 As of , Microsoft claims that the software has removed password stealer threats from 859,842 machines.In August 2013, the Malicious Software Removal Tool deleted old, vulnerable versions of the Tor client, in order to end the spread of the Sefnit botnet (which mined for bitcoins without the host owner's approval and later engaged in click fraud).Approximately two million hosts had been cleaned by October; although this was slightly less than half of the estimated infections, the rest of the suspected machines presumably did not have their automatic Windows Updates enabled or manually run.