CVE-2021-38564 in Foxit
Summary
by MITRE • 08/12/2021
An issue was discovered in Foxit PDF Reader before 11.0.1 and PDF Editor before 11.0.1. It allows an out-of-bounds read via util.scand.
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Analysis
by VulDB Data Team • 08/16/2021
The vulnerability identified as CVE-2021-38564 represents a critical out-of-bounds read flaw affecting Foxit PDF Reader and PDF Editor versions prior to 11.0.1. This issue stems from improper input validation within the util.scand component, which processes PDF file structures and data parsing operations. The flaw manifests when the application attempts to read memory locations beyond the allocated buffer boundaries during PDF document processing. Such vulnerabilities typically arise from inadequate bounds checking mechanisms that fail to validate array indices or memory access limits before data retrieval operations. The affected util.scand function likely handles scanning operations for various PDF elements including text streams, object structures, or metadata fields where insufficient boundary validation permits unauthorized memory access patterns.
Security implications of this out-of-bounds read vulnerability extend beyond simple data corruption or application crashes. The flaw can potentially enable attackers to extract sensitive information from memory locations adjacent to the targeted buffer, including credentials, encryption keys, or other confidential data. This type of vulnerability falls under the CWE-129 category of "Improper Validation of Array Index" and represents a variant of memory safety issues that have been extensively documented in cybersecurity literature. The attack vector typically involves crafting malicious PDF files containing specially designed payloads that trigger the vulnerable code path when the application attempts to parse or render the document. This vulnerability can be exploited through social engineering techniques where users are tricked into opening maliciously crafted PDF documents, making it particularly dangerous in enterprise environments where PDF documents are frequently exchanged.
The operational impact of CVE-2021-38564 can be severe for organizations relying on Foxit PDF applications for document processing and collaboration. Successful exploitation may result in information disclosure, application instability, or potentially remote code execution depending on the specific memory layout and surrounding code context. The vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1566 for Phishing, as it requires user interaction with malicious documents to achieve exploitation. Organizations may experience service disruptions, data breaches, or compliance violations if the vulnerability is exploited in the wild. The flaw particularly affects environments where PDF processing is automated or where documents are processed in batch modes, as these scenarios may amplify the potential impact of the out-of-bounds read condition.
Mitigation strategies for this vulnerability should prioritize immediate patching of Foxit PDF Reader and PDF Editor applications to versions 11.0.1 or later where the issue has been resolved. System administrators should implement strict document validation policies and consider deploying sandboxing mechanisms for PDF processing operations. Network security controls including web application firewalls and content filtering solutions should be configured to scan and block suspicious PDF files. Organizations should also consider implementing least privilege access controls for PDF processing applications and regularly monitor for anomalous system behavior that might indicate exploitation attempts. The fix typically involves implementing proper bounds checking mechanisms within the util.scand function to validate all array indices and memory access operations before data retrieval, ensuring that buffer overflow conditions cannot occur during PDF parsing operations. Additionally, regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other document processing applications within the organization's infrastructure.