Name :	Warezov.DG
Category:	Malware
Type:	Trojan-Downloader
Date of Discovery:	October 20, 2006

Warezov.DG, a variant of Warezov, is a Virus. Warezov.DG mass mails itself and collects e-mail addresses. Warezov.DG downloads files from several websites and executes them.

Automatic Disinfection

Usually standalone malware (backdoors, worms, trojans, etc.) is automatically removed by F-Secure Anti-Virus (FSAV) starting from version 5.40. Malware files get automatically renamed by FSAV, so they can not be started any more. In some rare cases, when automatic disinfection is not possible, a user can select disinfection action by him/herself to make FSAV rename or delete an infected file. In some special cases it is recommended to use specific disinfection tools provided by F-Secure. They can be downloaded from our ftp site:

ftp://ftp.f-secure.com/anti-virus/tools/

F-Secure Anti-Virus can be purchased from our webshop or from our authorised distributors. A trial version F-Secure Anti-Virus, limited to 30 days, can be downloaded from our website:

http://www.f-secure.com/download-purchase/

All the latest versions of FSAV can download anti-virus database updates automatically. However, these updates can be also downloaded and installed manually from our web or ftp sites:

http://www.f-secure.com/download-purchase/updates.shtml


Manual Disinfection

To manually disinfect standalone malware (backdoors, worms, trojans, etc.) it's usually enough to delete all infected files from a computer and to restart it. Active malware files are usually locked by operating system so different disinfection approaches are required for different operating systems.
Please note that manual disinfection is a risky process, so it is recommended only for advanced users.

If Windows 95, 98 and ME operating system is used, it is recommended to restart a computer from a bootable system diskette and to delete an infected file from command prompt. For example if a malicious file named ABC.EXE is located in Windows folder, it is usually enough to type the following command at command prompt:

DEL C:\WINDOWS\ABC.EXE

and pressing Enter. After that an infected file will be gone. If Windows NT, 2000 or XP is used, a malicious file has to be renamed with a different extension (for example .VIR) and then a system has to be restarted. After restarting, a renamed malicious file will no longer be active and it can be easy to delete manually.


Malware Disinfection Tools

F-Secure provides disinfection tools for certain malware. These tools can be downloaded from this webpage:

http://www.f-secure.com/download-purchase/tools.shtml

ftp://ftp.f-secure.com/anti-virus/tools/


Windows System Restore Issues

If Windows ME or XP is used, it is recommended to disable System Restore feature of these operating systems to prevent a computer from re-infection by an already removed malware. The fact is that System Restore feature of these operating systems might save an infected file into the special folder and copy it back to a hard drive it every time it has been renamed or deleted by F-Secure Anti-Virus or by a user. Instructions on how to disable System Restore features are here:

Windows ME:
http://www.f-secure.com/v-descs/sfc_dis.shtml

Windows XP:
http://www.f-secure.com/v-descs/sfc_dis1.shtml

It is recommended to re-enable System Restore after disinfection in order to restore a stable system configuration in the future, in case any crash or incompatibility issue occurs.


Failed Disinfection

In some cases, F-Secure Anti-Virus might not disinfect a system automatically. In this case, please visit our Support pages:

http://support.f-secure.com/enu/home/virusproblem/howtoclean/

Warezov.DG arrives on the system as attachments to spam e-mail messages. Warezov.DG attempts to downloads files from several websites and execute them.

Once Warezov.DG runs, it launches the notepad application and opens a tmp file with encrypted strings as a decoy:



It may also display the following image:




It arrives as an attachment in spammed e-mail messages. Below is an example:



Warezov.DG downloads its mass-mailing component, detected as Email-Worm.Win32.Warezov.DC, from the Internet. The Warezov.DC worm is used to mass-mail the attachement file, detected as Warezov.DG.


To ensure its execution at every system startup, Warezov.DG creates the following launch points in Windows Registry:



The malware drops the following files to a system during its installation phase:



It may arrive with the following email details:

TO:


FROM:

The From field may use any of the following format:


Note: %FirstName% may use any of the following:


%SecondName% may use any of the following:


%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 the donwloader component of the worm. It then downloads the actual worm from the Internet. It may use the following filename format:


%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%


Example:



The filename is designed to disguise the executable nature of the attachment from the recipient. 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.


Warezov.DG worm connects to the following websites in order to download more Warezov files: