TROJ_AGENT.ACTH is the latest threat discovered by security company Trend Micro which might come as a DLL file aiming to infect your computer. In a security advisory published today, the vendor reported that the Trojan horse affects Windows 98, ME, NT, 2000, XP and Server 2003, having an overall risk rating set too low. Sophos, another important name in the security industry, discovered the threat as Mal/Behav-119, the company saying that "Mal/Behav-119 is a family of malicious downloaders for the Windows platform." Trend Micro informed the Trojan might be deployed by other malware files but it can be also downloaded as a standalone infection without users' approval. The entire infection process is started once the user loads a dangerous website "equipped" with TROJ_AGENT.ACTH.

"This Trojan may be dropped by other malware. It may be downloaded unknowingly by a user when visiting malicious Web site(s). It may arrive as a .DLL file that exports functions used by other malware. It is used by other malware to drop the component file AUTORUN.INF," Trend Micro wrote in the security notification published today.

Although it has a low distribution potential, no less than 24 Asian computers already confirmed the infection with TROJ_AGENT.ACTH even if the Trojan was first discovered one day ago.

The infection removal is pretty easy to do because most antiviruses were already updated with protection against the Trojan. However, Trend Micro recommends extra care when removing the malicious file from your computer.

"This malware is a .DLL file that may come with a main component detected by Trend Micro as another malware. It may also be used by several variants of a certain malware family. If your Trend Micro product detects another malware on your system, refer to the manual removal instructions of that detected malware," the security advisory also reads.