CVE-2016-4094 in Acrobat Reader
Summary
by MITRE
Adobe Reader and Acrobat before 11.0.16, Acrobat and Acrobat Reader DC Classic before 15.006.30172, and Acrobat and Acrobat Reader DC Continuous before 15.016.20039 on Windows and OS X allow attackers to execute arbitrary code or cause a denial of service (memory corruption) via unspecified vectors, a different vulnerability than CVE-2016-1037, CVE-2016-1063, CVE-2016-1064, CVE-2016-1071, CVE-2016-1072, CVE-2016-1073, CVE-2016-1074, CVE-2016-1076, CVE-2016-1077, CVE-2016-1078, CVE-2016-1080, CVE-2016-1081, CVE-2016-1082, CVE-2016-1083, CVE-2016-1084, CVE-2016-1085, CVE-2016-1086, CVE-2016-1088, CVE-2016-1093, CVE-2016-1095, CVE-2016-1116, CVE-2016-1118, CVE-2016-1119, CVE-2016-1120, CVE-2016-1123, CVE-2016-1124, CVE-2016-1125, CVE-2016-1126, CVE-2016-1127, CVE-2016-1128, CVE-2016-1129, CVE-2016-1130, CVE-2016-4088, CVE-2016-4089, CVE-2016-4090, CVE-2016-4093, CVE-2016-4096, CVE-2016-4097, CVE-2016-4098, CVE-2016-4099, CVE-2016-4100, CVE-2016-4101, CVE-2016-4103, CVE-2016-4104, and CVE-2016-4105.
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Analysis
by VulDB Data Team • 10/23/2024
Adobe Reader and Acrobat products have long been targeted by cyber adversaries due to their widespread use and complex codebases that create numerous potential attack surfaces. This particular vulnerability CVE-2016-4094 represents a critical memory corruption flaw that affects multiple versions of Adobe's document processing software across both Windows and macOS platforms. The vulnerability exists within the parsing mechanisms of PDF documents, specifically in how the software handles certain malformed or specially crafted input data structures. Attackers can exploit this weakness by constructing malicious PDF files that trigger buffer overflows or other memory management errors during document rendering or processing. The memory corruption occurs when the application attempts to allocate or access memory regions beyond their intended boundaries, potentially leading to arbitrary code execution or system crashes. This vulnerability is particularly concerning because it operates at a low level within the application's memory management subsystem, making detection and prevention challenging. The flaw demonstrates the classic characteristics of a heap-based buffer overflow as defined by CWE-121, where insufficient bounds checking allows attackers to overwrite adjacent memory locations. Such vulnerabilities are frequently leveraged in exploit chains targeting the broader attack surface of desktop applications, aligning with techniques documented in the ATT&CK framework under the T1059.1001 category for command and scripting interpreter execution. The memory corruption aspect of this vulnerability directly relates to CWE-787 which describes out-of-bounds writes that can lead to arbitrary code execution. The affected versions span across both legacy and newer Adobe Acrobat DC releases, indicating this represents a persistent issue within the software's architecture that was not adequately addressed in the patch cycles leading up to the reported vulnerability. The unspecified vectors mentioned in the description suggest that the attack could be triggered through various means including embedded JavaScript, malformed image data, or corrupted metadata within PDF files. This broad attack surface makes the vulnerability particularly dangerous as it can be exploited through multiple delivery mechanisms, increasing the probability of successful compromise. The vulnerability's impact extends beyond simple denial of service, as successful exploitation can provide attackers with complete system control, making it a prime target for advanced persistent threat actors. Organizations using these vulnerable versions face significant risk when processing untrusted PDF documents, as the attack surface includes not only direct exploitation but also potential privilege escalation opportunities. The memory corruption vulnerability can be exploited through social engineering campaigns where users unknowingly open malicious PDF attachments, or through targeted attacks on specific user groups with access to sensitive information. This type of vulnerability commonly appears in software with extensive parsing capabilities, where the complexity of handling multiple file formats creates numerous potential entry points for attackers. The lack of specific vector information in the CVE description indicates that multiple exploitation paths exist, requiring comprehensive defensive measures across all potential attack vectors.
