CVE-2018-12767 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat and Reader 2018.011.20040 and earlier, 2017.011.30080 and earlier, and 2015.006.30418 and earlier versions have an Out-of-bounds read vulnerability. Successful exploitation could lead to information disclosure.
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Analysis
by VulDB Data Team • 08/12/2024
Adobe Acrobat and Reader versions prior to 2018.011.20040, 2017.011.30080, and 2015.006.30418 contain a critical out-of-bounds read vulnerability that stems from improper input validation within the document parsing component. This flaw resides in the handling of malformed PDF files and occurs when the application attempts to read memory locations beyond the allocated buffer boundaries. The vulnerability manifests during the processing of specially crafted PDF documents that contain malformed data structures or unexpected byte sequences. When the affected software encounters such malformed input, it fails to properly validate array indices or buffer limits before accessing memory regions, resulting in a read operation that extends beyond the intended data boundaries.
The technical implementation of this vulnerability follows a classic out-of-bounds read pattern classified under CWE-129, which represents improper validation of length of inputs. The flaw typically occurs in the parser responsible for interpreting PDF object structures, particularly when processing embedded or compressed data streams. Attackers can exploit this by crafting malicious PDF files that contain oversized arrays or incorrectly formatted data structures that trigger the vulnerable code path. The memory access pattern in question often involves reading beyond allocated memory segments, potentially exposing sensitive data from adjacent memory locations that may contain stack contents, heap data, or other application information.
The operational impact of this vulnerability extends beyond simple information disclosure, as the out-of-bounds read can potentially expose confidential data such as cryptographic keys, user credentials, or internal application state information. An attacker who successfully exploits this vulnerability could gain access to sensitive information that might be stored in memory adjacent to the vulnerable buffer, including but not limited to session tokens, passwords, or other system data. This information disclosure could serve as a stepping stone for more sophisticated attacks, potentially enabling credential theft, privilege escalation, or further exploitation of the target system. The vulnerability is particularly concerning because PDF files are commonly used in email attachments and web downloads, making this attack vector highly accessible to threat actors.
Security professionals should consider this vulnerability in the context of the attack surface defined by the ATT&CK framework, specifically under the technique of credential access and information gathering. The exploitation of this vulnerability aligns with the pattern of using software vulnerabilities to extract sensitive data from target systems. Organizations should implement immediate mitigations including mandatory software updates to the latest versions of Adobe Acrobat and Reader, deployment of network intrusion detection systems to monitor for suspicious PDF file transfers, and user education regarding the dangers of opening untrusted PDF documents. Additionally, implementing application whitelisting policies and sandboxing mechanisms can help reduce the risk of exploitation even if an attacker manages to deliver a malicious file to a user's system. The vulnerability demonstrates the importance of proper input validation and memory safety practices in document processing applications, highlighting the need for regular security assessments and vulnerability management programs to identify and remediate similar issues before they can be exploited in the wild.