Name :	Worm:W32/Gurong.A
Detection Names :	Email-Worm.Win32.Gurong.a
Category:	Malware
Type:	Worm
Type:	Email-Worm
Platform:	W32
Origin:	RUSSIAN FEDERATION
Date of Discovery:	March 21, 2006

A standalone malicious program which uses computer or network resources to make complete copies of itself. May include code or other malware to damage both the system and the network.

Rootkit Detection with Blacklight

If the rootkit is not detected or it is hidden so that FSAV cannot detect its file, it is still possible to detect the malicious activity by scanning the system with a generic rootkit scanner, such as F-Secure BlackLight.

Registry Modifications
Creates these keys:

Worm:W32/Gurong.A worm in e-mails and in Kazaa shared folders. It has a rootkit functionality.

This worm appeared on the 21st of March 2006.


Installation

After the worm's file is run, it copies itself to the Windows System folder as wmedia16.exe and creates a startup key value for this file in the registry.


Rootkit

The worm is able to hide the following items:


When the worm is active, it hides its own process, file and launch point in the registry.

The worm installs a call gate through \Device\PhysicalMemory to execute part of its code in kernel mode (ring 0). The kernel-mode code replaces the following function pointers from the system service table:


This allows it to hide files, registry keys and values. In addition, the worm is able to modify kernel-mode process structures to hide any process it specifies.


Propagation (E-mail)

Before spreading, the worm looks for e-mail addresses in the victim's Windows Address Book (WAB) file and also in files with the following extensions:


The worm ignores e-mail addresses that contains any of the following substrings:


The worm then constructs the e-mail message used to deliver the worm's file by using the following "building blocks". The subject of the message can be one of the following:



The body text can be one of the following:


The infected attachment name can be any of the following:


Infected attachments can have the following extensions:


The worm spoofs (fakes) the sender's e-mail address. The following user names are used to compose the fake sender's address:


The following domain names are used to compose the fake sender's address:



Propagation (File sharing)

The worm copies itself to the shared folder of the peer-to-peer Kazaa client, with the following names:


The extensions of the copied files are randomly selected from the following variants:



Detection

F-Secure Anti-Virus detects this malware with the following update: