Trojan.Fantibag.B

SUMMARY

Trojan.Fantibag.B is a Trojan that lowers security settings by creating filters to block access to security-related Web sites. This Trojan was downloaded from a Web site by Trojan.Tooso.L.

Protection

• Virus Definitions (LiveUpdate™ Weekly) August 17, 2005
• Virus Definitions (Intelligent Updater) August 13, 2005

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: Medium
• Payload: Blocks access to security-related Web sites.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When Trojan.Fantibag.B is executed, it performs the following actions.

1. Copies itself as %Windir%firewall_anti.exe.
   
   Note: %Windir% is a variable that refers to the Windows installation folder. By default, this is C:Windows or C:Winnt.
   
   
2. Drops the following file:
   
   %Windir%firewall_anti.exe.dll
   
   
3. Injects the .dll file into explorer.exe to disguise its actions.
   
   
4. Adds the value:
   
   "firewall_anti" = "%Windir%firewall_anti.exe"
   
   to the registry subkey:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   so that it runs every time Windows starts.
   
   
5. Blocks access to several security-related Web sites by creating both input and output filters using a list of security related domain names. A DNS Lookup is performed for each of the domain names listed. The Trojan will then create a filter for each IP address within the same class C network (255.255.255.0). The Trojan blocks the following domains and IP addresses:
   
   ftpav.ca.com
   www.pandasoftware.com
   pandasoftware.com
   clamav.net
   www.clamav.net
   www.bitdefender.com
   bitdefender.com
   ravantivirus.com
   www.ravantivirus.com
   drweb.ru
   www.drweb.com
   drweb.com
   antivir.de
   www.antivir.de
   216.200.68.152
   212.113.20.69
   63.210.193.12
   84.53.142.22
   84.53.142.6
   kaspersky.ru
   grisoft.com
   www3.ca.com
   www.viruslist.ru
   www.viruslist.com
   www.trendmicro.com
   www.symantec.com
   www.sophos.com
   www.networkassociates.com
   www.nai.com
   www.my-etrust.com
   www.mcafee.com
   www.kaspersky.ru
   www.kaspersky.com
   www.kaspersky-labs.com
   www.grisoft.com
   www.fastclick.net
   www.f-secure.com
   www.awaps.net
   www.avp.ru
   www.avp.com
   www.avp.ch
   windowsupdate.microsoft.com
   viruslist.ru
   viruslist.com
   vil.nai.com
   us.mcafee.com
   updates5.kaspersky-labs.com
   updates4.kaspersky-labs.com
   updates3.kaspersky-labs.com
   updates2.kaspersky-labs.com
   updates1.kaspersky-labs.com
   updates.symantec.com
   update.symantec.com
   trendmicro.com
   symantec.com
   support.microsoft.com
   spd.atdmt.com
   sophos.com
   service1.symantec.com
   securityresponse.symantec.com
   secure.nai.com
   rads.mcafee.com
   phx.corporate-ir.net office.microsoft.com
   networkassociates.c
   nai.co
   my-etrust.com
   msdn.microsoft.com
   media.fastclick.net
   mcafee.com
   mast.mcafee.com
   liveupdate.symantecliveupdate.com
   liveupdate.symantec.com
   kaspersky.com
   kaspersky-labs.com
   ids.kaspersky-labs.com
   go.microsoft.com
   ftp.sophos.com
   ftp.kasperskylab.ru
   ftp.f-secure.com
   ftp.downloads2.kaspersky-labs.com
   ftp.avp.ch
   fastclick.net
   f-secure.com
   engine.awaps.net
   downloads4.kaspersky-labs.com
   downloads3.kaspersky-labs.com
   downloads2.kaspersky-labs.com
   downloads1.kaspersky-labs.com
   downloads.microsoft.com
   downloads-us3.kaspersky-labs.com
   downloads-us2.kaspersky-labs.com
   downloads-us1.kaspersky-labs.com
   downloads-eu1.kaspersky-labs.com
   download.microsoft.com
   download.mcafee.com
   dispatch.mcafee.com
   customer.symantec.com
   clicks.atdmt.com
   click.atdmt.com
   www.ca.com
   ca.com
   banners.fastclick.net
   banner.fastclick.net
   awaps.net
   avp.ru
   avp.com
   avp.ch
   atdmt.com
   ar.atwola.com
   ads.fastclick.net
   ad.fastclick.net
   ad.doubleclick.net
   

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.

REMOVAL

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Disable System Restore (Windows Me/XP).
2. Update the virus definitions.
3. Run a full system scan and delete all the files detected.
4. Delete any values added to the registry.
   

For specific details on each of these steps, read the following instructions.

1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:

• How to disable or enable Windows Me System Restore
• How to turn off or turn on Windows XP System Restore

Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, reenable System Restore by following the instructions in the aforementioned documents.

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article: Antivirus Tools Cannot Clean Infected Files in the _Restore Folder (Article ID: Q263455).

2. To update the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:

• Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to Virus Definitions (LiveUpdate).
• Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted daily. You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to Virus Definitions (Intelligent Updater).
  
  The latest Intelligent Updater virus definitions can be obtained here: Intelligent Updater virus definitions. For detailed instructions read the document: How to update virus definition files using the Intelligent Updater.

3. To scan for and delete the infected files

1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
   • For Norton AntiVirus consumer products: Read the document: How to configure Norton AntiVirus to scan all files.
   • For Symantec AntiVirus Enterprise products: Read the document: How to verify that a Symantec Corporate antivirus product is set to scan all files.
2. Run a full system scan.
3. If any files are detected, click Delete.

Important: If you are unable to start your Symantec antivirus product or the product reports that it cannot delete a detected file, you may need to stop the risk from running in order to remove it. To do this, run the scan in Safe mode. For instructions, read the document, How to start the computer in Safe Mode. Once you have restarted in Safe mode, run the scan again.

After the files are deleted, restart the computer in Normal mode and proceed with the next section.

Warning messages may be displayed when the computer is restarted, since the threat may not be fully removed at this point. You can ignore these messages and click OK. These messages will not appear when the computer is restarted after the removal instructions have been fully completed. The messages displayed may be similar to the following:

Title: [FILE PATH]
Message body: Windows cannot find [FILE NAME]. Make sure you typed the name correctly, and then try again. To search for a file, click the Start button, and then click Search.


4. To delete the value from the registry
Important: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified subkeys only. For instructions refer to the document: How to make a backup of the Windows registry.

1. Click Start > Run.
2. Type regedit
3. Click OK.
   
   Note: If the registry editor fails to open the threat may have modified the registry to prevent access to the registry editor. Security Response has developed a tool to resolve this problem. Download and run this tool, and then continue with the removal.
   
   
4. Navigate to the subkey:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   
5. In the right pane, delete the value:
   
   "firewall_anti" = "%Windir%firewall_anti.exe"
   
   
6. Exit the Registry Editor.