Estimates on infection vary but it is believed that at its peak DNSChanger infected four million PCs, including sizable numbers . An original cut-off date of 8 March was extended to 9 July to allow more users to remove the malware.

Given the widespread warnings issued by numerous companies over several months, it is likely that a significant number of users will not react in time. Google's latest campaign follows up on a similar one launched as long ago as last summer.

Advice on dealing with DNSChanger can be found but removing the redicrection might not be the end of a user's troubles - in recent times DNSChanger infection by other forms of malware that will need to be dealt with separately.