Trojan.Tooso.F

Risk Level 2: Low

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Discovered:: April 15, 2005
Updated:: February 13, 2007 12:37:05 PM
Also Known As:: Win32.Glieder.{T-V, Y, AA-AF} [Computer Associates], Email-Worm.Win32.Bagle.pac [Ka, Email-Worm.Win32.Bagle.{bi-bn}, W32/Bagle.br [McAfee], W32/Bagle.gen@MM [McAfee], Troj/BagleDl-N [Sophos], Troj/BagleDl-O [Sophos], TROJ_BAGLE.BH [Trend Micro]
Type:: Trojan Horse
Systems Affected:: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows XP

Trojan.Tooso.F is a Trojan horse that interferes with the operation of security software by terminating processes, stopping services, removing registry entries, and deleting files. This Trojan is similar to W32.Beagle@mm but it does not send emails.

W32.Beagle.BN@mm sends a copy of Trojan.Tooso.F as attachment.

Note: Due to increased rate of submissions, Symantec Security Response has upgraded Trojan.Tooso.F from a Category 1 to a Category 2 as of April 16, 2005.

Removing entries from the Hosts file
If this threat has modified the Windows Hosts file, there are two ways to remove these entries:

Install and run the current version of LiveUpdate. This will remove only the entries that refer to Symantec domains.
Manually edit the Hosts file and remove all the entries that the Trojan added.

To run the current version of LiveUpdate

Click download LiveUpdate.

Note: If you are not reading this Web page on the computer that is getting the error notice, the address for downloading the file is:

ftp://ftp.symantec.com/public/english_us_canada/liveupdate/lusetup.exe

If necessary, you can type this address into the address bar of the problem computer. Changes to the Hosts file will not stop you from getting to this site.
Save the file to the Windows desktop.
Double-click the lusetup.exe icon on the desktop to install LiveUpdate.
Run LiveUpdate.
Did you see the message "LU1860: LiveUpdate has detected a potential security compromise on your computer"?
- If you did, let LiveUpdate "Remove these entries from the hosts files" (Recommended).
  This should allow LiveUpdate to run.
- If you did not, that was not the cause of the problem. Return to the Removal section.

To manually edit the Hosts file and remove all the entries that the Trojan added

Note: The location of the Hosts file may vary and some computers may not have this file. For example, if the file exists in Windows 98, it will usually be in C:\Windows; and it is located in the C:\WINNT\system32\drivers\etc folder in Windows 2000. There may also be multiple copies of this file in different locations.

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:hosts
4. Click Find Now or Search Now.
5. For each Hosts file that you find, right-click the file, and then click Open With.
6. Deselect the "Always use this program to open this program" check box.
7. Scroll through the list of programs and double-click Notepad.
8. When the file opens, delete all the entries in step 11 of the "Technical Details" section.
9. Close Notepad and save your changes when prompted.
Windows XP
1. Click Start > Search.
2. Click All files and folders.
3. In the "All or part of the file name" box, type:
  
  hosts
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.
9. Click Find Now or Search Now.
10. For each Hosts file that you find, right-click the file, and then click Open With.
11. Deselect the Always use this program to open this program check box.
12. Scroll through the list of programs and double-click Notepad.
13. When the file opens, delete all the entries in step 11 of the "Technical Details" section.
14. Close Notepad and save your changes when prompted.

Antivirus Protection Dates

Initial Rapid Release version April 15, 2005
Latest Rapid Release version November 23, 2011 revision 041
Initial Daily Certified version April 15, 2005
Latest Daily Certified version November 24, 2011 revision 002
Initial Weekly Certified release date April 16, 2005

Click for a more detailed description of Rapid Release and Daily Certified virus definitions.

Threat Assessment

Wild

Wild Level: Low
Number of Infections: More than 1000
Number of Sites: More than 10
Geographical Distribution: Low
Threat Containment: Easy
Removal: Moderate

Damage

Damage Level: Medium

Distribution

Distribution Level: Medium

Writeup By: John Park

Technical Details

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Internet Security Threat Report, Volume 16