CVE-2018-17634 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 attachIcon 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-6499.
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Analysis
by VulDB Data Team • 05/05/2020
CVE-2018-17634 represents a critical remote code execution vulnerability affecting Foxit Reader version 9.2.0.9297, classified under CWE-476 as "NULL Pointer Dereference" within the annotation processing subsystem. This vulnerability stems from insufficient input validation during the handling of the attachIcon property within Annotation objects, where the software fails to verify object existence before executing operations on it. The flaw creates a dangerous condition where an attacker can manipulate the annotation structure to trigger a null pointer dereference, ultimately leading to arbitrary code execution within the context of the current process. The vulnerability requires user interaction to exploit, making it particularly dangerous as it can be triggered through visiting a malicious webpage or opening a crafted malicious file, aligning with ATT&CK technique T1203 for "Exploitation for Client Execution." The attack vector exploits the PDF parsing engine's insufficient validation mechanisms, specifically targeting the annotation processing pipeline where the attachIcon property is improperly handled. When a vulnerable Foxit Reader instance processes a malicious PDF containing crafted annotation data, the application attempts to access a null object reference during the attachIcon property processing, causing a crash that can be leveraged for code execution. This vulnerability demonstrates a classic improper validation pattern where the application assumes object existence without proper null checks, creating a pathway for privilege escalation and system compromise. The security implications extend beyond simple code execution as the vulnerability allows attackers to potentially gain full control of the affected system, making it a high-severity threat that aligns with the MITRE ATT&CK framework's exploitation categories. The vulnerability's impact is amplified by its remote nature and the widespread use of Foxit Reader, making it a prime target for attackers seeking to compromise endpoints through web-based attacks. Organizations utilizing Foxit Reader should immediately implement mitigations including disabling the problematic annotation processing functionality, updating to patched versions, and implementing network-based controls to block malicious PDF content.
The technical exploitation of this vulnerability follows a predictable pattern where attackers craft malicious PDF documents containing specially formatted annotation objects with invalid attachIcon properties. The lack of proper object validation creates a predictable crash scenario that can be weaponized through Return Oriented Programming (ROP) or other exploitation techniques to execute malicious payloads. The vulnerability's classification as a NULL pointer dereference under CWE-476 indicates that the underlying issue is a fundamental failure in input validation, where the application does not properly check whether objects exist before attempting operations on them. This type of vulnerability is particularly concerning in PDF readers due to the complex parsing requirements and the wide variety of objects that can be embedded within PDF files. The exploitation process requires careful crafting of the malicious PDF to ensure that the annotation processing code path is triggered, typically involving the creation of malformed annotation objects that cause the application to attempt operations on non-existent objects. Attackers can leverage this vulnerability to execute code with the privileges of the Foxit Reader process, potentially leading to complete system compromise and persistent access. The vulnerability's characteristics align with ATT&CK technique T1059 for "Command and Scripting Interpreter" as the execution of arbitrary code allows for command execution within the compromised system. This vulnerability underscores the importance of proper input validation and object lifecycle management in security-critical applications, particularly those handling untrusted input such as PDF documents. The attack surface is broad due to the common usage of PDF readers across various platforms and the ease with which malicious PDFs can be distributed through email, web downloads, or other attack vectors. Security practitioners should monitor for indicators of compromise related to this vulnerability and implement appropriate defensive measures including application whitelisting, sandboxing, and network traffic inspection to prevent exploitation attempts. The vulnerability's remediation requires updating to patched versions of Foxit Reader or implementing compensating controls to prevent the processing of potentially malicious PDF content.
Organizations should prioritize immediate remediation of this vulnerability through official patches provided by Foxit Corporation, as the vulnerability's remote exploitability and code execution capabilities pose significant risks to endpoint security. The vulnerability's impact extends beyond individual system compromise to potential network-wide infiltration, especially in enterprise environments where PDF documents are frequently shared and opened. Security teams should implement comprehensive monitoring to detect exploitation attempts and establish incident response procedures specific to PDF-based attacks. The vulnerability's characteristics make it particularly susceptible to automated exploitation, meaning that organizations without proper defenses may be compromised within minutes of the vulnerability being publicly disclosed. Network segmentation and application control measures can provide additional layers of protection while waiting for official patches. The vulnerability's exploitation requires minimal user interaction, making it particularly dangerous in environments where users may inadvertently encounter malicious PDF content through normal business operations. Regular security awareness training should emphasize the risks of opening unexpected PDF files and visiting untrusted websites that could host malicious content. The vulnerability's presence in widely-used software like Foxit Reader makes it a prime target for nation-state actors and cybercriminals seeking to establish persistent access to target networks. Security professionals should also consider implementing sandboxing solutions for PDF processing to isolate potentially malicious content and prevent successful exploitation attempts. The vulnerability's exploitation demonstrates the critical importance of proper software security practices including input validation, object lifecycle management, and secure coding principles that prevent similar issues from occurring in other applications.