Perl.Lekbot.B

SUMMARY

Perl.Lekbot.B is a worm that attempts to spread by exploiting the PHPBB Viewtopic.PHP PHP Script Injection Vulnerability (BID 10701). It opens a back door on the compromised computer and may perform a denial of service attack on third parties.

Protection

• Virus Definitions (LiveUpdate™ Daily) June 23, 2006
• Virus Definitions (LiveUpdate™ Weekly) June 28, 2006
• Virus Definitions (Intelligent Updater) June 23, 2006
• Virus Definitions (LiveUpdate™ Plus) June 23, 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 and performs denial of service attacks.

Distribution

• Distribution Level: Medium
• Target of Infection: Spreads by exploiting vulnerabilities.

TECHNICAL DETAILS

When Perl.Lekbot.B is executed, it performs the following actions:

1. Uses Google to search hosts that can be exploited by the PHPBB Viewtopic.PHP PHP Script Injection Vulnerability (BID 10701).
   
   
2. Exploits the sites, If a site is found and downloads the following file into the remote /tmp directory and run it:
   
   santogoogle.com/bot.txt
   
   
3. Attempts to change its running process name to the following process name:
   
   /usr/local/sbin/httpd -DSSL
   
   
4. Attempts to contact the following remote IRC server using port 6667:
   
   216.17.38.91
   
   
5. Allows a remote attacker to send commands to perform the following actions:
   
   
   • DDoS attack
   • Port scanning
   • IRC commands
   • Execute shell commands

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 Perl.Lekbot.B, 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.