Rule:

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Sid:
733

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Summary:
QAZ is a Trojan Horse.

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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.

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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

No other systems are affected. This is a windows exceutable that makes changes to the system registry.

The Trojan changes system startup files and registry settings to add the QAZ sever to programs normally started on boot.

	SID	Message
	---	-------
	108	QAZ Worm Client Login access
	731	Virus - Possible QAZ Worm (Indicates worm activity)
	775	Virus - Possible QAZ Worm Infection (Indicates worm activity)
	733	Virus - Possible QAZ Worm Calling Home (Indicates the worm is trying to send mail)

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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:

This is a particularly difficult Trojan to remove and should only be attempted by an experienced Windows 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\Current Version\Run

Registry keys added are:

	StartIE=C:\WINDOWS\notepad.exe qazwsx.hsq

This will start the Trojan each time notepad is executed.

Look for the existence of the file note.com. The file notepad.exe may have been replaced with a Trojaned version that is approximately 120 kb in size (the original is 52 kb).

A machine reboot is required to clear the existing process from running in memory.

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

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Additional References:

Whitehats arachNIDS
http://www.whitehats.com/info/IDS501
http://www.whitehats.com/info/IDS498
http://www.whitehats.com/info/IDS499

McAfee
http://vil.nai.com/vil/content/v_98775.htm

Symantec Security Response
http://securityresponse.symantec.com/avcenter/venc/data/w32.hllw.qaz.a.html

Diamond Computer Systems Security Advisory
http://www.diamondcs.com.au/web/alerts/qaz.htm

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