Wallet hack
A wallet hack describes a situation in which someone gains unwanted access to a wallet and can move the balance. That can happen through stolen keys, deception or a flaw in software. Whether an unexpected movement really is a hack cannot be established with certainty from the transaction alone.
What it may indicate
A wallet that empties without permission can point to unwanted access, but equally to something else, such as a forgotten authorisation. Sometimes it is less clear cut than it looks. What actually happened only emerges from investigating the transactions and the access that preceded them.
What is a wallet hack?
A situation in which someone gains unwanted access to a wallet and can move the balance, for example through stolen keys, deception or a software flaw.
Can you tell from a transaction whether it was a hack?
Not with certainty from the transaction alone. What happened only emerges from investigating both the movement and the access that preceded it.