CVE-2018-17633 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 subject property of Annotation objects. 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-6498.
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Analysis
by VulDB Data Team • 05/05/2020
CVE-2018-17633 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 flaw exists within the PDF annotation processing subsystem where the application fails to validate whether an object exists before attempting operations on it, creating a dangerous condition that can be exploited by malicious actors. The vulnerability specifically targets the handling of the subject property within Annotation objects, which serves as the attack vector for remote code execution.
The technical implementation of this vulnerability stems from improper input validation within Foxit Reader's PDF parsing engine. When processing maliciously crafted PDF files containing specially constructed annotation objects, the application attempts to access a null pointer reference without first verifying the object's existence. This fundamental flaw in the software's defensive programming practices allows attackers to manipulate the application's execution flow by controlling the annotation data structure. The vulnerability operates at the kernel level within the PDF rendering process, where annotation objects are processed and rendered, making it particularly dangerous as it can be triggered through normal PDF document interaction.
From an operational perspective, this vulnerability requires user interaction to be exploited, meaning that an attacker must convince a target to visit a malicious webpage hosting a crafted PDF file or open a malicious document. This social engineering requirement does not diminish the severity of the flaw, as it can be effectively delivered through phishing campaigns, compromised websites, or malicious email attachments. The attack surface is extensive given that Foxit Reader is widely deployed across enterprise environments and individual users, making it a prime target for exploitation. Successful exploitation results in code execution within the context of the current process, potentially allowing attackers to gain full control over the affected system, escalate privileges, and establish persistent access.
The impact of CVE-2018-17633 aligns with ATT&CK technique T1203 as it enables adversaries to execute arbitrary code through legitimate system processes, and T1059 for command and scripting interpreter usage. Organizations should implement immediate mitigations including disabling PDF plugin execution in web browsers, implementing strict file access controls, and deploying network intrusion detection systems to monitor for exploitation attempts. Regular security updates and patch management procedures are essential, with the vulnerability being addressed through Foxit Reader version 9.2.1 and later releases. Additionally, security awareness training for end users and implementation of email filtering solutions can significantly reduce the risk of successful exploitation through social engineering vectors. The vulnerability demonstrates the critical importance of input validation and proper error handling in security-sensitive applications, particularly those processing untrusted data such as PDF documents.