Symantec Security Response is investigating a highly infectious email trojan horse to cause a massive trojan surge. This is the largest widespread Internet attack in the recent months.

Symantec Security Response team monitors the Trojan.Peacomm malicious code first identified in Jan 2007.

The nature of this email spam surge changes over time and the latest attack reports show that the attackers network is trying to compromise the security of unprotected computers on a global scale.

The malicious software has been identified to arrive as an email attachment pretending to be a legitimate security update notification.

Opening the attachment is extremely dangerous and the computers affected are likely to be used to distribute spam thorough the Internet infecting other computers.

Due to the evolving nature of this trojan horse the subject lines and/or attachment filenames may change in time. Users are advised to not open emails such as these.

The attachment itself contains an infected file that will install the trojan horse on the system as a system driver and will attempt to fetch malicious software the Internet.

The file in question will be identified as Trojan.Packed.13 that will create Trojan.Peacomm upon execution. Symantec Security Response advises all Internet users to handle unsolicited emails with care and not to open any email attachments that claim to be legitimate or interesting.

This technique has been used by threat writers for many years and, unfortunately, is often successful against unprotected users. Using encouraging, attentive subjects or attachment names is a common attackers' technique to make unaware users to open infected email messages.