CVE-2018-16020 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat and Reader versions 2019.008.20081 and earlier, 2019.008.20080 and earlier, 2019.008.20081 and earlier, 2017.011.30106 and earlier version, 2017.011.30105 and earlier version, 2015.006.30457 and earlier, and 2015.006.30456 and earlier have an out-of-bounds read vulnerability. Successful exploitation could lead to information disclosure.
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Analysis
by VulDB Data Team • 08/04/2024
Adobe Acrobat and Reader applications contain a critical out-of-bounds read vulnerability that affects multiple version ranges including 2019.008.20081 and earlier, 2017.011.30106 and earlier, and 2015.006.30457 and earlier versions. This vulnerability falls under the CWE-129 weakness category, specifically representing an improper input validation issue where the software fails to properly validate array indices or buffer boundaries during processing of maliciously crafted PDF files. The flaw occurs when the application attempts to read memory locations beyond the allocated buffer boundaries, potentially exposing sensitive data from adjacent memory regions. This type of vulnerability is particularly dangerous as it can be exploited through crafted PDF documents that, when opened by an affected version of Adobe Reader or Acrobat, trigger the out-of-bounds read condition. The security implications extend beyond simple information disclosure, as the vulnerability can potentially reveal memory addresses, encryption keys, or other sensitive information that could be leveraged by attackers to further compromise systems. According to ATT&CK framework, this vulnerability aligns with T1059.007 for execution through PDF files and T1566 for initial access via malicious documents. The exploitation scenario typically involves an attacker crafting a malicious PDF file that, when opened by an unpatched user, causes the application to read beyond allocated memory boundaries. This can result in the exposure of stack contents, heap data, or other sensitive information that may reveal system configuration details or application state information. The vulnerability represents a significant risk in enterprise environments where users frequently open PDF documents from untrusted sources, potentially enabling attackers to gather intelligence for more sophisticated attacks. Organizations should prioritize immediate patching of all affected versions, as the vulnerability does not require user interaction beyond opening the malicious document, making it particularly dangerous in targeted attack scenarios.
The technical implementation of this out-of-bounds read vulnerability stems from inadequate bounds checking within the PDF parsing routines of Adobe Reader and Acrobat applications. When processing PDF files, the software does not sufficiently validate the size or range of array indices used during document parsing operations, allowing an attacker to manipulate these values to access memory locations that should remain protected. This issue is particularly concerning because PDF files are commonly used in business environments for sharing documents, making them a prime vector for attack. The vulnerability exists in the core parsing engine responsible for interpreting PDF structures, where array elements are accessed without proper validation of their boundaries. The exploitation process typically involves crafting a PDF document containing maliciously constructed array references that, when processed by the vulnerable software, cause the application to read beyond the intended buffer limits. This can lead to information disclosure of memory contents that may include sensitive data such as application state, memory addresses, or other potentially useful information for advanced exploitation techniques. Security researchers have noted that the vulnerability's impact extends beyond simple data exposure, as the leaked information can provide attackers with insights into memory layout and application behavior, potentially enabling more sophisticated attacks such as heap spraying or return-oriented programming techniques. The vulnerability's classification as a remote code execution risk, while not directly stated, is implied due to the potential for information leakage that could be exploited in combination with other vulnerabilities.
Organizations facing this vulnerability should implement immediate remediation strategies including mandatory patch deployment across all affected systems running Adobe Acrobat or Reader versions prior to the specified releases. The recommended mitigation approach involves updating to the latest versions of Adobe Reader and Acrobat that contain fixes for this out-of-bounds read vulnerability, typically found in versions released after the affected date ranges mentioned in the CVE description. System administrators should also implement additional protective measures such as restricting PDF file execution capabilities, deploying sandboxing solutions for PDF processing, and implementing content filtering systems that can identify and block suspicious PDF files before they reach end users. Network-based security controls should be enhanced to monitor for potential exploitation attempts through PDF-related network traffic patterns. The vulnerability's impact on enterprise security requires comprehensive assessment of all systems that may be exposed to PDF documents from external sources, including web applications, email servers, and file sharing systems. Given the nature of the vulnerability and its potential for information disclosure, organizations should also consider implementing memory protection mechanisms such as data execution prevention and address space layout randomization to mitigate potential exploitation. Security teams should conduct regular vulnerability assessments to ensure all Adobe products are updated and that appropriate access controls are in place to limit exposure to potentially malicious PDF files. The ATT&CK framework suggests implementing defensive measures such as application whitelisting to prevent execution of untrusted PDF files, and monitoring for suspicious file access patterns that may indicate exploitation attempts. Additionally, user education programs should be implemented to raise awareness about the risks of opening PDF files from untrusted sources, as social engineering remains a critical component of successful exploitation of such vulnerabilities.