Echo Service Detection

Overview

The Echo service, which runs on port 7, is a diagnostic service that echoes back any received data. While it is generally disabled by default, its presence on a system can be exploited for Denial of Service (DoS) attacks and can also be used for network scanning and reconnaissance by attackers.

• Severity: Low

Impact

• Denial of Service (DoS): Attackers can flood the Echo service with data, causing resource exhaustion.
• Network Scanning: The Echo service can be used by attackers to identify active hosts and open ports on a network.
• Information Disclosure: Unintended information might be disclosed through the Echo service if it echoes sensitive data.

Cause

• Default Configuration: The Echo service may be enabled by default on some systems, particularly older or less-secure configurations.
• Misconfiguration: Administrators may inadvertently enable the Echo service during network setup or troubleshooting.
• Lack of Awareness: Many administrators may be unaware of the potential security risks associated with running the Echo service.

Solution

1. On Linux/Unix Systems:

   • Edit the /etc/inetd.conf or /etc/xinetd.d/echo file to disable the Echo service.

     # For inetd.conf
     sudo sed -i '/echo/d' /etc/inetd.conf
     sudo service inetd restart
     
     # For xinetd
     sudo sed -i 's/disable.*/disable = yes/' /etc/xinetd.d/echo
     sudo service xinetd restart

2. On Windows Systems:

   • Use the Services management console to disable the Echo service if it is running.

     # Open Services management console
     services.msc
     
     # Locate "Simple TCP/IP Services" (this includes the Echo service)
     # Set the service to "Disabled"

Examples

Disabling Echo Service on Linux

1. Edit inetd.conf:

   sudo nano /etc/inetd.conf
   # Comment out or remove the line for echo service
   # echo    stream  tcp     nowait  root    internal
   sudo service inetd restart

2. Edit xinetd.d configuration:

   sudo nano /etc/xinetd.d/echo
   # Ensure the file contains: disable = yes
   sudo service xinetd restart

Disabling Echo Service on Windows

1. Using Services Management Console:
   • Open services.msc
   • Find the "Simple TCP/IP Services"
   • Right-click and select "Properties"
   • Set the Startup type to "Disabled"
   • Click "Stop" to stop the service if it is running

References

• CVE-1999-0635 Detail

Additional Resources

• Securing network services