According to security experts BlackSpider Technologies, millions of emails containing the Trojan-downloader Win32.small.cfg were sent to UK businesses late on Sunday. Some 2,400,000 mails were sent before the anti-virus community could react. Win32.small.cfg was spammed out from 9pm local time on 26 January, designed to exploit the longest possible window of exposure between its release and the first anti-virus vendors issuing a patch. The infected mails were spammed with the subject "YOUR BILL PAYMENT NOT APPROVED!" containing an attached executable called BILL#5563880.