CVE-2017-6883 in Foxit Reader
Summary
by MITRE
The ConvertToPDF plugin in Foxit Reader before 8.2.1 and PhantomPDF before 8.2.1 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. The vulnerability could lead to information disclosure; an attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the current process.
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Analysis
by VulDB Data Team • 09/06/2020
The CVE-2017-6883 vulnerability represents a critical security flaw in Foxit Reader and PhantomPDF software versions prior to 8.2.1 on Windows platforms. This vulnerability specifically affects the ConvertToPDF plugin and manifests when the gflags application is enabled, creating a dangerous attack surface that remote adversaries can exploit to disrupt normal application functionality. The flaw stems from improper input validation within the TIFF image processing pipeline, where the software fails to properly handle malformed or crafted TIFF image data, leading to memory corruption issues that can be leveraged for more severe attacks.
The technical implementation of this vulnerability involves an out-of-bounds read condition that occurs when the ConvertToPDF plugin processes specially crafted TIFF images. This memory access violation results in application crashes and can potentially expose sensitive memory contents to attackers. The vulnerability operates at the kernel level within the application's memory management system, where the software attempts to read data beyond the allocated memory boundaries. According to CWE classification, this represents a CWE-125: Out-of-bounds Read vulnerability, which falls under the broader category of memory safety issues that can lead to unpredictable behavior and security breaches.
The operational impact of this vulnerability extends beyond simple denial of service, as it creates opportunities for information disclosure and potential code execution. When an attacker successfully exploits this flaw, they can cause the application to crash while simultaneously potentially exposing sensitive data from memory locations that were previously accessed. The gflags application, which is typically used for debugging and system monitoring, becomes a vector for exploitation when enabled, as it allows the attacker to manipulate how the application handles memory operations. This vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, as it can be leveraged to execute malicious code within the application context, though it primarily functions as an initial exploitation vector rather than a direct execution mechanism.
The exploitation of this vulnerability requires an attacker to craft a malicious TIFF image file that triggers the out-of-bounds read condition in the ConvertToPDF plugin. Once triggered, the application crashes and potentially reveals memory contents that could contain sensitive information such as application state, user data, or cryptographic keys. The vulnerability's severity increases when combined with other exploitation techniques, as it provides a foothold for attackers to escalate privileges and execute arbitrary code within the application's security context. This makes the vulnerability particularly dangerous in environments where these applications are used to process untrusted documents, as it can be exploited through simple document attachment or web-based delivery methods. Organizations using affected versions of Foxit Reader and PhantomPDF should immediately implement mitigation strategies including software updates, input validation controls, and network segmentation to prevent exploitation of this vulnerability.