It wouldn't be easy, but I'm imagining it would probably require identifying the other side of some historical transactions, and being able to prove that. Like if you had ever sent to/from any other address you held the key to, you could sign a transaction from that other address.
Don't know much about bitcoin, but if they know which numerical wallet it came from, can't send it back even if they don't know the person who owned it or communicating with that owner?
Like if I woke up one morning and found money in my bank account that wasn't supposed to be there, I could just tell the bank to send it back where it came from.
The original wallet is compromised so if you send the money back the attacker can immediately re-steal it. The original owner could try to out-RBF the attacker but game theoretically that leads to the money being converted to miner fees.
The underlying issue here is that addresses created by the tool at fault can have their private key derived from public data. If you send it back, it'll just get stolen again. Furthermore, the typical way that someone proves ownership of an address is by making a transaction from that address with parameters set via private communication with someone else. But since the private key is knowable, anyone can do that. There's no generic way to prove ownership of an address if the private key associated with that address can be determined by an attacker.
Conceivably, the funds could be sent to an address that they send to before. Very far from perfect... could work if it's a centralized exchange, one could deposit to the same address more than once (or maybe there's a time limit for re-use iunno). And no way (good?) way of knowing you were sending to your own account on that exchange, or somebody else's.
The STM32 in the ColdCard has a 96-bit UID "fused" at the factory. The lower 32 bits of this are seeded into the Yasmarang PRNG's initial state. Possession of a ColdCard with a UID matching a contested wallet might be able to serve as evidence of ownership.
in other words, this attack could link together different wallets created on the same coldcard?
Yes. Huge boon for chain analysis companies, even in cases where the coins moved long ago and are no longer sweepable.