According to the NISCC, whose duties correspond to the U.S. Computer Emergency Readiness Team (US-CERT), more than 300 U.K. agencies and companies have been targeted by the attack, which involves more than 75 different Trojan horses and in many cases, can be traced back to the Far East.
While the attacks have been underway for some time, the NISCC said in its alert that it wanted to spread the news to "raise awareness of these attacks and provide protective advice."
The Trojans, which arrive either as attachments to e-mail messages spoofed as coming from trusted contacts, news agencies, or even government departments, or are installed after users surf to links embedded in other such messages, are after information, pure and simple.
"Trojan capabilities suggest that the covert gathering and transmitting of otherwise privileged information is a principal goal," said the alert. "The attacks normally focus on individuals who have jobs working with commercially and economically sensitive data."
NISCC's alert also said that some of the Trojans spotted were designed to avoid anti-virus scanners, and that the variety and constant evolution of the malicious code used by the attacker(s) "appears to be a strategy to identify the conditions needed to successfully penetrate a network."
That strategy is neither new nor limited to Trojans. Some analysts, in fact, believe that the ultra-prolific author(s) of the Mytob worm -- who has launched scores of variants against users -- is using the same technique to figure out the "perfect" worm.
U.K. security firm Sophos was brought in to help NISCC analyze the Trojans, said Carole Theriault, a security consultant with the company. Sophos found that in every case, the malware's goal was to install either a keylogger, or other software that would sniff through files, pull selected information, and transmit it back to the attacker.
"Who is doing this we can't answer," said Theriault, "but two-thirds of them were Trojans we've seen before. The other third were totally new, but not significantly different than your average run-of-the-mill Trojan horse."
Theriault wasn't surprised by the attack, since the number of Trojan-based assaults have been skyrocketing. According to Sophos' figures, the count of keylogging Trojans has tripled in the past 12 months.
Although the NISCC's alert leaned toward a focused, targeted attack on U.K. government workers in particular -- "Unlike phishing attacks and e-mail worms, the attackers are specifically targeting governmental and commercial organizations" -- Theriault wasn't ready to reach the same conclusion.
"From the Trojans themselves there's nothing to suggest that they're any part of a real campaign," she said. "It's possible that what the NISCC is seeing is just a lot of Trojans that hit agencies in a lot of different ways."
Another analyst, however, thought this was the best example yet of an attack profile that security experts have been expecting for a long time.
"One of the hardest thing about being in security is saying 'I told you so' without sounding smug," wrote Richard Stiennon, director of threat research at anti-spyware software vendor Webroot, in his blog Thursday.
"The attack underway in the U.K. has been predicted for years: targeted, social engineered, modified viruses used to attack government and industry," he went on. "When you think about it, this method of attack is obvious. Select a target, modify a virus or Trojan to avoid detection, and send it directly to insiders with spoofed return e-mail addresses from other insiders."