CVE-2018-21241 in PhantomPDF
Summary
by MITRE
An issue was discovered in Foxit PhantomPDF before 8.3.6. It has an untrusted search path that allows a DLL to execute remote code.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/22/2020
The vulnerability identified as CVE-2018-21241 represents a critical security flaw in Foxit PhantomPDF software versions prior to 8.3.6, specifically manifesting as an untrusted search path issue that creates a remote code execution vector. This vulnerability stems from the application's improper handling of dynamic link library (dll) loading mechanisms within its search path configuration, allowing malicious actors to potentially execute arbitrary code on affected systems. The flaw exists in the software's dynamic loading behavior where it fails to properly validate or sanitize the paths from which dll files are loaded, creating an attack surface that adversaries can exploit to gain unauthorized system access.
This vulnerability falls under the category of CWE-427 Uncontrolled Search Path Element, which is a well-documented weakness in software security where applications use search paths that can be manipulated by attackers to load malicious code. The issue directly relates to the software's failure to implement proper input validation and secure coding practices during dll loading operations. When PhantomPDF processes documents, it may inadvertently load a malicious dll file from an attacker-controlled location within the search path, bypassing normal security controls and execution restrictions. The attack typically involves placing a specially crafted dll file in a location that the application will search before legitimate system directories, exploiting the trust placed in the application's search order.
The operational impact of this vulnerability extends beyond simple remote code execution, as it can lead to complete system compromise when exploited successfully. Attackers can leverage this flaw to install backdoors, steal sensitive data, modify system configurations, or escalate privileges within the affected environment. The vulnerability affects organizations using older versions of Foxit PhantomPDF, particularly in enterprise settings where document processing is common, making it a significant concern for security teams managing multiple endpoints. The remote nature of the exploit means that attackers do not require physical access to the target system, allowing them to compromise devices through web-based attacks or malicious documents delivered via email or other network vectors.
Organizations should prioritize immediate patching of all affected Foxit PhantomPDF installations to version 8.3.6 or later, as this release includes the necessary security fixes to address the untrusted search path issue. Additionally, system administrators should implement network segmentation and access controls to limit the potential impact of successful exploitation attempts. Security monitoring should be enhanced to detect unusual dll loading patterns or suspicious file placement activities within system directories. The remediation process should include verification of all installed versions and implementation of automated patch management systems to prevent similar vulnerabilities from being introduced in the future. Organizations should also consider implementing application whitelisting policies and enhanced endpoint protection measures to provide defense-in-depth against similar attack vectors, aligning with security frameworks such as the mitre ATT&CK framework's technique T1059 for command and scripting interpreter execution.