An ingenious new trojan is hijacking PCs to send SMS-based spam to mobile phones.
After a PC has been infected, the Delf-HA trojan contacts a website for details on which spam campaign to run and then randomly generates a series of Russian mobile numbers beginning with the prefix +7921 or +7911. It uses the send e-mail function of a number of Russian mobile network websites to deliver the mail sent from the infected machines.
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That many of the mobile numbers will not have been allocated to customers is of no consequence as enough real ones can be targeted randomly. The contents of the spam are thought to vary but one message shown to Techworld promoted the download of MP3 music files from a named Russian website.
Although Delf-HA targets only Russian mobile networks, experts have warned that the same technique could be used to send spam to subscribers of networks in other countries.
"Now SMS spammers are taking a leaf out of the book of e-mail spammers, and using unprotected innocent PCs to pass on their unwanted messages," said Graham Cluley of antivirus supplier Sophos.
Spam is not a new phenomenon on mobiles but volumes remain low compared with PC-based e-mail. Delf-HA could signal a depressing turning point.
To date, most of the concern has centred around the possibility of viruses such as Cabir infecting mobiles themselves. Nokia also announced in the summer that it would offer antivirus software for its 6670 smartphone.
John Dunn writes for Techworld