JS.TheThing.D.dr

SUMMARY

Js.TheThing.D.dr is a JavaScript that will create four files, which it will then compile to create a Backdoor Trojan.

Protection

• Virus Definitions (Intelligent Updater) November 3, 2000

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

Js.TheThing.D.dr modifies the shell=explorer.exe line of the C:WindowsSystem.ini file so that every time you start Windows Explorer, the Backdoor Trojan also runs. The following files are dropped by the Trojan:
Lcoder.hex
Onz.hex
Short.src
Test.txt

These files are then used to create
Lcoder.exe
Onz.exe
Short.com

Of these files, Onz.exe is the only viral file. The other files are used to encrypt and decrypt the file.

After creating these files, JS.TheThing.D.dr moves Onz.exe to the Windows folder and runs it. Once run, the file renames itself to Msvlrt.exe.

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 Trojan, perform these tasks (instructions follow):

• Delete as many of the Trojan files as possible.
• Edit the System.ini file
• Restart the computer, and then delete any remaining Trojan files.

To find and delete files using Windows Find or Search utility:
Because some files may be in different locations, it is easier to search for these.

1. Click Start, point to Find or Search, and click Files or Folders.
2. Make sure that "Look in" is set to (C:) and that Include subfolders is checked.
3. In the "Named" or "Search for..." box, type--or copy and paste--the following file names:
   
   oder.hex onz.hex short.src test.txt short.com Lcoder.exe onz.exe msvlrt.exe
   
4. Click Find Now or Search Now.
5. Delete the displayed files.
   
   NOTE: If you see a message that Windows cannot delete a particular file, write down the file name.

To edit the System.ini file:

1. Click Start, and click Run.
2. Type the following, and then click OK.
   
   edit c:windowssystem.ini
   
   The MS-DOS Editor opens.
   
   NOTE: If you installed Windows in a different folder, make the appropriate substitution.
   
3. In the [boot] section of the file, look for an entry similar to the following:
   
   shell=Explorer.exe msvlrt.exe
   
4. Delete the text msvlrt.exe from the line so that it reads
   
   shell=Explorer.exe
   
5. Click File, click exit, and then click Yes to save the changes.

Restart the computer. If you were unable to delete any files while following the instructions in the first section, do so now.