1. Symantec/
  2. Security Response/
  3. W32.Blebla.B.Worm

W32.Blebla.B.Worm

Risk Level 1: Very Low

Discovered:
November 30, 2000
Updated:
February 13, 2007 11:33:08 AM
Also Known As:
I-Worm.Blebla.b [KAV], W32/BleBla.b@MM [McAfee], WORM_BLEBLA.B [Trend], W32/Verona-B [Sophos], Win32.Verona.B [CA]
Type:
Worm
Systems Affected:
Windows

The worm arrives as an email message, with an HTML body and two attachments named Xromeo.exe and Xjuliet.chm. The subject of the email is randomly selected from the following set:
  • Romeo&Juliet
  • where is my juliet ?
  • where is my romeo ?
  • hi
  • last wish ???
  • lol :)
  • ,,...
  • !!!
  • newborn
  • merry christmas!
  • surprise !
  • Caution: NEW VIRUS !
  • scandal !
  • ^_^
  • Re:

This worm should run only under Windows 95/98/Me/2000 systems that have not had applied available Microsoft security updates. It does not run under Windows NT. There have been unconfirmed reports that the worm has been found on computers running Windows XP. The version of Internet Explorer that comes with this operating systems should already have all the required Microsoft security patches. If you think your Windows XP computer is infected with this worm, follow the instructions in the "Removal" section later in the writeup.

NOTES:
The HTML component in the message causes the attachments to be saved in the \Windows\Temp folder and launches the Xjuliet.chm file. Then, this file launches the Xromeo.exe file, which is the mass-mailer component of the worm.

The Xromeo.exe file attempts to terminate the HH.exe process to hide its activity. Then, the virus queries the Outlook Address Book and tries to propagate itself using several different mail servers with these IP addresses:
  • 195.117.117.6
  • 212.244.197.164
  • 195.205.96.185
  • 195.116.104.14
  • 195.117.3.111
  • 195.116.221.65
  • 212.244.67.20
  • 194.181.138.141
  • 195.205.121.183
  • 195.117.88.7
  • 212.160.95.1
  • 212.244.241.81
  • 195.205.208.33
  • 212.106.133.133
  • 195.116.72.5
  • 213.25.175.3
  • 195.117.99.98
  • 213.25.111.2

The virus has its own email engine. It connects to one of the above servers and tries to send its email message with the MIME-encoded attachments. Then, the virus alters the following registry keys to point to a file called Sysrnj.exe in the Windows directory:
  • .exe
  • .jpg
  • .jpeg
  • .jpe
  • .bmp
  • .gif
  • .avi
  • .mpg
  • .mpeg
  • .wmf
  • .wma
  • .wmv
  • .mp3
  • .mp2
  • .vqf
  • .doc
  • .xls
  • .zip
  • .rar
  • .lha
  • .arj
  • .reg

When a file with any of these extensions is launched, the worm will move the file into C:\Recycled under a random file name and replace the original file with itself, adding .exe to the suffix. For example, song.mp3 will become song.mp3.exe, and this file will be the worm. The original file is not executed.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • 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.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a 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.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. 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.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.
Writeup By: Peter Ferrie
Summary| Technical Details| Removal

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