Defensive Cybersecurity
Like Duolingo, but for Defensive Cybersecurity. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
For the part of you with thirty open tabs that never became anything.
21 levels across 3 sections, about 42 minutes end to end, roughly 8 days at five minutes a day. It moves through Auditing Access and Attack Surfaces, Interpreting Attacks and Lateral Movement, and Engineering Resilient Architecture. It assumes you already know the basics.
Free forever · No credit card · iPhone & Android
Key ideas in Defensive Cybersecurity
- FIDO2 cryptographically binds the challenge response to the browser's origin domain
- Adversary-in-the-middle proxies easily relay one-time codes to the legitimate service
- Browsers refuse to release credentials if the proxy domain mismatches the registered relying party
- Session cookies prove authentication already succeeded and bypass re-evaluation
- MFA gates initial session issuance but does not continuously re-verify every HTTP request
- Stealing tokens via malware or infostealers neutralizes upstream MFA protections
- Static credentials only verify identity claim, not environmental risk signals
- Impossible travel calculations detect logins across distant physical locations too quickly
- Device compliance checks verify MDM enrollment, disk encryption, and OS patch levels
- Automated service accounts often skip MFA because headless scripts cannot enter push prompts
- Hardcoded API keys without rotation lifetimes persist silently in repositories and backups
- Privilege creep happens when service identities retain broad roles across multiple revisions
- Accounts sit unprivileged by default until elevated access is explicitly requested
- Approval workflows and automated policy checks validate the justification before elevation
- A time-to-live expires permissions automatically without requiring manual revocation
- Repudiation attacks compromise non-repudiation by denying an action occurred
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives Defensive Cybersecurity the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
Why do tools like Evilginx defeat standard one-time codes (TOTP) so easily?
Get it right to open this lesson and 20 more in the app.
Where Defensive Cybersecurity takes you
Bridge the gap between basic security hygiene and enterprise defense. Learn how modern attackers move laterally through systems and how to engineer resilient, threat-informed security architectures.
- 1
Auditing Access and Attack Surfaces
- Hardening Identity and Session Boundaries
- Threat Modeling and Surface Analysis
- 2
Interpreting Attacks and Lateral Movement
- Deconstructing Lateral Movement and Exploitation
- Investigating Breaches with Telemetry
- 3
Engineering Resilient Architecture
- Implementing Zero Trust and Network Segmentation
- Prioritizing Vulnerabilities and Mitigations
- Incident Response and Disaster Recovery
3 sections · 7 units · 21 levels. Built to play, not to enroll.
You pick the voice
Defensive Cybersecurity is taught in the The Professor style: clear, structured, thorough. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
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Start Defensive Cybersecurity today.
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