Rule:

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Sid:
115

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Summary:
This event is generated when the victim confirms the connection request 
sent by the attacker using the NetBus Pro 2.0 trojan.

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Impact:
Possible theft of data and control of the targeted machine. This Trojan
also has the ability to scan machines and networks for open ports, it
can also redirect legitimate traffic to other destinations. It can turn
the infected host into an open proxy server.

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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 Netbus 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.

Server ports usually opened may be one of the following depending on the
version of netbus: 12345, 12346, 20034

NetBus Pro 2.0 incorporates its own protocol. It uses port 20034 by
defualt, but it can be changed by the attacker. Packet data includes a
ten byte header followed by the packet's encrypted data. The first two
bytes of the header are static: 42 4E.  The next two bytes indicate the
size of the packet, followed by two bytes for the version number,
followed by two random bytes, and the final ninth and tenth byte make up
the command code. To look for an attack from one of these functions, the
header of the suspicious packet will look like: 42 4E S1 S2 V1 V2 R1 R2 C1 C2

NOTE: S1 and S2 are size byte one and size byte two. V1 and V2 are
version number byte one and version number byte two. R1 and R2 are
random bytes one and two. C1 and C2 are the command code bytes.

The following is a list of the command codes for many of Net Bus Pro 2.0's functions:

	Capture Desktop Image: 41 01
	CDROM Open and Close: 60 01
	Client Chat: 08 00
	Execute File: 30 01
	Reading Directory Listing: 50 00
	Directory Traversal: 51 00
	Go To URL: 33 01
	Keyboard Tricks: 61 01
	Keylogger: 40 01
	Mouse Tricks: 65 01
	Open Document: 33 01
	Play Sound: 31 01
	Plugin Manager: 90 00
	Print Document: 34 01
	Record Sound: 43 01
	Redirect Application: 10 01
	Redirect Port: 00 01
	Registry Manager: 70 00
	Remote Control: 73 01 and 72 01
	Send Message: 40 00
	Send Text: 64 01
	Show Image: 32 01
	Sound System: 80 00
	System Administrator: 21 00
	System Information: 30 00
	Windows Manager: 60 00
	Any Windows Exit Function(Shutdown, Reboot, etc.): 50 01

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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:

The manual removal of this Trojan should only be attempted by an
experienced Windows system administrator.

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

Registry keys added include:

	Netbus Server Pro
	PATCH "C:\windows\patch.exe /nomsg" - note: the entry may not necessarily be called PATCH
	NetBuster = ""
	SysCopy = "command /c copy %windir%\\keyhook.dl_ %windir%\\*.dll /Y"
	Rundll32 = "rundll.dl_ /noadd"
	Rundll = "regedit /s nbsetup2.reg"

Later versions may also add one of these registry entries:

	HKEY_LOCAL_MACHINE/SOFTWARE/UltraAccess Networks/NetBus Server/
	HKEY_CURRENT_USER/NetBus Server/

These entries should be deleted.

The files rundll.dl_ (note the underscore, this is important) and
nbsetup2.reg should be deleted if they exist.

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

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Contributors:
Original Rule Writer Max Vision <vision@whitehats.com>
Sourcefire Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>
Ricky Macatee <rmacatee@sourcefire.com>

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Additional References:

Hackfix.org
http://www.hackfix.org/netbusfix/index.shtml

Dark-e Trojan Archive
http://www.dark-e.com/archive/trojans/netbus/index.html

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