Threat Explorer

The Threat Explorer is a comprehensive resource consumers can turn to for daily, accurate, up-to-date information on the latest threats, risks and vulnerabilities.

VBS.Infi

VBS.Infi

Discovered:
26 March 2002
Updated:
13 February 2007
Systems Affected:
Windows

VBS.Infi is a Trojan Horse program that tries to take up disk space on every drive, including network drives, by making multiple copies of large files. This Trojan does not spread by itself, but may be sent as an email attachment, or may be spread by other means.

Antivirus Protection Dates

  • Initial Rapid Release version 26 March 2002
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 26 March 2002
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date 27 March 2002
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When VBS.Infi is executed, it checks every available drive starting with the current working folder and recursively processes subdirectories, by searching for files with the following extensions:
  • .html
  • .jpg
  • .bmp
  • .exe
  • .com.
  • .dat
  • .mp3
  • .avi

For each such file that VBS.Infi finds, it makes 31 copies in the same folder as the original file.

For example, the file, C:\Windows\Notepad.exe, will be copied to:
  • C:\Windows\Notepad.exe0
  • C:\Windows\Notepad.exe1

and so on, up through C:\Windows\Notepad.exe30.

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.

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
  1. Update the virus definitions.
  2. Run a full system scan and delete all the files detected as VBS.Infi.
  3. Delete the files that VBS.Infi added.
For specific details on each of these steps, read the following instructions.

1. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
  • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).

    The 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.

2. Scanning for and deleting the infected files
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
  2. Run a full system scan.
  3. If any files are detected as infected with VBS.Infi, click Delete.

3. Deleting the files
This step is only necessary if the script has been run.

To determine whether the script created any extra files on your computer:
  1. Start Windows Explorer.
  2. Click the View menu (Windows 95/98/NT) or the Tools menu (Windows Me/2000/XP), and then click Options or "Folder options."
  3. Click the View tab.
  4. Uncheck "Hide file extensions for known file types."
  5. Do one of the following:
    • Windows 95/NT: Click "Show all files."
    • Windows 98: In the Advanced settings box, under the "Hidden files" folder, click Show all files.
    • Windows Me/2000/XP: Uncheck "Hide protected operating system files," and under the "Hidden files" folder, click "Show hidden files and folders."
  6. Click Yes if you see a Warning dialog box.
  7. Click Apply, and then click OK.
  8. Follow the instructions for your operating system.
    Windows 95/98/Me/NT/2000
    1. Click Start, point to Find or Search, and then 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:

      *.exe0 *.exe1 *.exe2

      NOTE: Make sure that you type a space between the two sets of text.

    4. Click Find Now or Search Now. If the search results show multiple copies of files that have the same filename, but with 0, 1, and 2 appended to the extension, it is likely that the script has run. Manually delete the files using Windows Explorer, or restore your system from a backup. Refer to the "Technical Details" section for details on other file extensions that may have been copied.

    Windows XP
    1. Click Start, and then click Search.
    2. Click All files and folders.
    3. In the "All or part of the file name" box, type, or copy and paste, the following:

      *.exe0 *.exe1 *.exe2

      NOTE: Make sure that you type a space between the two sets of text.

    4. Verify that "Look in" is set to "Local Hard Drives" or to (C:).
    5. Click "More advanced options."
    6. Check "Search system folders."
    7. Check "Search subfolders."
    8. Click Search. If the search results show multiple copies of files that have the same filename, but with 0, 1, and 2 appended to the extension, it is likely that the script has run. Manually delete the files using Windows Explorer, or restore your system from a backup. Refer to the "Technical Details" section for details on other file extensions that may have been copied.

Writeup By: Heather Shannon