Keylogging Trojan uses unique attack

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An alert has been issued for a new Trojan that uses a unique method of sneaking past network administrators and corporate firewalls.

The Trojan arrives as an attachment and pretends to be an Internet Explorer Browser Helper Object (BHO). It includes keylogging software that is activated when the user visits certain web sites, typically banking and login in screens.

What makes this Trojan unique is the method it uses to send this information back. Traditionally keyloggers send back recorded information as email or HTTP POST but increasingly these types of transmissions are being watched for by security software.

Instead the Trojan encrypts its data using a XOR algorithm and then builds an Internet Control Message Protocol (ICMP) ping packet, which looks like legitimate network traffic. Internet Control Message Protocol (ICMP) ping packets are typically used to check connection speeds and deliver error messages.

"The method of network transport used by the attacker makes this Trojan unique," said internet monitoring company Websense in its alert.

"To network administrators and egress filters, this ICMP packet looks like legitimate traffic leaving the network. The attackers presumably capture this packet at their remote server, where the packet is easily decoded to reveal the information entered by the user."

The company tested the Trojan on a workstation at and tried logging onto the SSL-protected Deutsche Bank login site. The software recorded account details and passwords perfectly and sent it to a remote server.

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