Malware

Malware is software that runs on a victim's computer or phone against their interest. Crypto-targeting malware includes keyloggers that capture passwords and typed recovery phrases, clipboard hijackers that replace a copied address with the attacker's, info-stealers that read wallet files and browser extensions, and fake wallet apps.

A software wallet keeps its keys on the infected device, so malware can often take them. A hardware wallet keeps keys on a separate device and asks for confirmation on its own screen, so malware can show a fake address on the computer but cannot sign without the user. The protection holds only if the user checks the address on the device screen.

Typing a recovery phrase into any computer or phone defeats this separation entirely.