The financial sector has been identified as the most attacked by hackers in an annual review of hacking activity by security firm Counterpane and email management company MessageLabs.

The finance and banking sectors picked up nearly 40 per cent of all Trojan attacks last year, and manufacturing was the next worst affected at 22 per cent.

"Hackers are starting to deploy tactics that bypass stronger authentication schemes," said Alex Shipp, senior antivirus technologist at MessageLabs.

"The new Trojan programs do not have to trick victims into revealing their password. Instead, they wait for the victim to perform their normal banking business. While the victim checks their balance, the Trojan silently siphons money out of the account."

However, the most common target for spyware was the pharmaceuticals sector, which received nearly half of all spyware infections. The insurance industry was the second most targeted sector.

"Today's attackers are smarter and stealthier," warned Bruce Schneier, founder and chief technology officer at Counterpane.

"They are much more likely to install spyware, as they are more interested in making money.

"These attackers will continue to exploit enterprise networks for their own purposes, and it is essential that organisations keep their security vigilant to counter these threats."

The survey also revealed details about the most common methods of attack. One of the simplest is disguising a virus as a Word document and sending it in as a job application.

These kinds of attacks were highlighted by reformed hacker Kevin Mitnick in his book The Art of Deception.