CVE-2018-1173 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 9.0.0.29935. 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 XFA borderColor attribute. 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 under the context of the current process. Was ZDI-CAN-5436.
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Analysis
by VulDB Data Team • 02/06/2020
The vulnerability identified as CVE-2018-1173 represents a critical remote code execution flaw in Foxit Reader version 9.0.0.29935 that demonstrates the classic pattern of improper input validation leading to arbitrary code execution. This vulnerability operates under the Common Weakness Enumeration category CWE-476 which specifically addresses NULL pointer dereferences, though the underlying mechanism involves object validation failures rather than simple null pointer access. The flaw manifests within the XFA (XML Forms Architecture) processing subsystem where the application fails to properly validate object existence before attempting operations on the borderColor attribute. This represents a fundamental failure in defensive programming practices where the application assumes object validity without proper validation checks.
The exploitation of this vulnerability requires user interaction through either visiting a malicious webpage or opening a specially crafted malicious file, making it a prime example of a user-initiated attack vector that aligns with ATT&CK technique T1203 - Exploitation for Client Execution. The attack chain begins when a malicious XFA document is processed, triggering the flawed code path where the borderColor attribute is manipulated without proper object validation. When the application attempts to perform operations on what it believes to be a valid object but which may have been improperly initialized or corrupted, the lack of validation creates a condition where memory corruption can occur. This memory corruption typically manifests as stack or heap corruption that can be leveraged by attackers to inject and execute arbitrary code within the context of the Foxit Reader process, effectively providing attackers with the same privileges as the legitimate user.
The operational impact of this vulnerability extends beyond simple code execution as it fundamentally compromises the security boundary of the application. When an attacker successfully exploits this vulnerability, they gain the ability to execute code with the privileges of the Foxit Reader process, which typically runs with the same user permissions as the victim. This creates a potential escalation path where attackers can access sensitive information, modify documents, or even establish persistent access through the compromised application. The vulnerability's presence in a widely used PDF reader application means that successful exploitation could affect thousands of users across multiple organizations, making it particularly dangerous from a threat intelligence perspective. The fact that this vulnerability was tracked as ZDI-CAN-5436 indicates it was recognized by the Zero Day Initiative as a significant threat requiring immediate attention from software vendors and security professionals.
Organizations should implement multiple layers of defense to mitigate this vulnerability effectively. The primary mitigation strategy involves immediate patching of Foxit Reader installations to versions that address the XFA processing flaw. Additionally, network-based defenses such as web application firewalls and content filtering systems can help prevent access to known malicious XFA documents. Security teams should also consider implementing user education programs to raise awareness about the risks of opening untrusted PDF files from unknown sources. From a monitoring perspective, organizations should deploy behavioral analytics to detect anomalous PDF processing activities that might indicate exploitation attempts. The vulnerability serves as a reminder of the importance of input validation in security-critical applications and the need for robust defensive programming practices that prevent object manipulation attacks. This case also highlights the significance of regularly updating third-party software components and maintaining current threat intelligence to identify and respond to similar vulnerabilities in other applications.