Backdoor.NetDevil

When Backdoor.NetDevil runs, it does the following:

It copies itself to the %System% folder. The file name that it uses may vary, because the hacker who creates this backdoor Trojan can choose any desired file name.

NOTE: %System% is a variable. The Trojan locates the \Windows\System folder (by default this is C:\Windows\System or C:\Winnt\System32) and copies itself to that location.

It adds a value that refers to the dropped file to one of the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\Run
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\RunServices

When the hacker creates the BackDoor.NetDevil server file, there are many functions that can be added. For example, the file can be programmed to:

• Display a fake error message to conceal its true nature.
• Choose the ports that are used by the backdoor to communicate with the hacker. By default, it uses port 901 for direct control, port 902 for communicating logged keystrokes, and port 903 for file transfer.
• Use different notification methods to send information to the hacker about the compromised computer.
• Attempt to kill running firewall and antivirus processes.

When Backdoor.NetDevil runs, it allows the hacker to remotely take control over the compromised computer. This allows the hacker to

• Obtain full control of the file system
• Upload files to and download files from the host computer
• Run files of the hacker's choice
• Kill running processes
• Display messages
• View the contents of the screen
• Log keystrokes
• Perform annoying actions, such as manipulating the mouse, opening and closing the CD-ROM drive, turning the monitor on and off, and so on.

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