Threat Modeling OTP Flows
Map assets, actors and trust boundaries, then walk the attacks that actually hit OTP flows — SIM swap, real-time relay, push bombing, pumping — and score the mitigations consistently.
Requires: OTP Cryptography Internals
Chapters
- 1
Building the threat model: assets, actors, trust boundaries
Draw the flow before you defend it. A one-page model of what is valuable, who wants it and where trust changes hands.
6 min read
- 2
SIM swap: chain of attack and controls
Follow a number port from reconnaissance to account takeover, then place controls at each link where your system can still see it.
6 min read
- 3
Adversary-in-the-middle and real-time OTP relay
Model the relay proxy as an actor, find the signals it leaves, and decide which mitigations change the outcome rather than the odds.
6 min read
- 4
MFA fatigue and push bombing
When the second factor is a button, attackers press it for you until someone gives in. Model the attack and design approvals that resist it.
6 min read
- 5
SMS pumping / toll fraud as an OTP-flow threat
An attacker who never wants your accounts can still bill you. Model the send endpoint as an asset and gate it accordingly.
6 min read
- 6
Scoring and documenting mitigations
A four-level severity rubric, applied the same way everywhere, turns a list of threats into decisions leadership can actually make.
6 min read