CVE-2018-17655 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 moveInstance method of a Form object. 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-6505.
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Analysis
by VulDB Data Team • 05/05/2020
CVE-2018-17655 represents a critical remote code execution vulnerability affecting Foxit Reader version 9.2.0.9297, classified under CWE-476 as "Null Pointer Dereference" and aligning with ATT&CK technique T1203 for Exploitation for Client Execution. This vulnerability stems from insufficient input validation within the Form object's moveInstance method, where the application fails to verify object existence before executing operations on it. The flaw creates a dangerous condition where an attacker can manipulate the application's memory state through crafted PDF content, leading to arbitrary code execution with the privileges of the current process. The vulnerability requires user interaction to exploit, meaning a target must either visit a malicious webpage hosting the exploit or open a malicious PDF file containing the crafted form object. This attack vector aligns with ATT&CK tactic TA0005 (Defense Evasion) and technique T1059.007 (Command and Scripting Interpreter: PowerShell) when considering the typical execution context of such exploits. The root cause lies in the improper object validation mechanism within Foxit Reader's PDF parsing engine, where the moveInstance method does not perform adequate null checks before dereferencing object pointers. This allows attackers to construct malicious PDF documents that trigger the vulnerability during normal document rendering operations, effectively bypassing standard security boundaries. The exploitation process typically involves crafting a PDF with a specially constructed Form object that, when processed by the vulnerable Foxit Reader, causes the application to execute unintended code. The vulnerability's impact extends beyond simple code execution as it can lead to complete system compromise, data exfiltration, and persistent access through the elevated privileges granted by the current process context. Organizations using Foxit Reader should immediately apply patches from the vendor and implement network-based protections such as web application firewalls and PDF content filtering to prevent exploitation attempts. The vulnerability demonstrates the importance of proper input validation and object lifecycle management in PDF processing applications, highlighting how seemingly minor validation gaps can result in severe security consequences. This flaw exemplifies the broader category of memory corruption vulnerabilities that frequently appear in document processing software, making it a prime target for advanced persistent threat actors seeking to establish footholds within enterprise environments. The vulnerability's classification as a remote code execution issue places it within the high-risk category of exploits that can be delivered through email attachments, web downloads, or compromised websites, making it particularly dangerous for widespread deployment. Security professionals should monitor for indicators of compromise related to this vulnerability and ensure that all PDF processing applications undergo regular security assessments to identify similar validation gaps in their codebases. The remediation process involves not only patching the specific vulnerability but also implementing defensive coding practices that emphasize early validation and proper error handling throughout the application's object management routines.