CVE-2018-9952 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 9.0.1.1049. 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 XFA Button elements. When setting the formattedValue attribute, the process does not properly validate 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-5527.
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Analysis
by VulDB Data Team • 02/06/2020
The vulnerability identified as CVE-2018-9952 represents a critical remote code execution flaw affecting Foxit Reader version 9.0.1.1049, demonstrating a classic use-after-free or null pointer dereference condition within the XFA (XML Forms Architecture) button element processing mechanism. This vulnerability operates under the CWE-476 principle of NULL Pointer Dereference, where the application fails to validate object existence before executing operations on it. The flaw specifically manifests when the formattedValue attribute of XFA button elements is manipulated, creating a scenario where an attacker can control memory operations through crafted malicious content.
The exploitation of this vulnerability requires user interaction, making it a client-side attack vector that relies on social engineering to deliver malicious payloads. Attackers can construct malicious PDF documents containing specially crafted XFA button elements that, when processed by the vulnerable Foxit Reader, trigger the improper object validation. The attack chain begins with a user visiting a malicious webpage hosting the compromised PDF or opening a crafted document, which then executes the malicious code within the context of the current process. This privilege escalation scenario poses significant risk as it allows attackers to execute arbitrary commands with the same privileges as the Foxit Reader application, potentially leading to full system compromise.
From an operational impact perspective, this vulnerability creates a substantial security risk for organizations relying on Foxit Reader for document processing, as it enables remote attackers to gain unauthorized access to systems through seemingly legitimate document interactions. The vulnerability's classification under the ATT&CK framework aligns with T1203 - Exploitation for Client Execution, where attackers leverage application vulnerabilities to execute code on target systems. The attack surface expands significantly since PDF documents are commonly shared across organizations and frequently opened without security scrutiny, making this vector particularly dangerous in enterprise environments.
The technical nature of this flaw demonstrates poor input validation and memory management practices within the XFA processing subsystem of Foxit Reader, where the application fails to implement proper object existence checks before performing operations. This type of vulnerability commonly arises from insufficient bounds checking and improper error handling in complex document parsing libraries. Organizations should implement immediate mitigations including disabling XFA form processing, updating to patched versions of Foxit Reader, and deploying network-based intrusion detection systems to monitor for exploitation attempts. The vulnerability also highlights the importance of sandboxing PDF processing applications and implementing strict content filtering measures to prevent the execution of potentially malicious embedded scripts within document elements.