CVE-2018-4892 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 is an instance of a use after free vulnerability in the JBIG2 decoder. The vulnerability is triggered by a crafted PDF file that contains a malformed JBIG2 stream. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 02/10/2023
The vulnerability identified as CVE-2018-4892 represents a critical use after free flaw within Adobe Acrobat Reader's JBIG2 decoder implementation. This security weakness affects multiple versions of Adobe's PDF reader software including 2018.009.20050 and earlier, 2017.011.30070 and earlier, and 2015.006.30394 and earlier releases. The flaw resides in how the software processes JBIG2 image data streams which are commonly used for compressing bi-level images in PDF documents. The vulnerability manifests when a maliciously crafted PDF file contains a malformed JBIG2 stream that triggers improper memory management during the decoding process.
The technical nature of this vulnerability aligns with CWE-416 which defines use after free conditions where memory is accessed after it has been freed, creating opportunities for attackers to manipulate program execution flow. When Adobe Acrobat Reader encounters the malformed JBIG2 stream within the PDF document, the decoder fails to properly manage memory allocation and deallocation sequences. This improper handling allows an attacker to potentially control the memory contents and redirect execution flow to malicious code. The attack vector requires the victim to open a specifically crafted PDF file that contains the malicious JBIG2 stream, making this a client-side exploitation scenario that relies on social engineering for initial compromise.
The operational impact of CVE-2018-4892 extends beyond simple privilege escalation as it provides attackers with a pathway to achieve arbitrary code execution within the context of the user's session. This capability enables adversaries to install malware, steal sensitive data, or establish persistent access to compromised systems. The vulnerability affects a widely used application that processes millions of PDF documents daily, making it particularly attractive to threat actors seeking mass exploitation opportunities. Organizations that rely heavily on PDF document processing, including financial institutions, government agencies, and corporate environments, face significant risk exposure from this vulnerability. The attack scenario typically involves delivering a malicious PDF file through email attachments, web downloads, or compromised websites where users are tricked into opening the document.
Mitigation strategies for CVE-2018-4892 primarily focus on immediate software updates and operational security measures. Adobe released patches addressing this vulnerability in subsequent versions of Acrobat Reader, making it essential for organizations to implement timely security updates across all affected systems. Network administrators should consider implementing PDF content filtering and sandboxing solutions to detect and neutralize potentially malicious documents before they reach end users. Additionally, security awareness training programs should emphasize the importance of verifying document sources and avoiding suspicious email attachments. The vulnerability demonstrates the importance of secure memory management practices in multimedia decoders and highlights the need for comprehensive input validation in image processing components. Organizations should also implement network segmentation and access controls to limit the potential impact of successful exploitation attempts, while maintaining regular vulnerability assessments to identify similar weaknesses in other software components.