CVE-2018-15936 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat and Reader versions 2018.011.20063 and earlier, 2017.011.30102 and earlier, and 2015.006.30452 and earlier have an out-of-bounds write vulnerability. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 05/25/2023
Adobe Acrobat and Reader applications contain a critical out-of-bounds write vulnerability that affects multiple versions across different release cycles. This vulnerability resides in the handling of malformed PDF files and represents a fundamental memory corruption flaw that can be exploited by attackers to execute arbitrary code on affected systems. The vulnerability manifests when the software processes specially crafted PDF documents that contain malformed data structures, leading to memory corruption during parsing operations. The out-of-bounds write condition occurs when the application attempts to write data beyond the allocated memory boundaries, potentially overwriting adjacent memory locations that contain critical program data or control structures. This type of vulnerability falls under the CWE-787 category of out-of-bounds write conditions, which are particularly dangerous because they can be leveraged to overwrite function pointers, return addresses, or other critical execution control data. The impact of this vulnerability extends beyond simple denial of service, as successful exploitation can result in complete system compromise and arbitrary code execution with the privileges of the affected user. Attackers can craft malicious PDF files that, when opened by an affected version of Adobe Acrobat or Reader, trigger the memory corruption and allow for remote code execution. This vulnerability is particularly concerning because PDF documents are widely distributed and frequently opened by users across various environments, making it an attractive target for cybercriminals seeking to exploit user trust in document handling applications. The vulnerability aligns with several techniques described in the MITRE ATT&CK framework under the execution and privilege escalation domains, as it enables initial access through malicious document delivery and can potentially lead to system-level compromise.
The technical exploitation of this vulnerability requires careful crafting of PDF file structures that will cause the application to write beyond intended memory boundaries. When Adobe Reader or Acrobat processes a malformed PDF, the parsing engine encounters unexpected data patterns that cause it to allocate insufficient memory for certain objects or to incorrectly calculate memory offsets. This leads to a situation where the application writes data beyond the allocated buffer space, potentially corrupting critical program execution elements. The vulnerability is particularly dangerous because it can be triggered through simple user interaction such as opening a malicious PDF file, requiring no additional user actions or system privileges. The out-of-bounds write behavior can be exploited to overwrite return addresses on the stack, function pointers, or other memory locations that control program flow. This memory corruption can then be leveraged to redirect execution to attacker-controlled code, effectively allowing remote attackers to execute arbitrary commands on the target system. The vulnerability affects multiple product versions, indicating a persistent flaw in the PDF parsing implementation that has not been adequately addressed across different release cycles, suggesting a fundamental design issue in how the software handles malformed input data.
Organizations and users face significant operational risks from this vulnerability, as it can be exploited through various attack vectors including email attachments, web downloads, and malicious websites. The widespread use of Adobe Reader and Acrobat across enterprise environments makes this vulnerability particularly dangerous, as a single compromised system can serve as a foothold for broader network infiltration. The vulnerability's exploitability is enhanced by the fact that PDF files are commonly encountered in legitimate business contexts, making social engineering attacks more effective as users are less likely to suspect malicious content in documents they expect to open. Security teams must consider this vulnerability as a high-priority threat requiring immediate attention, as it can enable attackers to establish persistent access, exfiltrate sensitive data, or deploy additional malware payloads. The vulnerability's potential for remote code execution means that attackers can perform actions such as installing backdoors, modifying system configurations, or accessing confidential information stored on the compromised system. Organizations should implement immediate mitigation strategies including disabling PDF plugin support in web browsers, implementing strict file validation policies, and ensuring all users have the latest security patches installed. The vulnerability also highlights the importance of maintaining up-to-date software and implementing comprehensive security monitoring to detect potential exploitation attempts. Given the nature of the vulnerability and its potential impact, organizations should treat this as a critical security issue requiring immediate remediation across all affected systems.
The remediation approach for this vulnerability centers on applying official security patches released by Adobe, which address the underlying memory handling issues in the PDF parsing engine. Organizations should prioritize updating all installations of Adobe Acrobat and Reader to versions that contain the necessary fixes, ensuring that all users receive the latest security updates through automated update mechanisms. System administrators should also implement additional protective measures such as sandboxing PDF processing, using restricted user accounts for document handling, and deploying network-based security solutions that can detect and block malicious PDF content. The vulnerability's characteristics make it particularly susceptible to exploitation through automated attack tools, so organizations should also consider implementing web application firewalls and content filtering solutions that can identify and block suspicious PDF file patterns. Regular security assessments and penetration testing should be conducted to verify that the patches have been properly applied and that no other related vulnerabilities exist in the environment. Organizations should also establish incident response procedures specifically designed to handle potential exploitation attempts, including monitoring for suspicious file access patterns and implementing appropriate network segmentation to limit the potential impact of successful attacks. The vulnerability serves as a reminder of the critical importance of maintaining current security practices and the need for continuous vigilance in protecting against emerging threats in document processing applications.