UK businesses faced a barrage of 115,000 emails containing a new Trojan on Friday, 22 January before anti-virus vendors scrambled out an update, according to email filtering firm BlackSpider Technologies.

The Trojan downloader malware - called Agent-ADO - comes in the payload to a message that poses as a warning about a user's credit card limits been exceeded.

BlackSpider detected the malware at 0910GMT, 20 January. But it was three-and-a-half hours before the first anti-virus vendor used by BlackSpider issued a patch, once again illustrating the shortcomings of conventional ant-virus scanners in fighting fast-moving virus outbreaks.

Infected emails commonly have the subject line "ERROR:YOUR CREDIT CARD OVERDRAFT EXCEED!" and an infected attachment, a packed executable file called FILE1185 which is 5592 bytes long. Analysis of the malware is ongoing. Sysadmins are encouraged to set up rules to block the malware at the gateway. The rest of you: resist the temptation to open the attachments of unsolicited emails.

Virus writers commonly use networks of compromised PCs to seed infection over a short space of time but the ferocity of the latest attack is unusual. ®

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