Rule:

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Sid:
208

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Summary:
Phase0 is a Trojan Horse offering the attacker control of the victim 
host. This event is generated when the victim server replies to an 
attackers client connection request.

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Impact:
Possible theft of data and control of the targeted machine leading to a
compromise of all resources the machine is connected to. This Trojan
also has the ability to delete data, steal passwords and disable the
machine.

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Detailed Information:
This Trojan affects the following operating systems:

	Windows 95
	Windows 98
	Windows ME
	Windows NT
	Windows 2000

The Trojan changes system registry settings to add the PhaseZero server
to programs normally started on boot. Due to the nature of this Trojan
it is unlikely that the attacker's client IP address has been spoofed.

The default name of the server application is MsgServ.

Server Port: 555 although this can be changed.

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Attack Scenarios:
This Trojan may be delivered to the target in a number of ways. This
event is indicative of an existing infection being activated. Initial
compromise can be in the form of a Win32 installation program that may
use the extension ".jpg" or ".bmp" when delivered via e-mail for
example.

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Ease of Attack:
This is Trojan activity, the target machine may already be compromised.
Updated virus definition files are essential in detecting this Trojan.

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False Positives:
None Known

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False Negatives:
None Known

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Corrective Action:

Edit the system registry to remove the extra keys or restore a
previously known good copy of the registry.

Affected registry keys are:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\

Registry keys added:

	MsgServ

Delete the server program msgsvr32.exe and/or ServerS.exe.

A reboot of the infected machine is recommended.

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Contributors:
Original rule writer unknown
Sourcefire Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

Dark-e
http://www.dark-e.com/archive/trojans/phase/

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