CVE-2017-8455 in Foxit
Summary
by MITRE
Foxit Reader before 8.2.1 and PhantomPDF before 8.2.1 have an out-of-bounds read that allows remote attackers to obtain sensitive information or possibly execute arbitrary code via a crafted font in a PDF document.
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Analysis
by VulDB Data Team • 09/23/2020
The vulnerability identified as CVE-2017-8455 represents a critical out-of-bounds read flaw affecting Foxit Reader versions prior to 8.2.1 and PhantomPDF versions before 8.2.1. This vulnerability resides within the PDF rendering engine's handling of font data structures, specifically when processing malformed or crafted font elements embedded within PDF documents. The flaw manifests when the application attempts to read memory locations beyond the allocated buffer boundaries during font parsing operations, creating potential attack vectors for remote exploitation.
The technical implementation of this vulnerability stems from insufficient bounds checking within the font processing routines of these PDF readers. When a malicious PDF document contains specially crafted font data, the application's parser fails to validate the size and structure of font tables before attempting to access them. This lack of input validation creates a condition where an attacker can manipulate font data to trigger memory access violations that may lead to information disclosure or code execution. The vulnerability is classified under CWE-129 as an insufficient validation of length of a buffer, which directly maps to the improper bounds checking behavior observed in the affected software.
From an operational perspective, this vulnerability presents significant risk to organizations relying on these PDF readers for document processing and viewing. Remote attackers can exploit this flaw by simply enticing victims to open a maliciously crafted PDF document containing the specially crafted font data. The attack vector requires no user interaction beyond document opening, making it particularly dangerous in enterprise environments where PDF documents are frequently exchanged. Successful exploitation could result in unauthorized information disclosure, potentially exposing sensitive data stored in memory, or in more severe cases, allow attackers to execute arbitrary code with the privileges of the affected application.
The security implications extend beyond simple information disclosure as this vulnerability could enable attackers to escalate privileges and gain deeper system access. The out-of-bounds read condition creates opportunities for attackers to manipulate memory contents or redirect execution flow through controlled buffer over-reads. This aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where attackers might leverage such vulnerabilities to execute malicious payloads. Organizations using these affected versions should consider the potential for persistent threats, as the vulnerability could be exploited in targeted attacks against specific high-value targets within their networks.
Mitigation strategies for CVE-2017-8455 primarily focus on immediate software updates to versions 8.2.1 or later where the vulnerability has been addressed through proper bounds checking implementations. System administrators should implement comprehensive patch management procedures to ensure all instances of Foxit Reader and PhantomPDF are updated across the enterprise environment. Additional defensive measures include implementing PDF content filtering solutions that can detect and block suspicious font data, deploying network-based intrusion detection systems to monitor for exploitation attempts, and establishing user awareness programs to reduce the likelihood of opening untrusted PDF documents. Organizations should also consider implementing sandboxing techniques for PDF processing to limit the potential impact of successful exploitation attempts, particularly in high-risk environments where the vulnerability could be leveraged for advanced persistent threat operations.