Banks, too, need to put in similar monitoring systems to score every single activity for risk, particularly at a time when phishing, pharming and targeted Trojan attacks are becoming more common, he says.

The Trojan horse attack, in which an e-mailed attachment — like the Trojan horse of Greek myth — looks innocuous but conceals a dangerous cargo, has been an all-too-familiar part of the computer landscape for decades. In recent years, however, a new and ever more prominent feature in that landscape has been the targeted Trojan, in which the e-mail subject line or message contains language calculated to lure a particular recipient into opening the attachment. Increasingly, targeted Trojan horses are being used to steal proprietary information, obtain intelligence to get an edge on rivals, and even, it seems, obtain access to sensitive military data.

Before you run to the data center to unplug your mail server, let me assure you there are ways to fight targeted Trojan spoofing.