CVE-2016-0940 in Acrobat Reader
Summary
by MITRE
Use-after-free vulnerability in Adobe Reader and Acrobat before 11.0.14, Acrobat and Acrobat Reader DC Classic before 15.006.30119, and Acrobat and Acrobat Reader DC Continuous before 15.010.20056 on Windows and OS X allows attackers to execute arbitrary code via unspecified vectors, a different vulnerability than CVE-2016-0932, CVE-2016-0934, CVE-2016-0937, and CVE-2016-0941.
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Analysis
by VulDB Data Team • 07/03/2022
The CVE-2016-0940 vulnerability represents a critical use-after-free flaw affecting Adobe Reader and Acrobat products across multiple versions and operating systems. This vulnerability resides within the PDF processing engine of Adobe's document viewer applications, specifically targeting memory management functions that handle dynamic memory allocation and deallocation. The flaw manifests when the application processes malformed PDF files that contain specially crafted objects designed to trigger improper memory handling during the parsing process. The vulnerability is classified under CWE-416 as a use-after-free condition, where a program continues to reference memory after it has been freed, creating opportunities for memory corruption and arbitrary code execution.
The technical exploitation of this vulnerability occurs through the manipulation of PDF objects that cause the application to allocate memory for certain structures, subsequently free that memory, and then attempt to access the freed memory location. Attackers can craft malicious PDF documents that trigger this specific memory management issue during normal document rendering operations. The vulnerability affects both Windows and macOS platforms, making it particularly dangerous as it can be exploited across different operating environments. Unlike similar vulnerabilities such as CVE-2016-0932, CVE-2016-0934, CVE-2016-0937, and CVE-2016-0941, this flaw operates through distinct code paths and exploitation techniques, demonstrating the complexity of PDF processing engine vulnerabilities.
The operational impact of CVE-2016-0940 is severe as it allows remote code execution without requiring user interaction beyond opening a malicious document. This means that simply viewing a crafted PDF file in Adobe Reader or Acrobat can provide attackers with complete system compromise capabilities. The vulnerability can be leveraged in phishing campaigns, malicious email attachments, or compromised websites that deliver malicious PDF content. Security researchers have mapped this vulnerability to ATT&CK technique T1203, which describes the use of malicious documents to execute code on target systems, and T1059, covering command and scripting interpreter usage for execution. The vulnerability's exploitation typically results in privilege escalation opportunities and can lead to full system compromise, making it a high-priority target for threat actors.
Organizations should prioritize immediate patching of all affected Adobe products, including Adobe Reader versions prior to 11.0.14, Acrobat versions before 11.0.14, and Acrobat Reader DC Classic and Continuous versions before their respective patched releases. Additional mitigations include implementing PDF sandboxing features, restricting PDF file access through network policies, and deploying email filtering solutions that can detect and block suspicious PDF attachments. Security teams should also monitor for indicators of compromise related to this vulnerability and implement network-based intrusion detection systems to identify potential exploitation attempts. The vulnerability highlights the importance of regular software updates and the need for organizations to maintain comprehensive patch management processes for all Adobe applications, particularly those handling untrusted document content.