Linux.Backdoor.Kaiten

SUMMARY

Linux.Backdoor.Kaiten is a Trojan horse that opens a back door on the compromised computer.

Protection

• Virus Definitions (LiveUpdate™ Daily) February 14, 2006
• Virus Definitions (LiveUpdate™ Weekly) February 15, 2006
• Virus Definitions (Intelligent Updater) February 14, 2006
• Virus Definitions (LiveUpdate™ Plus) February 14, 2006

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: Medium
• Payload: Opens a back door on the compromised computer.
• Modifies Files: Modifies system files.

Distribution

• Distribution Level: Low
• Ports: TCP port 6667

TECHNICAL DETAILS

Once Linux.Backdoor.Kaiten is executed, it performs the following actions:

1. Opens a back door on the compromised computer, by using an IRC client to connect to the following IRC servers on port TCP 6667:
   
   
   • 66.119.66.107
   • irc.terra.com
   • independence.remoteserver.org
   • freedom.ns01.biz
   • networking.dyndns.org
   • liberty.no-ip.biz
   • xp.yi.org
   • 67.43.234.119
   • irc.newchrousty.org
   • Sympatico.Qc.Ca.NewChrousty.org
   • Trois-Rivieres.Qc.Ca.NewChrousty.org
   • Chat.NewChrousty.Org
   • Micro-ISP.NewChrousty.Org
   • LaLiPuS.NewChrousty.Org
   • 64.18.142.125
   • 80.188.198.35
   • irc-vod.myvnc.com
     
     
2. Joins a predetermined IRC channel and listens for commands. These commands allow a remote attacker to perform the following actions on the compromised computer:
   
   
   • Perform a distributed denial of service attack using SYN and UDP
   • Download and execute remote files
   • Change client nickname
   • Change servers
   • Send UDP packets
   • Spoof an IP addresses
   • End processes
   • Enable or disable packeting
   • Carry out flooding methods
   • End the client application
     
     
3. May modify the following system files:
   
   
   • /etc/rc.d/rc.local
   • /etc/rc.conf

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

If your Symantec antivirus product detects Linux.Backdoor.Kaiten, delete the infected files.

Once the threat attacks a computer, it is difficult to determine what else the computer has been exposed to. In most cases, changes other than those made by the threat will not have occurred. However, the author of the threat may have been able to use the threat to access the computer to make changes to it. Unless you can be absolutely sure that malicious activity has not been performed on the computer, we recommend completely reinstalling the operating system.