New Trojan appeared to attack Internet Explorer

Microsoft's warning on November 30 said that Windows users can lose control of the system if they only access a Web site that stores "malicious" code.

Security flaws in Internet Explorer (IE) are being exploited by a dangerous type of Trojan, "TrojanDownloader: Win32 / Delf.DH". The name of this Trojan has been added to the alert list sent to all Microsoft customers.

Microsoft said the exploit was discovered and warned in May 2005. Security experts initially said the flaw could help hackers perform DoS attacks (denial of service attacks), crippling IE; and recently added another dangerous ability discovered, which is to allow remote "malicious" code execution.

The vulnerability affects Windows 98, Windows ME, Windows 2000 and Windows XP operating systems. An attacker can take control of the system by putting a malicious code on a website and enticing users to access it.

There is no fix for the vulnerability yet, and Microsoft recommends that users need to disable Active Scripting in IE.