Linux.Plupii.C

SUMMARY

Linux.Plupii.C is a worm with back door capabilities that spreads by exploiting vulnerabilities.

Protection

• Virus Definitions (LiveUpdate™ Daily) February 19, 2006
• Virus Definitions (LiveUpdate™ Weekly) February 22, 2006
• Virus Definitions (Intelligent Updater) February 19, 2006
• Virus Definitions (LiveUpdate™ Plus) February 19, 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 multiple back doors on the compromised computer.

Distribution

• Distribution Level: Medium
• Ports: UDP port 27015; TCP port 8080

TECHNICAL DETAILS

When Linux.Plupii.C is executed, it performs the following actions:

1. Opens a back door on UDP port 27015, which enables a remote attacker to have unauthorized access to the compromised computer.
   
   
2. Generates IP addresses and uses them to build URLs which include the following strings:
   
   
   • /cvs/
   • /articles/mambo/
   • /cvs/mambo/
   • /blog/xmlrpc.php
   • /blog/xmlsrv/xmlrpc.php
   • /blogs/xmlsrv/xmlrpc.php
   • /drupal/xmlrpc.php
   • /phpgroupware/xmlrpc.php
   • /wordpress/xmlrpc.php
   • /xmlrpc/xmlrpc.php
     
     
3. Sends HTTP requests to the URLs it generates, and attempts to spread by exploiting the following Web server-related vulnerabilities:
   
   
   • The XML-RPC for PHP Remote Code Injection vulnerability (as described in Bugtraq ID 14088)
   • The AWStats Rawlog Plugin Logfile Parameter Input Validation Vulnerability (as described in Bugtraq ID 10950)
   • The Darryl Burgdorf Webhints Remote Command Execution Vulnerability (as described in Bugtraq ID 13930)
     
     
4. When the worm finds a vulnerable script on the compromised computer, it downloads and executes a malicious install script from the following Web site:
   
   [http://]198.170.105.69/[REMOVED]
   
   
5. Attempts to download the following files to the /tmp/.temp folder:
   
   
   • cb (Detected as Linux.Plupii.B)
   • https (A Perl script with IRC back door functionality.)
   • ping.txt (A Perl script that is a reverse shell back door.)
   • httpd
     
     
6. Attempts to connect to a predetermined IP address on TCP port 8080 and open a shell back door.
   
   
7. Opens an IRC back door, which attempts to connect to one of the following IRC servers:
   
   
   • eu.undernet.org
   • us.undernet.org
   • 195.204.1.130
   • 194.109.20.90
     
     The worm joins a channel that contains the following string and waits for commands from a remote attacker:
     
     lametrapchan

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.Plupii.C, 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.