CVE-2018-4894 in Acrobat Reader
Summary
by MITRE
An issue was discovered in Adobe Acrobat Reader 2018.009.20050 and earlier versions, 2017.011.30070 and earlier versions, 2015.006.30394 and earlier versions. This vulnerability occurs as a result of computation that reads data that is past the end of the target buffer; the computation is part of the XPS font processing. A successful attack can lead to sensitive data exposure.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 02/10/2023
This vulnerability in Adobe Acrobat Reader represents a classic buffer over-read condition that occurs during XPS font processing operations. The flaw exists in multiple version ranges including 2018.009.20050 and earlier, 2017.011.30070 and earlier, and 2015.006.30394 and earlier versions. The issue manifests when the application processes XPS (XML Paper Specification) documents containing specially crafted font data that triggers improper boundary calculations during memory access operations. This type of vulnerability falls under CWE-125 which specifically addresses "Out-of-bounds Read" conditions where programs access memory locations beyond the intended buffer boundaries. The vulnerability is particularly concerning because it operates within the font processing pipeline of a widely used document viewer application, making it an attractive target for attackers seeking to exploit the application's handling of rich document formats.
The technical execution of this vulnerability involves a buffer over-read scenario where the application's XPS font processing engine performs calculations that result in reading memory beyond the allocated buffer limits. When processing maliciously constructed XPS documents, the font parser fails to properly validate the boundaries of font data structures, leading to the retrieval of adjacent memory contents. This memory access pattern can potentially expose sensitive information such as cryptographic keys, passwords, session tokens, or other confidential data that may be stored in memory adjacent to the target buffer. The vulnerability's impact is amplified by the fact that Acrobat Reader is frequently used to process documents from untrusted sources, making legitimate user interaction with malicious content highly probable. This aligns with ATT&CK technique T1203 which describes "Exploitation for Client Execution" where adversaries leverage vulnerabilities in software to execute code or extract information.
The operational impact of CVE-2018-4894 extends beyond simple data exposure to potentially enable more sophisticated attacks. An attacker who successfully exploits this vulnerability could gain access to sensitive information stored in the application's memory space, potentially including user credentials, system information, or other confidential data. The vulnerability's presence in multiple major version lines indicates a persistent flaw in the application's font processing logic that was not adequately addressed through the affected release cycles. This particular flaw represents a critical security gap in document processing software that could be exploited through social engineering attacks or by delivering malicious XPS documents through various attack vectors including email attachments, web downloads, or compromised websites. Organizations using affected versions of Adobe Acrobat Reader face significant risk of data leakage and potential system compromise when processing untrusted documents. The vulnerability's exploitation requires minimal user interaction beyond opening a malicious document, making it particularly dangerous in enterprise environments where document processing is common and users may not be security-aware. Remediation efforts should focus on immediate patch deployment for all affected versions, along with network segmentation and content filtering to prevent delivery of potentially malicious XPS documents to vulnerable systems.