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Smelltu Hér
Guðmundur Karl Karlsson
Independent contractor in security research. I build tools that use AI to find vulnerabilities faster — and to help defenders fix them first.
01 About
I have more than 20 years in the technology sector, most recently as a security architect in cyber security at Íslandsbanki. I first made a name for myself on the Defend Iceland bug bounty platform, where I became one of its top-ranked hackers by finding previously unknown weaknesses in a wide range of systems.
That led to a role at Defend Iceland in research and development, building AI-powered security solutions and researching vulnerabilities in new ways. Through Smelltu Hér I take on independent security research and develop tools that put AI to work for both offensive research and defensive purposes.
- Ranked
- Top-ranked on Defend Iceland
- Spoke at
- DEF CON 33 · Recon Village
- Teaching
- Reykjavík University, Nov 2026
- Experience
- 20+ years in tech
02 Talks, writing & teaching
Talk · DEF CON 33 · Recon Village · 2025Plumbing the Plumber: A Playbook for Integration Servers
A playbook for attacking integration servers — the middleware plumbing at the heart of enterprise systems.
View on reconvillage.org ↗How I found all corporate usernames in Iceland
Chaining publicly reachable registry data with Microsoft 365 behaviour to enumerate valid corporate accounts across the country — and what organisations must do about it.
Read ↗ Essay · Defend Iceland · Jun 2026Is your CTO vibe-coding?
AI-assisted coding ships features faster — and vulnerabilities too. Why experienced review and security testing must stand between generated code and production.
Read ↗ Course · Reykjavík University · 18 Nov 2026Örugg notkun á gervigreind til forritunar
Safe use of AI for programming: building a full web application with AI assistance, from concept to deployment, with security from day one. Co-taught with Dr. Anna Sigríður Islind.
Course page ↗ Press · ViðskiptablaðiðVinnur að þróun á gervigreindarhakkara
Working on the development of an AI hacker — on joining Defend Iceland from Íslandsbanki to build AI-powered security research tools.
Read on vb.is ↗