CVE-2018-4889 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 image conversion. A successful attack can lead to sensitive data exposure.
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Analysis
by VulDB Data Team • 07/23/2024
This vulnerability in Adobe Acrobat Reader represents a classic buffer overflow condition that manifests during XPS image conversion processes. The flaw exists in the software's handling of memory boundaries when processing XPS (XML Paper Specification) documents, where the application fails to properly validate buffer limits during data parsing operations. The vulnerability affects multiple versions spanning from 2015 through 2018, indicating a persistent issue in the codebase that was not adequately addressed across different release cycles. This type of vulnerability falls under CWE-125: "Out-of-bounds Read" which is classified as a memory safety error that can lead to information disclosure and potentially more severe consequences depending on the execution context.
The technical implementation of this vulnerability occurs when the XPS conversion engine attempts to read data beyond the allocated buffer boundaries. During the parsing of XPS documents, the application computes memory addresses that reference data locations beyond the intended buffer limits. This miscomputation allows an attacker to manipulate the parsing process in such a way that adjacent memory regions are accessed, potentially exposing sensitive information stored in those locations. The vulnerability is particularly concerning because it operates during document conversion rather than execution, meaning that simply opening or converting an XPS file could trigger the condition. This aligns with ATT&CK technique T1059.007 for Windows Scripting and T1068 for Local Privilege Escalation when combined with other exploitation vectors.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks. While the primary risk is sensitive data exposure, the out-of-bounds read condition could be leveraged to extract memory contents that might include encryption keys, user credentials, or other confidential information. The vulnerability's presence in widely used software versions means that organizations with legacy Acrobat installations face significant risk exposure. Attackers could craft malicious XPS documents that trigger this condition when processed by vulnerable versions of Acrobat Reader, potentially leading to data breaches or system compromise. The vulnerability's exploitation requires minimal privileges and can be executed through social engineering techniques targeting users to open malicious documents, making it particularly dangerous in enterprise environments.
Mitigation strategies for this vulnerability should focus on immediate software updates and operational security measures. Organizations must prioritize updating Adobe Acrobat Reader to versions that address this buffer overflow condition, as Adobe released patches specifically targeting CVE-2018-4889. Network-based defenses should include XPS document filtering and sandboxing mechanisms to prevent automatic processing of untrusted XPS files. System administrators should implement strict access controls and monitor for unusual document processing activities that might indicate exploitation attempts. The vulnerability also highlights the importance of regular security assessments and patch management processes, particularly for widely deployed software packages. Additionally, implementing application whitelisting policies that restrict Acrobat Reader execution to trusted environments can reduce the attack surface for this and similar vulnerabilities.