First it was spam, then it was denial of service. Now the operators of Storm have found a new use for the botnet: phishing.

Phishers masquerading as Barclays Bank and the Halifax unit of the National Bank of Scotland are now pumping out bogus messages to unwary users, according to separate alerts issued by Fortinet and Trend Micro last night.

Many of the phishing messages were distributed from hosts known to be part of the Storm botnet. "We can only suspect that perhaps a portion of the Storm botnet is being rented out to phishers," Trend Micro said. It is the first time that researchers have traced a major phishing campaign back to Storm.

Ironically, the phishing message purports to be an "account review" from the bank that is being conducted in order to reduce fraud. Of course, clicking on the link in the email sends users to a fake site that allows phishers to steal bank account information.

The attack began as a message from Barclays, but the link to the fake Barclays site was shut down late on Monday and the same hosts began pumping out messages from Halifax on Tuesday, according to Fortinet. "This is a precursor that other banks may be targeted as well," the security vendor says.

Trend Micro warned that it detected the phishing attacks while monitoring activity on the Russian Business Network, a popular launching pad for hacking and criminal activities. This indicates that Storm and RBN are hooking up now, if they hadn't done so previously, the researchers say.

Both Fortinet and Trend Micro say they are adding the phishing sites to their lists of domains that will be blocked. However, such blocking doesn't prevent the criminals from launching attacks from other Storm hosts, sending messages purporting to be from other banks.

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