Rule:

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Sid:
146

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Summary:
This event is generated when network traffic indicating the trojan horse program Netsphere is detected.

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Impact:
Compromise of data integrity on the victim host as well as the possibility of rendering the machine temporarily unusable.

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Detailed Information:
Netsphere is a Trojan Horse offering the attacker access to the victims filesystem, instant messaging clients and some control over peripherals. This event is generated when a Netsphere server responds to an attackers client.

The Trojan changes system registry settings to add the Netsphere sever 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 Trojan also gives the attacker the ability to access the victims filesystem, turn the monitor on and off, control the mouse, access instant messaging applications and render a pentium based machine unusable.

The Trojan is also known to use TCP ports 30100, 30101 and 30102.

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Affected Systems:
Windows 95
Windows 98
Windows ME

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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.

The Trojan server is named NetSphereServer.exe.

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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_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\

Registry keys added are:

	NSSX

Removal of this entry is required.

Delete the file NetSphereServer.exe.

Ending the Trojan process is also necessary. A reboot of the infected machine is recommended.

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Contributors:
Original rule written by Max Vision <vision@whitehats.com>
Sourcefire Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

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