The recommended remediation approach includes deploying the latest security patches from Adobe, which address the specific memory management issues within the PDF processing engine. System administrators should also consider implementing additional protective measures such as PDF sandboxing, restricted file type handling, and enhanced email filtering to reduce the likelihood of successful exploitation. From an ATT&CK framework perspective, this vulnerability maps to techniques involving exploitation of software vulnerabilities and privilege escalation, with the potential to enable lateral movement within compromised networks. Organizations should also conduct thorough vulnerability assessments to identify any systems running older versions of Adobe products and establish automated patch management processes to prevent future exposure to similar vulnerabilities. The incident response plan should include procedures for detecting and containing exploitation attempts, as well as monitoring for unusual network activity that might indicate successful compromise through this or related vulnerabilities.