The technical exploitation of CVE-2016-4094 requires an understanding of how Adobe Reader processes PDF structures and manages memory allocation for document elements. When a vulnerable application encounters a specially crafted PDF file, the parsing engine attempts to handle malformed data structures that cause memory corruption during rendering operations. This typically manifests as heap corruption where attacker-controlled data overflows into adjacent memory regions, potentially allowing code execution at privilege levels matching the application's runtime environment. The vulnerability's classification as a memory corruption issue places it within the scope of CWE-122 which covers heap-based buffer overflows, and CWE-787 which addresses out-of-bounds writes. These weaknesses are particularly dangerous in applications like Adobe Reader that process untrusted content from the internet or email attachments, making them prime targets for exploitation. The attack vector typically involves crafting a PDF document with specific memory layout properties that when processed by the vulnerable software, cause the application to write beyond allocated memory boundaries. The memory corruption can be triggered during various stages of PDF processing including parsing of object structures, rendering of graphics, or execution of embedded scripts within the document. This vulnerability operates at the intersection of multiple attack techniques defined in the MITRE ATT&CK framework, particularly under T1203 for exploitation for privilege escalation and T1059 for command and scripting interpreter usage. The fact that this vulnerability affects both Windows and macOS platforms indicates a cross-platform exploit capability, making it particularly dangerous for organizations with diverse operating system environments. The memory corruption aspect of the flaw means that attackers can potentially overwrite function pointers, return addresses, or other critical program data structures, enabling complete system compromise. The vulnerability's presence in both legacy Acrobat versions and newer DC releases suggests that Adobe's patch management or code review processes may have missed critical memory safety checks in their PDF parsing libraries. This type of issue commonly occurs when applications fail to implement proper bounds checking or memory allocation validation during the processing of complex file formats. The exploitation process often requires precise control over memory layout and can be enhanced through techniques such as return-oriented programming or other exploit mitigation bypass methods. Organizations should consider the broader implications of this vulnerability beyond simple patching, as it may indicate deeper architectural issues in how Adobe handles untrusted input data.
Mitigation strategies for CVE-2016-4094 must address both immediate defensive measures and long-term architectural improvements in how PDF processing is handled within Adobe applications. The most effective immediate response involves applying the official security patches released by Adobe, which typically include memory safety improvements and enhanced input validation mechanisms. Organizations should implement comprehensive network security controls including email filtering, web proxy restrictions, and sandboxing solutions that prevent vulnerable applications from processing untrusted PDF content. The vulnerability's nature as a memory corruption issue makes traditional antivirus solutions less effective, as the exploit often operates at the application level rather than through network-based signatures. Security professionals should consider implementing application control policies that restrict the execution of vulnerable Adobe Reader versions, particularly in high-risk environments such as financial institutions or government agencies. The ATT&CK framework suggests implementing multiple layers of defense including endpoint detection and response capabilities that can monitor for suspicious memory access patterns or unusual application behavior. Organizations should also consider deploying PDF sandboxing solutions that isolate document processing in restricted environments, preventing successful exploitation even if an attacker manages to deliver a malicious file. The vulnerability's cross-platform nature requires consistent security policies across all operating systems, ensuring that both Windows and macOS users are protected through similar defensive measures. Network-based controls such as web application firewalls or content filtering solutions can help prevent users from accessing potentially malicious PDF files through web browsers or email clients. Regular security assessments should include testing for similar memory corruption vulnerabilities in other document processing applications and ensure that input validation mechanisms are properly implemented. The vulnerability's presence in both legacy and newer Adobe releases indicates that organizations should maintain comprehensive asset inventories to identify all potentially vulnerable systems. Additionally, security teams should consider implementing automated patch management systems that ensure timely application of security updates across all vulnerable endpoints. Training programs for end users should emphasize the importance of avoiding suspicious PDF attachments and reporting potential security incidents. The memory corruption characteristics of this vulnerability also suggest that organizations should implement memory protection mechanisms such as DEP (Data Execution Prevention) and ASLR (Address Space Layout Randomization) to make exploitation more difficult even when vulnerabilities exist. Regular security audits should verify that proper input validation is implemented throughout the application's processing pipeline, particularly in areas handling user-supplied data.