123/udp - Pentesting NTP
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The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks.
Default port: 123/udp
PORT STATE SERVICE REASON
123/udp open ntp udp-response
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>
- ntp.conf
NTP protocol by design uses UDP to operate, which does not require any handshake like TCP, thus no record of the request. So, NTP DDoS amplification attack begins when an attacker crafts packets with a spoofed source IP to make the packets appear to be coming from the intended target and sends them to NTP server. Attacker initially crafts the packet of few bytes, but NTP responds with a large amount of data thus adding to amplification of this attack.
MONLIST command: It is a NTP protocol command which has very little use, but it is this command which is the main culprit for this attack. However, the use of MONLIST command is to give details of the last 600 clients that have connected to the NTP time service. Below is the command syntax:
ntpdc -n -c monlist <IP>
ntp
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) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks.
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}
HackenProof is home to all crypto bug bounties.
Get rewarded without delays
HackenProof bounties launch only when their customers deposit the reward budget. You'll get the reward after the bug is verified.
Get experience in web3 pentesting
Blockchain protocols and smart contracts are the new Internet! Master web3 security at its rising days.
Become the web3 hacker legend
Gain reputation points with each verified bug and conquer the top of the weekly leaderboard.
- Do you work in a cybersecurity company? Do you want to see your company advertised in HackTricks? or do you want to have access to the latest version of the PEASS or download HackTricks in PDF? Check the SUBSCRIPTION PLANS!