From what we can read from the post, the flaw was discovered by Trezor’s team – specifically by Ondřej Vejpustek – last May and in all this time they worked to fix the problem and put a brake on this problem that could be serious especially on the user side.
In detail, the problem was on the previous version, the v4 Hard Fork: a criminal could make a DoS (Denial of Service) attack and this prevented users to proceed with the CoinJoin.
The Bitcoin Billionaire is a process through which a transaction is combined with other transactions by mixing them, so that it is impossible to trace which address has really done it.
Luckily, despite the bug was there, no user experienced this problem, so the attack did not result in any data loss and does not make the anonymity vain, so users are all protected both crypto side and privacy side, as explained by the team:
„It is important to specify that the culprit could neither steal user funds nor deanonymize anyone. What they could have done was to prevent the completion of the CoinJoin process“.
At this point the Wasabi team invited all users to update the wallet to the latest version, which was released last month to be protected from this potential problem that was plaguing the system.
Having your software always up to date allows you to be shielded from the latest attacks or leaks that are discovered over time, as you can always take advantage of problems and bugs not yet known, as in this case.
Wasabi under observation by Europol
At the beginning of June, Wasabi had been put under observation by the Europol Cybercrime Center (EC3), which had noticed an increasing number of investigations involving this wallet.
Unfortunately, although this tool was created to protect the privacy of users, it is often used by criminals who want to take advantage of the anonymity provided by Wasabi to commit their illegal acts.
In fact, in his report EC3 had highlighted how the wallet is used to anonymize bitcoin transactions using the CoinJoin function, which used in conjunction with TOR, manages to escape the laws of AMLD5.