Senior identity security advice, delivered personally
Nimbus Cyber is an Athens-based advisory practice focused on one question: who and what can reach your critical systems, and can you prove it is justified? Founded in 2024 by Kostas Tsiolas, after 8 years leading identity security work at Microsoft across Europe.
Kostas Tsiolas
Cybersecurity Advisor & Identity Security Architect
CISSP · CCSP · Microsoft Cybersecurity Architect Expert · Ex-Microsoft
I have spent 25 years in enterprise IT and security, from Greek financial institutions to 8 years leading identity security work at Microsoft across Europe. I have been the engineer who builds the systems and the advisor who tells leadership what is broken.
I founded Nimbus Cyber in 2024 because most breaches now start with a login, not a break-in. Identity, human and non-human, is where security is won or lost.
Every engagement is led by me personally, with trusted specialist partners in GRC, cloud architecture and regulatory compliance where needed.
Certifications
Security and identity: CISSP, CCSP, CCSK, Certified Identity and Access Manager, Certified AI Security Specialist
Microsoft: Cybersecurity Architect Expert, Identity and Access Administrator, Azure Security Engineer Associate, Azure Solutions Architect Expert, Microsoft 365 Administrator Expert
Verify on Credly
Why Nimbus?
Nimbus takes its name from the Latin word for cloud, but the inspiration is Greek. In Homer, the gods protect the people they favour by wrapping them in a cloud: Athena shrouds Odysseus in mist so he can walk into the city of the Phaeacians unseen. Nearly three thousand years later, the cloud still has to protect the right people. Now that organisations run on cloud services, they must decide who — or what — can reach their systems and data, and under what conditions.
For Nimbus Cyber, identity sits at the heart of those decisions.
How we work
Proactive before reactive
We help you build the controls before an incident forces the issue. It costs less and is easier to defend.
Architecture before tools
We design the architecture first, then help you choose and configure tools that fit it. Our recommendations are not tied to any vendor.
Boardroom to terminal
We brief boards in terms of business risk and regulation, and engineers in terms of specific controls and configurations.
Personally delivered
Every engagement is led by Kostas, in English or Greek, remotely or on site across Europe.