[walexander]

The most plausible theory I've heard is that the attackers used a BTC tumbler that was a honeypot controlled by feds.

But who knows, maybe the FBI has a quantum computer we don't know about.

[Taek]

Seems unlikely that the FBI sitting on a way to break ECDSA would use it to recover $2 million. Much more likely that there was a tumbler or exchange that they were able to link to the attacker and use to seize funds. Maybe they even have backdoors in some popular crypto wallets.

[mmaunder]

Might cost more than $2MM in compute, but could be worth it to demonstrate capability.

[lordnacho]

Sounds plausible, that one. Also perhaps the ransom gang had a staging server with a bunch of keys somewhere.

But the tumbler idea actually seems more plausible to me.

[answertojob]

they don't :(