CVE-2018-1179 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to disclose sensitive information 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 parsing of DataSubBlock structures in GIF images. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated data structure. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the current process. Was ZDI-CAN-5490.
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Analysis
by VulDB Data Team • 02/06/2020
The vulnerability identified as CVE-2018-1179 represents a critical information disclosure flaw affecting Foxit Reader version 9.0.0.29935 and potentially other versions within the same product line. This vulnerability operates under the purview of CWE-125, which specifically addresses out-of-bounds read conditions that occur when a program attempts to access memory beyond the boundaries of a valid data structure. The flaw manifests during the processing of GIF image files, particularly within the DataSubBlock parsing mechanism that is integral to the GIF file format specification. The vulnerability's exploitation requires user interaction, meaning that an attacker must convince a target to visit a malicious webpage or open a specially crafted malicious file containing the vulnerable GIF image structure. This requirement places the vulnerability within the realm of social engineering attacks, where user behavior becomes a critical factor in successful exploitation.
The technical root cause of this vulnerability lies in insufficient input validation mechanisms within the Foxit Reader application's GIF parser implementation. When processing DataSubBlock structures within GIF images, the application fails to properly validate the boundaries of user-supplied data before attempting to read from memory locations. This lack of proper boundary checking creates an out-of-bounds memory read condition where the application attempts to access memory beyond the allocated buffer space for the DataSubBlock structure. The vulnerability's classification as a read past the end of an allocated data structure directly aligns with the Common Weakness Enumeration standard, specifically CWE-125, which describes situations where programs read data past the end of valid buffer boundaries. The memory access violation occurs during the normal parsing flow of GIF image data, making it particularly insidious as it can be triggered by routine document processing activities.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates potential pathways for more severe exploitation techniques. While the primary effect is the disclosure of sensitive memory contents that may include stack contents, application data, or even credentials stored in memory, the vulnerability's potential for code execution cannot be dismissed. Attackers can leverage this information disclosure as a stepping stone to more sophisticated attacks, potentially combining it with other vulnerabilities to achieve arbitrary code execution within the context of the Foxit Reader process. This capability places the vulnerability in the ATT&CK framework under the technique of "Exploitation for Client Execution" where attackers can leverage software vulnerabilities to execute malicious code on target systems. The attack surface is particularly concerning given that Foxit Reader is widely used for document viewing, making it a common target for attackers seeking to compromise user systems through document-based attacks.
Mitigation strategies for CVE-2018-1179 should prioritize immediate patch deployment from Foxit Corporation, as the vendor has acknowledged this vulnerability and provided security updates to address the issue. Organizations should implement strict file validation policies that restrict the types of files users can open within the application, particularly focusing on image file formats that may be processed by the vulnerable parser. Network-based mitigations could include filtering of potentially malicious GIF files at perimeter defenses, though this approach has limitations given that the vulnerability can be triggered through web-based content. System administrators should consider implementing application whitelisting policies that restrict execution of untrusted PDF and image files, while also monitoring for unusual memory access patterns that might indicate exploitation attempts. The vulnerability's nature as a buffer over-read condition makes it particularly susceptible to exploitation through techniques such as heap spraying or information leakage attacks that could reveal memory layout details and facilitate more advanced exploitation methods. Security monitoring should focus on detecting anomalous behavior during document processing, particularly around GIF image parsing operations, and implementing proper input sanitization measures that validate all user-supplied data before processing.