BAT.Trilissa@mm

SUMMARY

Bat.Trilissa is a batch-file worm. It still performs the mass-mailing routine, but due to bug in its code, it does not include itself as an attachment.

Protection

• Virus Definitions (LiveUpdate™ Weekly) September 11, 2002
• Virus Definitions (Intelligent Updater) September 11, 2002

TECHNICAL DETAILS

When Bat.Trilissa runs, it does the following:

It drops, runs, and then deletes following files:

• %windir%AVP_Dead.vbe
• %windir%W02093029377E7837.vbe
• %windir%CAM.vbe
• %windir%Down.vbe

It also drops %windir%Basura.exe. This is not an executable file.

NOTE: %windir% is a variable. The worm locates the Windows installation folder (by default this is C:Windows or C:Winnt) and uses that as the destination.

It attempts to copy itself as:

• C:AVP BAT.bat
• C:WindowsMen■InicioProgramasI Worm AVP.bat

It deletes these files:

• C:Program FilesCommon FilesAVP Shared FilesBasesAvp.set
• C:WindowsSystemWsock32.dll

It modifies the value of

Folder C:Program FilesCommon FilesAVP Shared Files

to

Folder jodeteAVP

in the registry key

HKEY_LOCAL_MACHINESOFTWAREKasperskyLabSharedFiles

It modifies the MircScript.ini file to spread itself.

It copies AVP_Dead.vbe as the following files:

• %Temp%AVP.exe
• %windir%AVPIni.chm
• %windir%AVP_VIRUS.exe
• %windir%AVP_updater.exe
• %windir%AVP Logs.txt
• %windir%AVP_Page.exe
• %system%AVP_Consol.exe
• %system%AVP_Command.com
• %system%AVP_K
• %system%AVP_ModeStart.vbs
• %system%AVP_S
• %system%AVP.bat
• %system%Check AVP.html
• %system%Kasperky.EXE
• %system%AVP_PC.exe
• %system%AVP_SCan.exe
• %system%NAV_AVP.exe
• %system%PC-Cillin.exe
• %system%AVP_SetupStation.html
• %system%Bitdefender.exe
• %system%Panda_AntiVirus.exe
• %system%Trend_antivirus.exe

It copies itself as C:ZZ.vbs and runs it 900,000 times.

It attempts to use Microsoft Outlook to send itself. Due to a bug in the code, this is not successful. If it were, the email message would be as follows, depending on the date:

• June 1
  
  Subject: MENSAJE ESPESIAL DE MI PARTE PARA A TI!
  Message: Aniversario De Zonavirus Todo El Mundo A Celebrar!! RaZor/Zonavirus
  
• June 26
  
  Subject: AVP
  Message: I Worm AVP By RaZor/Zonavirus
  
• All other dates
  
  Subject: Nuevo Antivirus De AVP Gratis!
  Message: Andaba Por Hay Buscando Y Mira jejje Un Antivirus Nuevesito Y Bueno Es El Nuevo AVP.BAT.
  Attachments: AVP BAT.bat

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

NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Update the virus definitions.
2. Run a full system scan, and delete all files that are detected as BAT.Trilissa@mm. Delete %windir%Basura.exe and %windir%CAM.vbe.
3. If you are using AVP software, restore the value of
   
   Folder C:Program FilesCommon FilesAVP Shared Files
   
   in the key
   
   HKEY_LOCAL_MACHINESOFTWAREKasperskyLabSharedFiles

For details on how to do this, read the following instructions.

To update the virus definitions:
All virus definitions receive full quality assurance testing by Symantec Security Response before being posted to our servers. There are two ways to obtain the most recent virus definitions:

• Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
• Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.
  
  Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

To scan for and delete the infected files:

1. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
   • Norton AntiVirus consumer products: Read the document How to configure Norton AntiVirus to scan all files.
   • Symantec enterprise antivirus products: Read the document How to verify a Symantec Corporate antivirus product is set to scan All Files.
2. Run a full system scan.
3. If any files are detected as infected with BAT.Trilissa@mm, click Delete.
4. Using Windows Explorer, delete the files %windir%Basura.exe and %windir%CAM.vbe.

To restore the value in the registry:
This is necessary only if you use AVP software.

CAUTION: Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to the key
   
   HKEY_LOCAL_MACHINESOFTWAREKasperskyLabSharedFiles
   
4. In the right pane, change the Value Data of
   
   Folder
   
   to
   
   C:Program FilesCommon FilesAVP Shared Files
   
5. Exit the Registry Editor.