Mercedes-Benz vehicles are known for luxury and innovation. Their infotainment systems are cutting-edge, providing seamless user experiences. However, even the most advanced tech isn’t immune to security flaws.

CVE-2023-34399 is a critical vulnerability affecting Mercedes-Benz’s NTG6 head units, letting attackers exploit a flaw via USB profile imports/exports. The vulnerability lies in the use of an outdated Boost library for deserializing user profile archives—opening the door to integer overflow and potential remote code execution (RCE).

This post will break down the vulnerability, how it works, and provide code snippets for demonstration. We’ll also discuss real-world attack scenarios and share links to official sources.

What is CVE-2023-34399?

CVE-2023-34399 is an integer overflow vulnerability found in certain Mercedes-Benz car infotainment systems (head-unit NTG6). The system lets drivers back up or restore personal settings—like favorite radio stations, seat positions, or navigation preferences—via a connected USB stick.

Under the hood, the head unit serializes these profile settings using the open-source Boost C++ library. Unfortunately, the version of Boost included was outdated and harbored a bug: it didn’t correctly check input sizes when deserializing data. This makes it possible for attackers to craft malicious profile files that trigger an integer overflow, causing the head unit to behave unpredictably—or, in the worst case, running unauthorized code.

Malicious archive feeds large size values that aren’t properly checked.

4. Integer overflow happens, letting extra/invalid data slip through checks.

Technical Deep-Dive: The Boost Serialization Bug

In the NTG6 system, user profiles are saved as Boost-serialized archives (often in binary or XML format). A crafted archive can have metadata fields like arrays or string lengths set to huge values.

The vulnerable Boost code (from collections_load_imp.hpp in the serialization library) did not properly check for integer overflows. Here’s a simplified snippet demonstrating the issue (vulnerable logic in Boost):

// Vulnerable deserialization code in Boost
std::size_t count;
ar >> count; // reads count from archive (untrusted)
std::vector<T> collection;
collection.reserve(count); // if 'count' is too large, integer overflow!

// On certain inputs, 'count' wraps, allocating less memory than needed
// Later, copy code overflows vector, causing memory smash.

A real-world attacker creates an archive like this (pseudo-XML)

<collection>
  <count>4294967295</count> <!-- Overly large number triggers overflow -->
  ...
</collection>

Exploiting the Vulnerability on Mercedes-Benz NTG6

Imagine an attacker with physical access to a Mercedes NTG6 head unit (say, at a valet). They prep a USB stick with a malicious profile.dat exploiting this bug.

1. Social engineering: "Let me set your system with this latest update/recommendation" or just subtly leave the USB behind.

User plugs in USB and imports profile.

3. Integer overflow triggers during import, potentially crashing the head unit—or worse, allowing the attacker's code to run (showing a fake update screen, exfiltrating data, or installing a persistent backdoor).

Here is a high-level exploit strategy (NOT a full weaponized exploit, but enough to understand)

1. Create a profile archive using Boost’s boost::archive::binary_oarchive but manually edit the generated file to replace size fields with xFFFFFFFF (max unsigned 32-bit).

*Example: Generating a "bad" serialized archive with Python for fuzzing:*

with open("bad_profile.bin", "wb") as f:
    # Write binary header for Boost archive (simplified)
    f.write(b"serialization::archive 12\n")
    # Insert maliciously large count
    f.write((4294967295).to_bytes(4, "little"))
    # Add fake (or real) serialized data
    f.write(b"A" * 100)

Warning: Never try this on production vehicles. Only use in a sandbox/test environment.

Who is affected?

Mercedes-Benz vehicles equipped with the NTG6 head unit and accepting USB profile imports/exports.

Mitigation and Patches

Mercedes-Benz has released patches for affected vehicles.
If you own a Mercedes model with NTG6, check with your dealer for infotainment updates.

Resources and References

- Official CVE Entry: CVE-2023-34399
- Boost Serialization Vulnerability Report
- Mercedes-Benz Infotainment Security Updates
- Boost Serialization Docs

Conclusion

CVE-2023-34399 is a reminder that even luxury cars can have real, exploitable security flaws stemming from widely used, open-source components. If you drive a Mercedes-Benz with NTG6, keep your firmware safe and apply updates — or risk more than just your playlist or navigation favorites falling into the wrong hands.

Stay secure — and, as always, watch what you plug in!


*This post is an exclusive analysis for educational purposes, summarizing what’s currently known about this Mercedes-Benz vulnerability. All code is for demonstration only.*

Timeline

Published on: 02/13/2025 22:15:10 UTC
Last modified on: 03/24/2025 17:15:15 UTC