Fuzz testing was long considered a specialist discipline for security researchers. The EU Cyber Resilience Act (CRA) is fundamentally changing this: manufacturers must demonstrate that their products have been systematically tested for vulnerabilities. Fuzzing is one of the most effective tools for this purpose.

What the CRA Requires

The CRA requires, among other things:

  • Security by Design throughout the entire product lifecycle
  • Documented security tests before placing on the market
  • Verifiable vulnerability management

Classical penetration tests cover targeted attacks. Fuzzing complements this through automated breadth search for vulnerabilities that are easily overlooked in manual testing – especially memory corruption bugs in C/C++ code.

Fuzzing for Embedded Systems

The challenge with embedded targets lies in the environment: proprietary hardware, real-time operating systems, and limited debugging capabilities. The following approaches are particularly effective:

Coverage-guided Fuzzing

Tools like AFL++ and libFuzzer maximize code coverage through intelligent input generation. Developing suitable fuzz harnesses is the critical success factor.

Protocol Fuzzing

For communication interfaces – whether CAN, Bluetooth, or proprietary protocols – structured fuzzing that considers the protocol grammar and specifically tests edge cases is well suited.

Why Fuzzing Complements Manual Testing

Fuzzing and manual code analysis are complementary methods. While experienced analysts identify logic errors and design weaknesses, fuzzing systematically finds input combinations that simply cannot be covered manually – especially in complex parsers and protocol implementations with large input spaces.

For example, coverage-guided fuzzing identified three previously unknown buffer overflows in a firmware parsing library within 72 hours – triggered by specific input sequences that no manual test can systematically cover given the sheer size of the input space.

proofnet supports the introduction of fuzz testing – from strategy to harness development. Learn more about our security testing services or request directly.