CVE-2016-8875 in Foxit
Summary
by MITRE
The ConvertToPDF plugin in Foxit Reader and PhantomPDF before 8.1 on Windows, when the gflags app is enabled, allows remote attackers to cause a denial of service (out-of-bounds read and application crash) via a crafted TIFF image, aka "Data from Faulting Address is used as one or more arguments in a subsequent Function Call starting at ConvertToPDF_x86!CreateFXPDFConvertor."
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Analysis
by VulDB Data Team • 05/21/2019
The vulnerability identified as CVE-2016-8875 represents a critical out-of-bounds read flaw within the ConvertToPDF plugin of Foxit Reader and PhantomPDF versions prior to 8.1 on Windows platforms. This vulnerability specifically manifests when the gflags application debugging tool is enabled, creating a dangerous condition where remote attackers can exploit the software's handling of malformed TIFF image files to trigger system instability. The flaw occurs during the processing of TIFF images through the ConvertToPDF_x86!CreateFXPDFConvertor function, where data retrieved from a faulting address is subsequently used as arguments in subsequent function calls, leading to unpredictable behavior and system crashes.
The technical exploitation of this vulnerability leverages the improper validation of input data within the TIFF image parsing mechanism. When a maliciously crafted TIFF file is processed, the ConvertToPDF plugin fails to properly bounds-check memory accesses, allowing an attacker to read data from memory locations outside the intended buffer boundaries. This out-of-bounds memory access pattern aligns with CWE-125, which describes out-of-bounds read vulnerabilities, and specifically demonstrates how improper input validation can lead to memory corruption. The vulnerability's classification as a denial of service issue stems from the fact that the application crashes upon encountering the malformed input, rendering the software unusable for legitimate users while providing attackers with a reliable means of system disruption.
From an operational perspective, this vulnerability presents significant risk to organizations relying on Foxit Reader and PhantomPDF for document processing, particularly in environments where these applications are used to handle untrusted documents from external sources. The requirement for the gflags app to be enabled creates a specific attack vector that could be exploited in targeted scenarios where an attacker has knowledge of the target system's debugging configuration. The vulnerability's impact extends beyond simple service disruption, as it could potentially be chained with other exploits or used as part of broader attack campaigns targeting document processing applications. The flaw's presence in widely deployed PDF processing software means that successful exploitation could affect numerous enterprise environments, potentially compromising document workflows and user productivity.
The mitigation strategy for this vulnerability requires immediate patching of affected Foxit Reader and PhantomPDF installations to version 8.1 or later, which includes fixes for the memory handling issues in the ConvertToPDF plugin. Organizations should also consider disabling the gflags debugging application on production systems where it is not required for legitimate debugging purposes, as this removes one of the prerequisites for successful exploitation. Network administrators should implement monitoring for suspicious file processing activities and consider deploying sandboxing solutions to isolate document processing operations. Additionally, security teams should review their incident response procedures to ensure proper handling of potential exploitation attempts, as the vulnerability's characteristics make it suitable for both targeted attacks and automated exploitation campaigns. The ATT&CK framework classification for this vulnerability would likely fall under T1203, which covers Exploitation for Client Execution, and potentially T1499, which addresses Network Denial of Service, depending on the specific attack methodology employed by adversaries.