CVE-2016-0934 in Acrobat Reader
Summary
by MITRE
Use-after-free vulnerability in AGM.dll 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 a multiple-layer PDF document, a different vulnerability than CVE-2016-0932, CVE-2016-0937, CVE-2016-0940, and CVE-2016-0941.
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Analysis
by VulDB Data Team • 07/03/2022
The vulnerability identified as CVE-2016-0934 represents a critical use-after-free flaw in Adobe's AGM.dll component that affects multiple versions of Adobe Reader and Acrobat across Windows and macOS platforms. This vulnerability specifically resides within the graphics management functionality of Adobe's document processing stack, where improper memory management allows attackers to manipulate freed memory locations during PDF document parsing operations. The flaw manifests when processing complex, multi-layered PDF documents that trigger specific memory allocation patterns within the AGM.dll module, creating conditions where freed memory blocks can be reused before proper deallocation occurs.
The technical exploitation of this vulnerability occurs through carefully crafted malicious PDF documents that leverage the multi-layered structure to trigger the use-after-free condition in AGM.dll. When Adobe Reader or Acrobat processes such documents, the parser encounters malformed or specially constructed layers that cause the application to free memory resources while still maintaining references to them. Attackers can then manipulate the memory layout to redirect execution flow, potentially allowing arbitrary code execution with the privileges of the compromised application. This vulnerability falls under the CWE-416 category of Use After Free, which is classified as a critical memory safety issue in software security. The exploit requires a sophisticated understanding of Adobe's internal memory management and PDF parsing mechanisms, making it particularly dangerous as it can be delivered through standard document sharing channels.
The operational impact of CVE-2016-0934 extends beyond simple code execution, as successful exploitation can lead to complete system compromise when attackers leverage the elevated privileges of the Adobe application. The vulnerability affects both Adobe Reader and Acrobat products, with specific versions vulnerable including Adobe Reader versions before 11.0.14, and various DC Classic and DC Continuous versions before their respective patch releases. This widespread impact across multiple product lines and versions creates significant risk for organizations relying on Adobe's document processing software. The vulnerability's exploitation can result in persistent backdoor installations, data exfiltration, and lateral movement within network environments, as the compromised Adobe application can be used as a foothold for further attacks. According to ATT&CK framework, this vulnerability maps to T1059.007 for Command and Scripting Interpreter and T1068 for Exploitation for Privilege Escalation, with potential for lateral movement through T1021.002 for Remote Services.
Mitigation strategies for CVE-2016-0934 require immediate patch deployment across all affected Adobe products, as the vulnerability cannot be effectively mitigated through configuration changes alone. Organizations should prioritize updating to the patched versions of Adobe Reader and Acrobat, particularly focusing on the specific version numbers mentioned in the advisory. Network segmentation and application whitelisting can provide additional layers of protection by preventing execution of untrusted PDF documents, though these measures do not address the underlying memory safety issue. Security monitoring should focus on detecting unusual PDF processing activities and potential exploitation attempts, with particular attention to memory access patterns that might indicate use-after-free conditions. The vulnerability demonstrates the importance of maintaining up-to-date software patches and implementing comprehensive vulnerability management programs, as it represents a classic example of how memory safety issues in widely deployed software can create significant security risks. Adobe's patch release for this vulnerability specifically addresses the memory management issues in AGM.dll, requiring users to update to the latest versions to eliminate the risk of exploitation.