Name :	Email-Worm:W32/Warezov.W
Detection Names :	Email-Worm.Win32.Warezov.w
Category:	Malware
Type:	Email-Worm
Platform:	W32
Date of Discovery:	September 12, 2006

This type of worm is embedded in an e-mail attachment, and spreads using the infected computer's e-mailing networks.

Allow F-Secure Anti-Virus to disinfect the relevant files.

For more general information on disinfection, please see Removal Instructions.

Warezov.W is a mass-mailing worm that sends itself as e-mail attachments to addresses found on the infected computer.

Warezov.W also downloads another worm variant from a specified website on the Internet.


Installation

The worm shows this messagebox as a decoy during installation to a system:



During installation, the worm adds the following files to the system:


The worm also copies the file it was run from to Windows System folder.

Warezov.W modifies the Windows HOSTS file to prevent access to the following websites:


The worm also tries to stop services belonging to different firewalls and to terminate the following processes:



Payload

Warezov.W attempts to connect to the following site to download another malware file:


This file download is already detected as Email-Worm.Win32.Warezov.t. This mechanism is used to update the worm from Internet.

The worm uses rootkit features to hide its process in memory.

Additionally, the worm contacts the yuhadefunjinsa.com website to notify the worm's author. The notification is done with the POST request and it may include some additional data like the worm's version, type and so on.



Propagation

Warezov.W gathers target e-mail addresses from the Windows Address Book (WAB). It may also harvests e-mail addresses from the infected system by scanning through files with the following extension names:


The worm filters found e-mail addresses to avoid sending itself to addresses that contain any of the following substrings:



The worm sends itself as an attachment to the gathered e-mail addresses using the following e-mail format:

TO: {Gathered email address from the system}

FROM:
The from field may use any of the following format:


Where %FirstName% may use any of the following:


%SecondName% may use any of the following:


%random% uses random 4-digit characters and %domain name% may use any of the following:


Examples:


SUBJECT:
The subject may use any of the following strings:


MESSAGE BODY:
It may use any of the following messages:







ATTACHMENT:
The attachment is a copy of the worm. The filename is designed to disguise the executable nature of the attachment from the recipient.  It is created using one of the following filename formats:


%filename% may use any of the following strings:


%ext1% may use any of the following extension names:


%ext2% may use any of the following extension names:


%random% uses random numbers, for example:


This worm also uses a text file icon in its attempt to fool recipients into thinking that this file is just a normal text or log file. This is especially true when the - Hide extensions for known file types - option in Windows is enabled.