GEN:SID 1:162
Message BACKDOOR Matrix 2.0 Server access
Summary Matrix is a Trojan Horse offering the attacker the ability to upload
files to, and download files from the victim host.
Impact Possible theft of data and control of the targeted machine leading to a
compromise of all resources the machine is connected to.
Detailed Information This Trojan affects the following operating systems:

    Windows 95
    Windows 98
    Windows ME
    Windows NT
    Windows 2000
    Windows XP

The Trojan changes system registry settings to add the Matrix 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.

Matrix is based on the Girlfriend Trojan, see sid 145.

The default name of the server application is Wincfg.exe
Affected Systems  
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.
Ease of Attack This is Trojan activity, the target machine may already be compromised.
Updated virus definition files are essential in detecting this Trojan.
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

Wincfg.exe ="<DRIVE>:\WINDOWS\Wincfg.exe"

A reboot of the infected machine is recommended.
Additional References Whitehats arachNIDS
http://www.whitehats.com/info/IDS83
Rule References arachnids: 83