JS.Blink.A@m

SUMMARY

JS.Blink.A@m is a JScript encrypted worm, which spreads using mIRC and PIRCH.

Protection

• Virus Definitions (Intelligent Updater) May 9, 2001

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

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When executed, the worm does the following:

1. It copies itself as 3Nokia.js to the Windows folder.
2. It drops the decryptor Debug.vbs into the WindowsSystem folder and runs it; this decrypts and executes the worm. Debug.vbs then quits.

When the decrypted version of JS.Blink.A@m is executed by the decryptor, it does the following:

1. If the worm finds mIRC, it modifies the Script.ini file. This causes the infected computer to send the worm to other users over the IRC network.
2. If it finds PIRCH, it modifies the Events.ini file. This allows the worm to replicate through PIRCH. The modified Script.ini and Events.ini files are detected as JS.Blink.A@m.
3. The worm drops the SYST.cOm.scf (Windows Explorer Command format) file and the Runner.ini.vbs Trojan into the Windows folder.
4. It creates the value
   
   Blink C:WindowsRunner.ini.vbs
   
   in the registry key
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   to enable the Trojan to run at startup.
   
5. It then runs the Runner.ini.vbs Trojan. The Trojan causes Windows to blink every 1 second by minimizing and then restoring all windows.
6. JS.Blink.A@m drops the file Phone.htm into the Windows folder and sets it as the default Windows wallpaper. The page is not infected. It contains a mobile phone image only.
7. The worm next drops the Runner.inf file and runs the Debug.exe utility to drop the Phone.jpg image file into the Windows folder.
8. Next, JS.Blink.A@m drops the Phone.vbs Trojan into the Windows folder. Phone.vbs is designed to run the Dialer.exe program and make it dial random phone numbers.
9. Finally, it creates the value
   
   Dial WindowsSystemPhone.vbs
   
   in the registry key
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   to enable the Trojan to run at startup.

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

To remove this worm, delete files detected as JS.Blink.A@m, and undo the changes that the worm made to the registry.

To remove the worm:
This will remove all the viral files that were dropped.

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
3. Delete any files detected as JS.Blink.A@m.

To edit the registry:

CAUTION: We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure you modify only the keys specified. Please see the document How to back up the Windows registry before proceeding.

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 following key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoft
   WindowsCurrentVersionRun
   
4. In the right pane, delete these values:
   
   Blink
   Dial
   
5. Exit the Registry Editor.

Restore the default wallpaper according to your preference.