CVE-2018-4956 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat and Reader versions 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 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 • 07/21/2024
Adobe Acrobat and Reader applications contain a critical out-of-bounds read vulnerability that affects multiple versions across different release cycles. This vulnerability stems from insufficient input validation within the document processing engine that handles pdf files. The flaw occurs when the application attempts to read memory locations beyond the allocated buffer boundaries during pdf parsing operations. The vulnerability is classified as CWE-125 Out-of-bounds Read according to the Common Weakness Enumeration framework, which represents a fundamental memory safety issue where the application accesses memory outside the intended boundaries. The affected versions include 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier, indicating this represents a long-standing issue that persisted across multiple major releases.
The technical exploitation of this vulnerability requires an attacker to craft a malicious pdf document that triggers the out-of-bounds read condition during normal document processing. When a user opens such a crafted document, the application's pdf parser encounters malformed data structures that cause it to access memory locations beyond the intended buffer limits. This memory access violation can result in information disclosure as the application may inadvertently expose sensitive data from adjacent memory regions. The vulnerability is particularly dangerous because it can be triggered through simple document opening operations, requiring no special privileges or complex attack vectors. The out-of-bounds read behavior can potentially leak memory contents including cryptographic keys, user credentials, or other sensitive application data that resides in adjacent memory locations.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks within the context of targeted exploitation. According to the MITRE ATT&CK framework, this vulnerability could be leveraged as part of a broader attack chain under techniques such as T1059 Command and Scripting Interpreter or T1106 Network Service Scanning, where the leaked information could aid in further compromise of affected systems. Organizations using Adobe Acrobat and Reader across their enterprise networks face significant risk as this vulnerability can be exploited through social engineering campaigns targeting end users with malicious pdf attachments. The widespread adoption of these applications across both enterprise and consumer environments amplifies the potential impact, as the vulnerability affects users who may not be security-aware and could inadvertently trigger the exploit through legitimate document processing activities.
Mitigation strategies should prioritize immediate patching of affected versions to address the root cause of the out-of-bounds read condition. Organizations should implement strict pdf document filtering policies that prevent execution of potentially malicious documents, particularly those received via email or downloaded from untrusted sources. Security teams should consider deploying application whitelisting solutions that restrict pdf processing to known good applications while monitoring for unusual document processing behavior. Network-based intrusion detection systems can be configured to detect suspicious pdf file characteristics that may indicate exploitation attempts. Additionally, regular security awareness training should emphasize the dangers of opening pdf attachments from unknown sources, as the vulnerability is most effectively exploited through user interaction with malicious documents. The remediation process should include comprehensive vulnerability scanning across all endpoints to identify systems running vulnerable versions, followed by immediate patch deployment and validation of the security updates.