W32.Whiter.Trojan

SUMMARY

This Trojan horse arrives appearing to be a key generator for Windows XP (Whistler).

When this Trojan is activated, it may present, in Notepad, what appears to be a valid key. This key, however, is not valid and is just a string of randomly generated numbers. At the same time, the Trojan inserts itself into the system so that next time that you start the computer, it will delete all the files from the hard disk.

Protection

• Virus Definitions (Intelligent Updater) September 24, 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: High
• Payload Trigger: The next time that the system is restarted.
• Payload: Truncates and deletes all files on the system.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

Activation
The actions of this Trojan depend on how it was configured by the hacker:

• When this Trojan is activated with the command line option -next , it runs its payload.
• When it is activated without a special command line switch, then this Trojan displays an invalid key in Notepad. If the Trojan cannot activate Notepad, it immediately runs its payload.

Insertion
The Trojan first copies itself to the %System% folder as Whismng.exe.

NOTE: %System% is a variable. The worm locates the System folder (by default this is C:WindowsSystem) and copies itself to that location

Then it adds the value

Whistler  %System%whismng.exe -next

to the registry key

HKEY_LOCAL_MACHINESOFTWAREMicrosoft
WindowsCurrentVersionRun

This causes the Trojan to run when you restart Windows.

Payload
When the Trojan runs its payload, the Trojan begins to delete files from your hard disk. When it deletes a file, it first truncates the file to zero bytes and then deletes it. This makes data recovery extremely difficult without the aid of special tools.

Before it deletes each file, the Trojan creates a file on drive C named C:wxp and writes to it the following string:

"You did a piracy, you deserve it."

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, delete any file that is detected as W32.Whiter.Trojan and remove the value that it added to the registry.

NOTE: If the payload has run, you must restore date from a recent backup and reinstall all damaged software, or contact a data recovery service. After doing so, you still must follow these removal instructions.

To remove the Trojan:

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
3. Run a full system scan.
4. Delete all files that are detected as W32.Whiter.Trojan.

To edit the registry:

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

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 the following value:
   
   Whistler  %System%whismng.exe -next
   
5. Click Registry, and then click Exit.