CVE-2024-23313: Libbiosig Integer Underflow RCE Flaw

CVE-2024-23313 Overview

An integer underflow vulnerability exists in the sopen_FAMOS_read functionality of The Biosig Project libbiosig. This critical vulnerability affects libbiosig version 2.5.0 and the Master Branch (ab0ee111). When processing a specially crafted .famos file, the integer underflow can lead to an out-of-bounds write, which in turn enables arbitrary code execution. An attacker can provide a malicious file to trigger this vulnerability.

Critical Impact

This vulnerability allows remote attackers to achieve arbitrary code execution by convincing a user to open a malicious .famos file, potentially leading to complete system compromise without requiring authentication.

Affected Products

• libbiosig_project libbiosig version 2.5.0
• libbiosig_project libbiosig Master Branch (ab0ee111)
• Fedora Project Fedora 40

Discovery Timeline

• 2024-02-20 - CVE-2024-23313 published to NVD
• 2025-11-04 - Last updated in NVD database

Technical Details for CVE-2024-23313

Vulnerability Analysis

The vulnerability resides in the sopen_FAMOS_read function within the libbiosig library, which is responsible for parsing FAMOS file format data. The core issue is an integer underflow (CWE-191) that occurs during size calculations when processing malformed .famos files. When a crafted file contains specific values that cause an arithmetic underflow, the resulting value becomes unexpectedly large, leading to an out-of-bounds write condition.

The libbiosig library is commonly used for reading and converting biomedical signal data files. Applications that integrate this library to handle .famos format files are vulnerable if they process untrusted input files.

Root Cause

The root cause is improper validation of numeric values during file parsing operations in the sopen_FAMOS_read function. When performing arithmetic operations on file-supplied values, the code fails to check for underflow conditions. This allows an attacker to supply values that, when subtracted, wrap around to very large positive numbers due to the unsigned integer representation. The resulting oversized value is then used in memory allocation or buffer operations, creating an out-of-bounds write primitive.

Attack Vector

The attack vector for CVE-2024-23313 is network-based, requiring no privileges or user interaction according to the CVSS vector. An attacker can exploit this vulnerability by:

1. Crafting a malicious .famos file with specific field values designed to trigger the integer underflow
2. Delivering the file to a victim through various channels (email attachment, file sharing, web download)
3. When the victim or an automated system processes the file using a vulnerable version of libbiosig, the underflow occurs
4. The out-of-bounds write corrupts memory in a controlled manner
5. The attacker achieves arbitrary code execution in the context of the application processing the file

The vulnerability is particularly dangerous because biomedical data processing applications may automatically process incoming files without manual intervention, enabling automated exploitation scenarios.

Detection Methods for CVE-2024-23313

Indicators of Compromise

• Presence of unusually large or malformed .famos files on systems or in email attachments
• Application crashes or unexpected behavior in software utilizing libbiosig when processing .famos files
• Memory access violations or segmentation faults in processes linked to libbiosig
• Unexpected child processes spawned from applications that typically process biomedical signal data

Detection Strategies

• Monitor for abnormal process behavior in applications that use libbiosig for file processing
• Implement file integrity monitoring on directories where .famos files are commonly stored or processed
• Use endpoint detection and response (EDR) solutions to detect memory corruption exploitation attempts
• Deploy application-level logging to capture file processing errors and anomalies

Monitoring Recommendations

• Enable verbose logging for applications utilizing the libbiosig library
• Monitor system calls for unusual memory allocation patterns from biomedical data processing applications
• Implement network monitoring to detect suspicious file transfers involving .famos files
• Configure alerts for application crashes or restarts in systems processing biomedical signal data

How to Mitigate CVE-2024-23313

Immediate Actions Required

• Update libbiosig to a patched version that addresses CVE-2024-23313
• Restrict processing of .famos files from untrusted sources until patches are applied
• Implement input validation and file scanning for any .famos files before processing
• Consider sandboxing or containerizing applications that process biomedical signal data

Patch Information

For Fedora users, apply the latest security updates as referenced in the Fedora Package Announcement. For other systems using libbiosig directly, consult The Biosig Project for updated releases. Additional technical details are available in the Talos Vulnerability Report TALOS-2024-1922.

Workarounds

• Disable or remove the ability to process .famos files if not required for business operations
• Implement strict file type validation before allowing files to be processed by libbiosig
• Run applications that process biomedical signal data with reduced privileges in isolated environments
• Deploy application whitelisting to prevent execution of unauthorized code that could be delivered via exploitation