X41 D-Sec GmbH

We are a renowned expert provider for dedicated high quality security research, application security services, penetration tests, and full red teaming. Having extensive industry experience and expertise in the field of IT security, a highly effective security team of world class security experts enables X41 to perform premium security services.

Fields of expertise in the area of application security are code reviews, binary reverse engineering, and vulnerability discovery. Custom research and high quality IT security services are core competencies of X41

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About X41

Our Philosophy

  • Lock

    Making you safer

    Finding Vulnerabilities Before Others do.

    We are experts in security testing. We enable you to make your products and infrastructure safe and sound.

  • Pencil


    Be Secure by Design.

    Secure design is the base of quality products and systems. Rely on our expertise in security design.

  • Rocket


    Show investors you live up to their trust.

    Believing in start-up-culture we care for them! We help you gaining an advantage.

  • Our


What we do.




We have the expertise in code reviewing, red teaming and penetration testing, and security design reviews of a wide variety of products. Finding defects will improve the quality of your products.

Vulnerability Management


We help you handle vulnerabilities in products you use or develop. We take care of vendor contacts and work out the technical details with security researchers and developers to do vulnerability reporting in a professional way. Years of experience in uncovering vulnerabilities created an expert process in getting vulnerabilities fixed.


  • Application Security (APPSEC)
  • Mobile Security
  • Embedded Security
  • Network Security
  • Cloud Security


X41 At Conferences in 2/2018

The X41 team will be at multiple conferences in the second part of 2018. Read more

Wire Application Level Audit (with Kudelski Security)

X41 D-Sec's Markus Vervier and Kudelski Security's JP Aumasson reviewed the Wire application stack for Android, iOS, and Web. Read more

How To Protect Against WebUSB U2F Phishing

X41 shows how to protect against attacks targeting U2F tokens via WebUSB. Read more

X41 - Security Research Lab

Serious research requires serious expertise.

Vulnerability Research


There is no defense without understanding offense. Security Research is essential to keep up with emerging threats. From uncovering new vulnerabilities to creating better mitigations we are a strongly research driven company.

Mitigation and Hardening


No application is bug-free. A good security concept will include measures to harden and mitigate yet unknown vulnerabilities making it harder for an adversary to exploit them. We develop new techniques to mitigate exploitation and contain threats.

If you are interested in custom research contact us.


Is security your passion? Do you like being creative? Do you want to face new challenges to expand your skills even further? Contact us, we're hiring!

Contact Us

Office Locations:

Aachen Frankfurt