Virus writers have developed a worm that spoofs the behaviour of internet search engine Google, varying the results displayed to suit the requirements of hackers.
P2Load-A modifies the HOSTS file on infected PCs by replacing the original with a file downloaded from a remote website under the control of hackers. When users run a search, the results are normally shown correctly - but sponsored links are different. For some searches, other links appear which have been specified by the creator of this malware, resulting in increased traffic to these websites. – The Register