CVE-2018-17656 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 9.2.0.9297. 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 handling of the getDisplayItem method of a TimeField. 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 in the context of the current process. Was ZDI-CAN-6506.
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Analysis
by VulDB Data Team • 05/05/2020
CVE-2018-17656 represents a critical remote code execution vulnerability affecting Foxit Reader version 9.2.0.9297, classified under CWE-476 as a null pointer dereference vulnerability. This weakness occurs within the TimeField class's getDisplayItem method where the application fails to validate whether an object reference exists before attempting to perform operations on it. The vulnerability stems from inadequate input validation and object lifecycle management within the PDF rendering engine, creating a scenario where maliciously crafted PDF documents can trigger unauthorized code execution. The flaw specifically manifests when the application processes TimeField objects without proper null checks, allowing attackers to manipulate the object state and subsequently execute arbitrary code with the privileges of the current process. This vulnerability aligns with ATT&CK technique T1203 by enabling remote code execution through malicious file delivery, and T1059 by leveraging the application's scripting capabilities to execute malicious payloads.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with complete control over the affected system. When a user opens a malicious PDF file containing crafted TimeField objects, the application's failure to validate object existence leads to a null pointer dereference that can be exploited to inject and execute malicious code. The vulnerability requires user interaction through visiting a malicious webpage or opening a malicious file, making it particularly dangerous in phishing campaigns or targeted attacks. Attackers can leverage this weakness to install backdoors, steal sensitive data, or establish persistent access to the compromised system. The vulnerability's exploitation path demonstrates poor defensive programming practices and highlights the importance of input validation and object safety checks in security-critical applications. The issue affects not only individual users but also enterprise environments where Foxit Reader is widely deployed for document processing and viewing.
Mitigation strategies for CVE-2018-17656 should encompass multiple layers of defense to protect against exploitation attempts. Organizations should immediately apply patches from Foxit Corporation to address the specific null pointer dereference vulnerability in the TimeField handling logic. Network administrators should implement web filtering solutions to block access to known malicious domains and file repositories that may host exploit payloads. Endpoint protection measures including application whitelisting and sandboxing can help prevent execution of malicious code even if users inadvertently open compromised files. Security monitoring should focus on detecting anomalous PDF processing activities and unusual network connections originating from Foxit Reader processes. System hardening practices such as disabling unnecessary PDF features, implementing least privilege access controls, and maintaining regular security updates form essential components of a comprehensive defense strategy. The vulnerability underscores the importance of following secure coding practices including mandatory object validation, proper error handling, and input sanitization as recommended by industry standards and security frameworks. Organizations should also consider implementing security awareness training to reduce the risk of successful social engineering attacks that leverage this vulnerability.