While hardware wallets protect your keys from basic computer malware, the firmware inside the device is software—and software can theoretically be compromised.
The Malicious Firmware Threat When you update your Trezor or Ledger, you are flashing new software onto the device. If a hacker managed to compromise the manufacturer's update servers, they could potentially push a malicious update that secretly alters how the device signs transactions or leaks the seed phrase.
How Manufacturers Prevent This: 1. Cryptographic Signatures: Your hardware wallet will mathematically verify the "digital signature" of any firmware update before installing it. If the firmware wasn't signed by the official Ledger/Trezor master keys, the device will reject it and refuse to boot. 2. Open Source Audits: Trezor's firmware is 100% open source. Security researchers globally review the code for backdoors or accidental vulnerabilities. 3. Secure Elements: Ledger uses proprietary chips that are heavily audited by third-party security labs (like ANSSI in France) to ensure the firmware cannot be tampered with.
The Real Danger: Social Engineering The most common "hack" isn't a firmware breach; it's a fake app. Hackers will publish a fake "Ledger Live" or "Trezor Suite" app on the Google Play Store or via a phishing website. When you open the fake app, it tells you there's an error and asks you to manually type your 24-word seed phrase into your keyboard.
Rule #1 of Crypto: Your hardware wallet will NEVER ask you to type your 24 words into a computer keyboard. You only ever enter them on the physical device itself.