CVE-2018-9977 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 9.0.0.29935. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the parsing of Modifier Chain objects in U3D files. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code under the context of the current process. Was ZDI-CAN-5427.
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Analysis
by VulDB Data Team • 02/06/2020
CVE-2018-9977 represents a critical remote code execution vulnerability affecting Foxit Reader version 9.0.0.29935 and potentially other versions within the same product line. This vulnerability falls under the Common Weakness Enumeration category CWE-476 which specifically addresses NULL pointer dereferences, making it a fundamental flaw in memory management and object validation. The vulnerability exists within the Universal 3D file format parsing component of the PDF reader, specifically in how the software handles Modifier Chain objects. When processing U3D files, the application fails to properly validate whether objects exist before attempting to perform operations on them, creating a dangerous condition where a NULL pointer dereference can occur.
The exploitation mechanism requires user interaction through either visiting a malicious webpage that loads a crafted U3D file or opening a malicious file directly within the application. This makes the vulnerability particularly concerning as it can be delivered through various attack vectors including phishing campaigns, compromised websites, or malicious email attachments. The technical flaw manifests when the parsing engine encounters a Modifier Chain object that has not been properly initialized or validated, leading to a situation where operations are performed on a null reference. This condition allows an attacker to inject and execute arbitrary code with the privileges of the currently running Foxit Reader process, potentially compromising the entire system.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a persistent foothold within the victim's system. The attacker can leverage this privilege escalation to perform actions such as installing malware, modifying system files, stealing sensitive data, or establishing backdoors for continued access. The vulnerability's location within the PDF rendering engine means that successful exploitation can occur even when users are simply browsing the web or opening documents, making it particularly dangerous in enterprise environments where users frequently interact with external content. This aligns with ATT&CK technique T1059.007 which describes the use of scripting languages for code execution, and T1203 which covers exploitation of remote services through web applications.
Organizations should implement immediate mitigations including updating to the latest version of Foxit Reader where the vulnerability has been patched, implementing network-based protections such as web application firewalls to block malicious U3D content, and conducting user education to avoid visiting suspicious websites or opening untrusted files. System administrators should also consider implementing application whitelisting policies that restrict the execution of unauthorized software, particularly in high-risk environments. The vulnerability demonstrates the importance of proper input validation and object lifecycle management in software development, emphasizing that all external inputs should be rigorously validated before processing. Additionally, security teams should monitor for exploitation attempts through network traffic analysis and endpoint detection systems, as the attack pattern typically involves specific patterns of file access and memory manipulation that can be detected by appropriate security tools.