CVE-2018-9935 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 8.3.2.25013. 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 addField method. 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-5312.
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Analysis
by VulDB Data Team • 02/06/2020
CVE-2018-9935 represents a critical buffer overflow vulnerability affecting Foxit Reader version 8.3.2.25013 that enables remote code execution through improper input validation within the addField method. This vulnerability operates under the Common Weakness Enumeration category CWE-125, which identifies out-of-bounds read conditions where an application accesses memory beyond the boundaries of a valid buffer. The flaw specifically manifests when the software fails to validate whether an object exists before performing operations on it, creating a dangerous condition where attacker-controlled data can trigger unintended memory access patterns.
The exploitation mechanism requires user interaction through either visiting a malicious webpage or opening a specially crafted malicious file, making this a classic example of a client-side attack vector that aligns with ATT&CK technique T1203 - Exploitation for Client Execution. When a victim interacts with the malicious content, the addField method processes the malformed input without proper validation checks, allowing an attacker to manipulate memory structures and execute arbitrary code within the context of the current process. This privilege escalation occurs because the application operates with the same permissions as the user running Foxit Reader, potentially enabling full system compromise if the user has elevated privileges.
The operational impact of this vulnerability extends beyond simple code execution, as it can be leveraged for persistent access and data exfiltration within compromised systems. Attackers can craft malicious PDF documents that, when opened by an unpatched Foxit Reader, provide them with a foothold for further exploitation. The vulnerability's classification as a remote code execution flaw means that attackers do not require physical access to the target system, making it particularly dangerous for enterprise environments where users may encounter malicious content through email attachments or web browsing. Organizations running vulnerable versions of Foxit Reader face significant risk of unauthorized access, data breaches, and potential lateral movement within their networks.
Mitigation strategies should focus on immediate patch deployment as the primary defense mechanism, with organizations prioritizing the update to Foxit Reader version 8.3.3.25014 or later which contains the necessary fixes for this vulnerability. Network-based defenses such as web application firewalls and content filtering systems can provide additional protection by blocking malicious PDF content, though these measures are not foolproof given the sophisticated nature of modern phishing campaigns. Security teams should also implement user education programs to reduce the likelihood of successful exploitation through social engineering attacks, while monitoring for suspicious PDF file downloads or web navigation patterns. The vulnerability's characteristics make it particularly suitable for targeted attacks, so organizations should consider implementing endpoint detection and response solutions that can identify anomalous behavior patterns associated with exploit attempts. Additionally, maintaining up-to-date threat intelligence feeds and vulnerability scanning tools will help identify systems that may have been missed during initial patching efforts, ensuring comprehensive protection across all endpoints.