A malicious Trojan horse is spreading over the internet as an update to Skype. The code is delivered through e-mail.

MessageLab, an e-mail security firm, warned yesterday about this malicious Trojan, which is a variant of IRCbot and which is delivered with an e-mail that pretends to be an update to Skype. After the infection, the users gets prompted with an error message. All access to security updates is blocked an a back door is installed on the machine.

The e-mail can have one different subjects but all refers to Skype. For example: “Skype for Windows 1.4 – Have you got the new Skype?” In the e-mail body there is an advertisement about Skype which advises the user to run the attached file to find out more, as MessageLabs announced.

MessageLabs has intercepted 150 copies of the e-mail since Sunday. The “cybercriminals” are using all kinds of methods to make their victims to fall in their trap. From masking their malicious code with porn images, security updates to messages from system administrators and news photos this tactic is new and specialists say that it will be used in the future. So we have to be extremely carefully with our e-mail.