Backdoor.Kaitex

SUMMARY

Backdoor.Kaitex is a backdoor Trojan that connects to an IRC server using port 6667. It then waits for commands.

Definitions dated prior to 8/16/2001 will detect this as Backdoor.Trojan.

Protection

• Virus Definitions (Intelligent Updater) August 16, 2001

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low
• Ports: 6667

TECHNICAL DETAILS

When this Trojan is executed, it adds the value

TaskReg

to the registry key

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun

This executes the Trojan every time that Windows starts.

The Trojan then connects to IRC on port 6667, using a random user name and password. It then waits for the following commands: udp, nick, dns, get, version, kill, help, 376, 433, 422, privmsg, or ping.

What the commands do

udp	Sends UDP packets to a specified target for specified length of time
nick	Changes the nickname of victim
dns	Resolves the host to IP address
get	Retrieves a file from a specified Web site and saves it as a specified file name
version	Returns versions of the Trojan
kill	Terminates the Trojan
help	Prints a list of supported commands
376	Changes the connection mode
433	Generates a random string
422	Changes the connection mode
privmsg	Sends a private message
ping	Acknowledges the connection (returns "pong" followed by a specified acknowledgement)

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

REMOVAL

To remove this Trojan, delete all files that are detected as Backdoor.Kaitex and remove the value that it added to the registry.

To remove the Trojan:

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. Be sure that NAV is configured to scan all files.
3. Delete all files that are detected as Backdoor.Kaitex.

To edit the registry:

CAUTION: We strongly recommend that you back up the system registry before you make any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure that you modify only the keys specified. Please see the document How to back up the Windows registry before you proceed.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to the following key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoft
   WindowsCurrentVersionRun
   
4. In the right pane, delete the following value:
   
   TaskReg
   
5. Exit the Registry Editor.