CVE-2018-4902 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 rendering engine. The vulnerability is triggered by a crafted PDF file containing a video annotation (and corresponding media files) that is activated by the embedded JavaScript. 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-2018-4902 represents a critical use after free flaw within Adobe Acrobat Reader's PDF rendering engine, affecting multiple versions including 2018.009.20050 and earlier, 2017.011.30070 and earlier, and 2015.006.30394 and earlier. This issue manifests when processing specially crafted PDF files that contain video annotations accompanied by embedded media files, with the exploitation occurring through embedded javascript code that triggers the vulnerable rendering path. The flaw resides in the improper memory management handling of video annotation objects, where memory allocated for these objects is freed but subsequently accessed by the javascript engine, creating a scenario where attackers can manipulate the freed memory location for malicious purposes.
The technical implementation of this vulnerability follows a classic use after free pattern where the rendering engine allocates memory for video annotation objects during PDF processing, but fails to properly validate or manage the lifecycle of these objects. When javascript code within the PDF file activates the video annotation, the system attempts to access memory that has already been freed, allowing for memory corruption that can be leveraged by attackers to execute arbitrary code. This vulnerability aligns with CWE-416 which specifically addresses use after free conditions, and demonstrates how improper memory management in complex multimedia rendering components can create exploitable conditions. The attack vector requires the victim to open a malicious PDF file containing the crafted video annotation and javascript payload, making this a typical social engineering target for phishing campaigns.
The operational impact of CVE-2018-4902 extends beyond simple privilege escalation as it provides attackers with a complete code execution capability within the context of the Acrobat Reader application. This vulnerability can be exploited in targeted attacks where adversaries craft PDF documents designed to exploit the specific memory corruption pattern, potentially leading to full system compromise when Acrobat Reader is used to process these documents. The vulnerability's exploitation is particularly concerning due to Acrobat Reader's widespread deployment across enterprise environments and individual users, creating a broad attack surface that can be leveraged for data exfiltration, lateral movement, or establishment of persistent access. The flaw can be weaponized as part of advanced persistent threat campaigns where attackers use the vulnerability to establish footholds in target networks, making it a significant concern for organizations that process untrusted PDF documents.
Organizations should implement immediate mitigations including prompt patching of affected Adobe Acrobat Reader versions to address the underlying memory management issues in the PDF rendering engine. System administrators should consider implementing PDF processing controls and sandboxing mechanisms to limit the potential impact of exploitation attempts, while also deploying email filtering solutions to block malicious PDF attachments. Network security controls such as web application firewalls and content inspection systems should be configured to identify and block suspicious PDF files containing known malicious javascript patterns. The vulnerability's classification under the ATT&CK framework for technique T1204.002 (User Execution: Malicious File) emphasizes the importance of user awareness training and email security controls. Additionally, organizations should consider implementing least privilege access controls and monitoring for suspicious Acrobat Reader process behavior, as exploitation of this vulnerability typically involves memory corruption patterns that could be detected through behavioral analysis of the application's execution. Regular security assessments and vulnerability scanning should include verification of Acrobat Reader installations to ensure all systems are patched against this specific use after free vulnerability.