Rule:

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Sid:
1985

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Summary:
Doly 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. This Trojan also has the ability to delete data, steal passwords and disable the machine. Later versions are capable of launching DDoS attacks.

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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, Win.ini and System.ini. When first executed the Trojan replicates itself and in most cases, gives the copy a random name. This Trojan may use the file extensions ".exe" or ".dll".

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

	SID	Message
	---	-------
	119	Doly 2.0 access (outgoing TCP connection)
	1985	Doly 1.5 server response (outgoing TCP connection)

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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_CLASSES_ROOT\exefile\shell\open\command
	HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Current Version\Run
	HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Current Version\RunServices
	HKEY_LOCAL_MACHINE\Hardware\Data
	HKEY_LOCAL_MACHINE\Hardware\Enum
	HKEY_LOCAL_MACHINE\Software\Microsoft\DirectXMedia

Registry keys added are:

	HKEY_CLASSES_ROOT\.dl

Removal of the replicant is also required, look for files ending in ".exe" or ".dll" in the <drive>:\Windows\ or <drive>:\Windows\System\ folders that use alphanumeric file names. The name of the replicant may be in one of the registry keys above.

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

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Contributors:
Sourcefire Research Team
Brian Caswell <bmc@sourcefire.com>
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

Whitehats arachNIDS
http://www.whitehats.com/info/IDS312

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

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

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