W32.STD.D

SUMMARY

W32.STD.D attempts to send a copy of itself to other mIRC users. Two variants of W32.STD.D have been found. Both Trojans have bugs and do not spread through mIRC. This threat is written in the Microsoft Visual Basic programming language.

W32.STD.D deletes .dat files in the C:Program FilesNorton AntiVirus folder.

Protection

• Virus Definitions (LiveUpdate™ Weekly) October 30, 2002
• Virus Definitions (Intelligent Updater) October 30, 2002

Threat Assessment

Wild

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

Damage

• Damage Level: Low
• Deletes Files: deletes all .dat files in C:program filesNorton Antivirus folder.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When W32.HLLP.STD.D runs, it does the following:

It displays one of these windows, depending on the variant:



or



It creates the following files:

• C:WindowsSystemSystray_.exe
• C:WindowsSystemRuntray_.dll

NOTE: The files can be created successfully only if the folder C:WindowsSystem exists. In tests performed by Symantec Security Response, due to bugs in the code, those two files are either zero bytes in length or they are corrupted. As such, they pose no threat.

It modifies the default value in the registry key

HKEY_LOCAL_MACHINESoftwareCLASSESexefileshellopencommand

to

[Default] "C:WindowsSystemsystray_.exe" %1 %*

NOTE: Because the Trojan does not successfully copy itself to C:WindowsSystemSystray_.exe, an error message is displayed when running executable files.

The Trojan adds the value

SystemTray C:Windowssystemsystray_.exe

to the registry key

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun

If it does not already exist, the Trojan creates the registry key

HKEY_LOCAL_MACHINESoftwareMcAfee

It then creates the subkey Scan95 in this key, and adds the following values:

bVShieldEnabled dword:00000000
CurrentVersionNumber 666
DAT NONE
DATFile -2000
die bit<remove 2 letters> created by $$$$$ MOELLER
VirusInfoURL http:/ /www.norton.com

or

bVShieldEnabled dword:00000000
CurrentVersionNumber 666
DAT NONE
DATFile -2000
die bit<remove 2 letters> created by Moeller_Virus
VirusInfoURL http:/ /yourinfected.com

If the C:Mirc folder exists, the Trojan creates the C:MircScript.ini file. It attempts to use this script to spread itself to other mIRC users. The file name is Install_show.exe.

It deletes all .dat files in the folder C:Program FilesNorton AntiVirus.

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. Reverse the changes that the worm made to the registry.
2. Update the virus definitions.
3. Run a full system scan, and delete all files that are detected as W32.STD.D.
   

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

To reverse the changes that the worm made to the registry:

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.

Because the worm modified the registry so that you cannot run .exe files, you must first make a copy of the Registry Editor as a file with the .com extension, and then run that file.

1. Do one of the following, depending on which version of Windows you are running:
   • Windows 95/98 users: Click Start, point to Programs, and click MS-DOS Prompt. A DOS window opens at the C:Windows prompt. Go on to step 2 of this section.
   • Windows Me users: Click Start, point to Programs, point to Accessories, and then click MS-DOS Prompt. A DOS window opens at the C:Windows prompt. Go on to step 2 of this section.
   • Windows NT/2000 users:
     1. Click Start, and click Run.
     2. Type the following and then press Enter:
        
        command
        
        A DOS window opens.
        
     3. Type the following, and then press Enter:
        
        cd winnt
        
     4. Go on to step 2 of this section.
   • Windows XP:
     1. Click Start, and click Run.
     2. Type the following, and then press Enter:
        
        command
        
        A DOS window opens.
        
     3. Type the following, and then press Enter after typing each one:
        
        cd
        cd windows
        
     4. Proceed to step 2 of this section.
        
2. Type the following, and then press Enter:
   
   copy regedit.exe regedit.com
   
3. Type the following, and then press Enter:
   
   start regedit.com
   
   The Registry Editor will open in front of the DOS window. After you finish editing the registry, exit the Registry Editor, and then also exit the DOS window.
   
4. Navigate to and select the following key:
   
   HKEY_LOCAL_MACHINESoftwareClassesexefileshellopencommand
   
   CAUTION: The HKEY_LOCAL_MACHINESoftwareClasses key contains many subkey entries that refer to other file extensions. One of these file extensions is .exe. Changing this extension can prevent files that end with an .exe extension from running. Make sure that you browse all the way along this path until you reach the command subkey.
   
   Make sure that you modify the HKEY_LOCAL_MACHINESoftwareClassesexefileshellopencommand subkey that is shown in the following figure:
   
   <<=== NOTE: Modify this key.
   
5. In the right pane, double-click the (Default) value.
6. Delete the current value data, and then type: "%1" %* (That is, type the following characters: quote-percent-one-quote-space-percent-asterisk.)
   
   NOTES:
   • Under Windows 95/98/Me/NT, the Registry Editor automatically encloses the value within quotation marks. When you click OK, the (Default) value should look exactly like this:
     
     ""%1" %*"  
     
   • Under Windows 2000/XP, the additional quotation marks will not appear. When you click OK, the (Default) value should look exactly like this:
     
     "%1" %*
     
   • Make sure that you delete completely all value data in the command key before you type the correct data. If you leave a space at the beginning of the entry, any attempt to run program files will result in the error message "Windows cannot find .exe." If you see this message, start over at the beginning of this document, and make sure that you completely remove the current value data.
     
7. Navigate to and select the key
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
8. In the right pane, delete the value
   
   SystemTray C:Windowssystemsystray_.exe
   
9. Navigate to and select the key
   
   HKEY_LOCAL_MACHINESoftwareMcAfeeScan95
   
10. In the right pane, delete these values if they exist
    
    bVShieldEnabled dword:00000000
    CurrentVersionNumber 666
    DAT NONE
    DATFile -2000
    die bit<remove 2 letters> created by $$$$$ MOELLER
    VirusInfoURL http:/ /www.norton.com
    die bit<remove 2 letters> created by Moeller_Virus
    VirusInfoURL http:/ /yourinfected.com
    
11. Exit the Registry Editor.

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 W32.STD.D, click Delete.