Threat Modelling in Practice

STRIDE — Spoofing, Tampering, Repudiation, Information Disclosure, Denial of Service, Elevation of Privilege — is a threat-modelling framework originally developed at Microsoft. Applied to a wallet, it surfaces threats that pure crypto analysis misses.

Spoofing: a phishing site impersonates your wallet provider's UI. Tampering: malware modifies the transaction you are about to sign, changing the recipient address after you have verified it on screen but before it reaches the signing device. Information Disclosure: clipboard managers or screen-share software expose your mnemonic during backup. Each category produces a concrete, testable threat you can mitigate.

The output of a STRIDE exercise is a table: threat → asset at risk → likelihood → impact → mitigation. This table becomes your operational security checklist.

Hot wallets (browser extensions, mobile apps) keep the private key on a network-connected device. They are convenient but sit in the richest attack environment. Warm wallets add a layer — a hardware wallet that must physically approve each transaction, but is connected to a computer during signing. Cold wallets keep the signing device fully air-gapped; transactions are transported via QR code or SD card.

The trade-off is always speed-of-access vs. attack surface. A trading desk needs hot wallets for sub-second execution. A corporate treasury holding reserves should never need hot access. The mistake most teams make is using the same custody model for operating funds and reserves.

The device running your wallet is part of the trust boundary. A compromised OS can keylog your password, swap clipboard addresses, or extract keys from memory. Hardening means: keep the OS updated, use full-disk encryption, disable browser extensions on the wallet machine, and — ideally — dedicate a device exclusively to signing.

For teams, device posture assessment should be part of onboarding: is the laptop encrypted? Is the browser profile clean? Is the wallet software downloaded from the official source and checksum-verified? These are not exotic controls; they are baseline hygiene that prevents the most common losses.