CVE-2009-0191 in Foxit
Summary
by MITRE
Foxit Reader 2.3 before Build 3902 and 3.0 before Build 1506, including 3.0.2009.1301, does not properly handle a JBIG2 symbol dictionary segment with zero new symbols, which allows remote attackers to execute arbitrary code via a crafted PDF file that triggers a dereference of an uninitialized memory location.
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Analysis
by VulDB Data Team • 03/17/2021
The vulnerability identified as CVE-2009-0191 represents a critical memory safety issue affecting Foxit Reader versions 2.3 through 3.0. This flaw resides in the PDF parsing engine's handling of JBIG2 compression data, specifically within the symbol dictionary segment processing functionality. The vulnerability stems from improper validation of JBIG2 data structures, creating a scenario where uninitialized memory locations are accessed during PDF document rendering. The affected versions include Foxit Reader 2.3 prior to Build 3902 and version 3.0 prior to Build 1506, with the specific build 3.0.2009.1301 also being vulnerable. This represents a classic buffer over-read condition that can be exploited through maliciously crafted PDF documents.
The technical implementation of this vulnerability involves the JBIG2 decoding process where the software fails to properly validate the symbol dictionary segment when it contains zero new symbols. When a PDF document contains such malformed JBIG2 data, the Foxit Reader engine attempts to access memory locations that have not been properly initialized, leading to unpredictable behavior. This uninitialized memory access creates a potential code execution vector because the program may jump to arbitrary memory locations or corrupt memory structures that could be manipulated by attackers. The flaw specifically manifests during the PDF rendering process when the application attempts to parse and decompress JBIG2 compressed image data, making it particularly dangerous as it can be triggered simply by opening a malicious document.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a remote code execution capability that can be leveraged without user interaction. An attacker could craft a PDF document containing the malformed JBIG2 symbol dictionary segment and deliver it via email, web download, or other means. When a victim opens the document in an affected Foxit Reader version, the uninitialized memory dereference would trigger the exploit, potentially allowing the attacker to execute arbitrary code with the privileges of the user running the application. This vulnerability aligns with CWE-457, which describes "Use of Uninitialized Variable" and represents a significant risk in enterprise environments where PDF documents are frequently exchanged. The ATT&CK framework categorizes this as a code injection technique under T1059, where an attacker leverages a parsing vulnerability to execute malicious code.
Mitigation strategies for this vulnerability require immediate patching of affected Foxit Reader installations, as the vendor released updates to address the JBIG2 parsing issue. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive the security updates promptly. Additionally, network security controls such as PDF content filtering and sandboxing mechanisms can provide defense-in-depth protection by analyzing PDF content before it reaches end-user systems. Email security solutions should be configured to scan PDF attachments for malformed JBIG2 data structures, while web-based PDF viewers should be updated to use more secure parsing libraries. The vulnerability demonstrates the importance of proper input validation in multimedia processing components and highlights the need for robust memory safety practices in document rendering engines. System administrators should also consider implementing application whitelisting policies to restrict execution of untrusted PDF documents and monitor for suspicious PDF-related activities in network traffic.