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Kai Greshake
Verified Expert in Engineering
C# Developer
Saabrücken, Germany
Toptal member since June 15, 2017
Bio
Kai works in the field of IT security. He's a seasoned developer and security consultant. Having worked on projects of all sizes with remote and local teams, Kai can deliver standalone high-performance applications for use in a back-end environment, penetration testing, and general security consultation. Kai's high-quality education in computer science allows him to understand and apply complex subjects efficiently.
Portfolio
sequire
Security Testing, IoT Security, Web App Security
KORAMIS
Incident Response, Penetration Testing, Security
Center for IT-Security, Privacy, and Accountability
Python, Rust, C++, C, .NET Core
Experience
- C# - 6 years
- Python - 5 years
- C - 5 years
- Linux - 5 years
- Concurrent Programming - 3 years
- Security Testing - 3 years
- Rust - 2 years
- Cryptography - 2 years
Work Experience
Pentester | Consultant
2022 - PRESENT
sequire
- Developed highly secure software drivers for industrial computing.
- Tested products, applications, and infrastructure offensively to help companies improve their security posture.
- Developed partially automated reporting tools to cut time spent writing penetration testing reports by two-thirds while producing higher-quality output.
Technologies: Security Testing, IoT Security, Web App Security
Cyber Security Engineer | Penetration Tester
2019 - 2021
KORAMIS
- Coached many customers to identify security issues and efficiently fix them.
- Assisted companies in incident response, responding to attacks and mitigate them.
- Surveyed industry-standard tooling for vulnerabilities to help customers maintain a secure stance. Identified many issues, including a critical vulnerability in Symantec Critical Systems Protection software which protects industrial plants worldwide.
Technologies: Incident Response, Penetration Testing, Security
Security Researcher
2015 - 2019
Center for IT-Security, Privacy, and Accountability
- Developed high-performance software for the parallel calculation of advanced anonymity metrics.
- Analyzed the security of Android apps generated using app generators such as Appy Pie and SeattleCloud.
- Implemented a fuzzing environment and tools to fuzz the Android middleware.
Technologies: Python, Rust, C++, C, .NET Core
Software Developer
2014 - 2015
KS Software (now xbAV)
- Developed a financial consultation back-end (calculation of taxes, interest rates, and more).
- Worked on a UI using WPF for the consultation process.
- Implemented quality-control measures (unit tests).
Technologies: Visual Studio, Git, Windows Presentation Foundation (WPF), .NET
Freelance Developer
2012 - 2014
RS Wägetechnik
- Developed a back-end calculating the advanced metrics over the calibration data collected from various high-precision measurement devices.
- Built a login system and infrastructure with access control and user management.
- Designed and implemented a front-end desktop application interface to input and manage calibration data.
Technologies: Git, Visual Studio, Windows Presentation Foundation (WPF), .NET
Project History
Contact Tracing Gateway System for Germany
I helped develop the security model and implementation of IRIS connect, a nationwide service in Germany that helps local health departments collect contact tracing information from the various app providers. It will be used in the majority of Germany's health departments.
Bsc Thesis on Fuzzing (Automated Software Testing)
https://www.dropbox.com/s/43ovybqfiugen1w/thesis_greshake.pdf?dl=0In this study, I benchmark various different optimization algorithms on their fuzzing capabilities to find that constraint solving with optimization might not have been the key to Angoras performance. Nonetheless, results show promising directions for future research and will expand the performance and use cases for fuzzing in the future.
There's a blog post about it: https://andreas-zeller.blogspot.com/2019/10/when-results-are-all-that-matters-case.html
There's a blog post about it: https://andreas-zeller.blogspot.com/2019/10/when-results-are-all-that-matters-case.html
i3status-Rust
https://github.com/greshake/i3status-rustThis is a very resource-friendly and feature-rich replacement for i3status; written in pure Rust. An open-source project that I've started and continue to maintain.
QuoteBot (German)
A neural network bot trained on quotes from famous people, generating new "wisdom" which self-improves through user feedback. It posts content on its own Facebook page. Currently it's only in German and is not active right now. The feedback home page also is currently not online due to the cost of operation.
Dieter Meurer Award
This is an award for achievement in the field of legal computer science, pertaining in this case to my responsible disclosure of open-access database breaches (early '15). The link refers to the paper that we published in response to the incident.
Specialized Lectures
These are some of the specialized courses that I attended in university:
- Web Security
- Cryptography
- Secure Software Engineering
- Security Testing
- Cybersecurity
- Cybersecurity Project
- Security (Advanced Lecture)
- Hacking
- Mobile Security
I'm happy to answer any further questions about the topics covered.
- Web Security
- Cryptography
- Secure Software Engineering
- Security Testing
- Cybersecurity
- Cybersecurity Project
- Security (Advanced Lecture)
- Hacking
- Mobile Security
I'm happy to answer any further questions about the topics covered.
Industrial Software Vulnerabilities
Broadcom's Critical Systems Protection software is used around the world in industrial facilities.
During my work as a penetration tester, I've uncovered many critical software vulnerabilities like this one:
https://support.broadcom.com/security-advisory/content/0/0/SYMSA1498
During my work as a penetration tester, I've uncovered many critical software vulnerabilities like this one:
https://support.broadcom.com/security-advisory/content/0/0/SYMSA1498
Dell Software Security Acknowledgment Program
This program was made for the vulnerabilities in the Dell update system which I discovered and helped to fix.
Education
2014 - 2018
Bachelor's Degree in Cybersecurity
Saarland University - Saarbrücken, Germany
Skills
Tools
Microsoft Visual Studio, PyCharm, Git, Visual Studio, IntelliJ IDEA, CLion
Languages
C#, Python, C++, Go, SQL, Rust, C, Java
Platforms
Linux, Android
Paradigms
Concurrent Programming, Penetration Testing, Agile, Software Testing
Frameworks
.NET, Windows Presentation Foundation (WPF), Django, Flask, ASP.NET, .NET Core
Industry Expertise
Cybersecurity
Storage
MongoDB, PostgreSQL
Other
Cryptography, Security Testing, Security, Incident Response, IoT Security, Web App Security
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