CVE-2018-4887 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 Unicode mapping module that is invoked when processing Enhanced Metafile Format (EMF) data (during 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 exists in Adobe Acrobat Reader versions up to and including 2018.009.20050, 2017.011.30070, and 2015.006.30394, representing a classic buffer over-read condition that falls under CWE-125. The flaw manifests within the Unicode mapping module when processing Enhanced Metafile Format (EMF) data during image conversion operations, creating a scenario where the application attempts to read memory beyond the allocated buffer boundaries. This type of vulnerability is particularly dangerous because it can expose sensitive data from adjacent memory regions, potentially revealing confidential information such as encryption keys, user credentials, or other system data that resides in memory. The vulnerability is categorized as a memory safety issue that directly impacts the application's ability to handle malformed input data properly.
The technical execution of this vulnerability requires an attacker to craft a malicious EMF file that triggers the specific code path involving Unicode mapping during image conversion. When the affected Adobe Acrobat Reader processes such a file, the buffer over-read occurs in the Unicode processing module, causing the application to access memory locations beyond the intended buffer limits. This memory access pattern can be exploited to extract information from the application's memory space, potentially leading to information disclosure that could be leveraged in subsequent attacks. The vulnerability demonstrates a lack of proper bounds checking in the Unicode conversion logic, which is a fundamental security requirement according to industry best practices and security standards.
The operational impact of this vulnerability extends beyond simple information disclosure, as it represents a potential stepping stone for more sophisticated attacks within the context of the ATT&CK framework's credential access and defense evasion tactics. An attacker who successfully exploits this vulnerability could potentially gain access to sensitive data that might be used to compromise user accounts, extract system information, or facilitate further exploitation. The vulnerability is particularly concerning in environments where Adobe Acrobat Reader is frequently used to process untrusted documents, as it could be exploited through social engineering attacks or by distributing malicious documents through various attack vectors. This type of vulnerability affects organizations that rely heavily on document processing and could lead to significant data breaches if exploited.
Organizations should immediately update to the latest versions of Adobe Acrobat Reader to mitigate this vulnerability, as Adobe has released patches addressing the buffer over-read condition. System administrators should implement strict document handling policies that restrict the processing of untrusted EMF files and consider deploying application whitelisting solutions to prevent execution of potentially malicious documents. Network monitoring should be enhanced to detect suspicious document processing activities, and regular security assessments should be conducted to ensure proper patch management. Additionally, users should be trained to avoid opening suspicious documents and to verify the source of all incoming files, particularly those containing embedded graphics or metafile data that could trigger this vulnerability during processing.