Rule:

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Sid:
614

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Summary:
hack-a-tack is a Trojan Horse.

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Impact:
Possible theft of data via download, upload of files, execution of files and reboot the targeted machine.

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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 hack-a-tack 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.

This Trojan is commonly used to install other Trojan programs.

The server portion opens TCP ports 31785 and 31787 and UDP ports 31789 and 31791 by default to establish a connection between client and server. The ports may then be configured by the attacker to use something other than these defaults.

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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 located at <drive>:\WINDOWS\Expl32.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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\

Registry keys added are:

	Explorer32 ="<drive>:\windows\Expl32.exe"
	Configuration Wizard = "<drive>:\windows=cfgwiz32.exe"

Removal of this entry is required.

Delete the file(s) <drive>:\WINDOWS\Expl32.exe and <drive>:\windows=cfgwiz32.exe

Ending the Trojan process is also 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>

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Additional References:

Hackfix.org
http://www.hackfix.org/miscfix/hackatack.shtml

Commodon Communications
http://www.commodon.com/threat/threat-hack.htm

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