Discovered: April 02, 2001
Updated: February 13, 2007 11:55:17 AM
Type: Trojan Horse


This Trojan horse creates three files. The first is Trojan.Chango.htm, which is placed in the StartUp folder. The other files are Logos.sys and Logow.sys.

Antivirus Protection Dates

  • Initial Rapid Release version April 02, 2001
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version April 02, 2001
  • Latest Daily Certified version September 28, 2010 revision 036

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

Writeup By: Douglas Knowles

Discovered: April 02, 2001
Updated: February 13, 2007 11:55:17 AM
Type: Trojan Horse


Trojan.Chango.htm will display the following message when it is run:

TROJAN.Chango

First they came for the hackers. But I never did anything illegal with my computer, so I didn't speak up. Then they came for the pornographers. But I thought there was too much smut on the Internet anyway, so I didn't speak up. Then they came for the anonymous remailers. But a lot of nasty stuff gets sent from anon.penet.fi, so I didn't speak up. Then they came for the encryption users. But I could never figure out how to work PGP anyway, so I didn't speak up. Then they came for me. And by that time there was no one left to speak up.

Alara Rogers


The other two files do not contain anything but the text "Trojan.Chango."

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: Douglas Knowles

Discovered: April 02, 2001
Updated: February 13, 2007 11:55:17 AM
Type: Trojan Horse


To remove this Trojan, delete files detected as VBS.Chango, and then delete Logos.sys, Logow.sys, and Trojan.Chango.htm.

To remove this worm:

  1. Run LiveUpdate to make sure that you have the most recent virus definitions.
  2. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
  3. Delete any files detected as VBS.Chango.

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 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 file names:

    Logos.sys  Logow.sys Trojan.Chango.htm
  4. Click Find Now or Search Now.
  5. Delete the files if they are found.

(Optional) To restore copies of Logos.sys and Logow.sys:
Logow.sys and Logos.sys are used by Windows to display the Windows shutdown messages. If you delete them, then when Windows shuts down you will not see the "Windows is shutting down" or the "It is now safe to turn off your computer" messages. This does not affect the ability of Windows to shut down. If you want to restore these files, you must use the Extract command in Windows 95 or the System File Checker in Windows 98. Please see your Windows documentation for information on how to do this.

Writeup By: Douglas Knowles