123/udp - Pentesting NTP

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Basic Information

The Network Time Protocol (NTP) ensures computers and network devices across variable-latency networks sync their clocks accurately. It's vital for maintaining precise timekeeping in IT operations, security, and logging. NTP's accuracy is essential, but it also poses security risks if not properly managed.

Summary & Security Tips:

Purpose: Syncs device clocks over networks.
Importance: Critical for security, logging, and operations.
Security Measures:
Use trusted NTP sources with authentication.
Limit NTP server network access.
Monitor synchronization for signs of tampering.

Default port: 123/udp

PORT    STATE SERVICE REASON
123/udp open  ntp     udp-response

Enumeration

ntpq -c readlist <IP_ADDRESS>
ntpq -c readvar <IP_ADDRESS>
ntpq -c peers <IP_ADDRESS>
ntpq -c associations <IP_ADDRESS>
ntpdc -c monlist <IP_ADDRESS>
ntpdc -c listpeers <IP_ADDRESS>
ntpdc -c sysinfo <IP_ADDRESS>

nmap -sU -sV --script "ntp* and (discovery or vuln) and not (dos or brute)" -p 123 <IP>

Examine configuration files

ntp.conf

NTP Amplification Attack

How NTP DDoS Attack Works

The NTP protocol, using UDP, allows for operation without the need for handshake procedures, unlike TCP. This characteristic is exploited in NTP DDoS amplification attacks. Here, attackers create packets with a fake source IP, making it seem as if the attack requests come from the victim. These packets, initially small, prompt the NTP server to respond with much larger data volumes, amplifying the attack.

The MONLIST command, despite its rare use, can report the last 600 clients connected to the NTP service. While the command itself is simple, its misuse in such attacks highlights critical security vulnerabilities.

ntpdc -n -c monlist <IP>

Shodan

ntp

HackTricks Automatic Commands

Protocol_Name: NTP    #Protocol Abbreviation if there is one.
Port_Number:  123     #Comma separated if there is more than one.
Protocol_Description: Network Time Protocol         #Protocol Abbreviation Spelled out

Entry_1:
  Name: Notes
  Description: Notes for NTP
  Note: |
    The Network Time Protocol (NTP) ensures computers and network devices across variable-latency networks sync their clocks accurately. It's vital for maintaining precise timekeeping in IT operations, security, and logging. NTP's accuracy is essential, but it also poses security risks if not properly managed.

    https://book.hacktricks.xyz/pentesting/pentesting-ntp

Entry_2:
  Name: Nmap
  Description: Enumerate NTP
  Command: nmap -sU -sV --script "ntp* and (discovery or vuln) and not (dos or brute)" -p 123 {IP}

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