The Phel Trojan horse is a new Trojan infecting computers running Microsoft's Windows XP. Phel.a attempts to exploit a vulnerability found in October in how Internet Explorer and Windows XP Service Pack 2 handle help files called from Web pages. If Phel.a successfully executes, it downloads additional code from another server including a backdoor component that can be used by the attacker to later access the infected PC remotely.

No patch is currently available. The code in Phel is currently being examined by Microsoft analysts. You can stop the Trojan with Anti-virus software or by disabling IE's Active scripting.