DonaldD.Trojan

The server application may be configured with several different options.
The networking protocol may be TCP or SPX. Any port number between 1 and 65535 may be selected for communication. The default port number for TCP is 23476, and an additional default port is 23477. For SPX, it is 0x9014 and an additional default port is 0x9015.

A password may be specified to limit the access on a server. However, there is a bug in version 1.52 of the Trojan. In the client GUI, the password typed in is initially hashed using MD5 and is converted to a 32-byte string, which is the hex representation. Then the result is sent to the server. For the command-line version of the client, the password is sent without using any type of encryption. Thus, if a user sets the password of the server using the command-line client, then they cannot access it again by using the GUI client with the same password.

Additional bugs found in version 1.52 of this Trojan:

• When the client attempts to play a .wav file to the server, and the client does not specify a file name in this field, the client program crashes.
• The same situation occurs when the client user forgets to specify the path for the server upgrade command.

The following is a list of commands the client program may send to the server program:

• Create and delete directories
• Copy, delete, rename, upload, and download files
• View, terminate, and set priorities for processes
• Suspend and resume threads
• Execute programs
• Create and delete registry keys
• Set registry values
• Modify system date and time
• Perform a shutdown, logoff, restart, and power-off
• Obtain a list of windows opened
• Get a snapshot of the entire screen or just for a specific window
• Send messages to a specific window
• Modify CMOS (this currently works only in Windows 95/98)
• Look at the contents of the buffer where the keyboard input is stored
• Remap and disable keys of the keyboard
• Simulate certain keystrokes (only works in Windows 95/98)
• Open and close the CD-ROM tray
• Turn the monitor on and off
• Send message boxes with a few sets of buttons to choose from
• Play .wav files
• Chat with other people
• Obtain CMOS and screen saver passwords
• Query a list of shared resources

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.

Summary