Port Scanning

Scanners and most other auxiliary modules use the ‘RHOSTS’ option instead of ‘RHOST’. RHOSTS can take IP ranges (192.168.1.20-192.168.1.30), CIDR ranges (192.168.1.0/24), multiple ranges separated by commas (192.168.1.0/24, 192.168.3.0/24), and line-separated host list files (file:/tmp/hostlist.txt). This is another use for a grepable Nmap output file.

By default, all of the scanner modules will have the ‘THREADS’ value set to ‘1’. The ‘THREADS’ value sets the number of concurrent threads to use while scanning. Set this value to a higher number in order to speed up your scans or keep it lower in order to reduce network traffic but be sure to adhere to the following guidelines:

• Keep the THREADS value under 16 on native Win32 systems
• Keep THREADS under 200 when running MSF under Cygwin
• On Unix-like operating systems, THREADS can be set as high as 256.

We can use the db_nmap command to run Nmap against our targets and our scan results would than be stored automatically in our database. However, if you also wish to import the scan results into another application or framework later on, you will likely want to export the scan results in XML format. It is always nice to have all three Nmap outputs (xml, grepable, and normal). So we can run the Nmap scan using the -oA flag followed by the desired filename to generate the three output files, then issue the db_import command to populate the Metasploit database.

Run Nmap with the options you would normally use from the command line. If we wished for our scan to be saved to our database, we would omit the output flag and use db_nmap. The example below would then be db_nmap -v -sV 192.168.1.0/24.

msf > nmap -v -sV 192.168.1.0/24 -oA subnet_1
[*] exec: nmap -v -sV 192.168.1.0/24 -oA subnet_1

Starting Nmap 5.00 ( http://nmap.org ) at 2009-08-13 19:29 MDT
NSE: Loaded 3 scripts for scanning.
Initiating ARP Ping Scan at 19:29
Scanning 101 hosts [1 port/host]
...
Nmap done: 256 IP addresses (16 hosts up) scanned in 499.41 seconds
Raw packets sent: 19973 (877.822KB) | Rcvd: 15125 (609.512KB)

In addition to running Nmap, there are a variety of other port scanners that are available to us within the framework.

msf > search portscan

Matching Modules
================

   Name                                      Disclosure Date  Rank    Description
   ----                                      ---------------  ----    -----------
   auxiliary/scanner/natpmp/natpmp_portscan                   normal  NAT-PMP External Port Scanner
   auxiliary/scanner/portscan/ack                             normal  TCP ACK Firewall Scanner
   auxiliary/scanner/portscan/ftpbounce                       normal  FTP Bounce Port Scanner
   auxiliary/scanner/portscan/syn                             normal  TCP SYN Port Scanner
   auxiliary/scanner/portscan/tcp                             normal  TCP Port Scanner
   auxiliary/scanner/portscan/xmas                            normal  TCP "XMas" Port Scanner

For the sake of comparison, we’ll compare our Nmap scan results for port 80 with a Metasploit scanning module. First, let’s determine what hosts had port 80 open according to Nmap.

msf > cat subnet_1.gnmap | grep 80/open | awk '{print $2}'
[*] exec: cat subnet_1.gnmap | grep 80/open | awk '{print $2}'

192.168.1.1
192.168.1.2
192.168.1.10
192.168.1.109
192.168.1.116
192.168.1.150

The Nmap scan we ran earlier was a SYN scan so we’ll run the same scan across the subnet looking for port 80 through our eth0 interface, using Metasploit.

msf > use auxiliary/scanner/portscan/syn
msf auxiliary(syn) > show options

Module options (auxiliary/scanner/portscan/syn):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   BATCHSIZE  256              yes       The number of hosts to scan per set
   DELAY      0                yes       The delay between connections, per thread, in milliseconds
   INTERFACE                   no        The name of the interface
   JITTER     0                yes       The delay jitter factor (maximum value by which to +/- DELAY) in milliseconds.
   PORTS      1-10000          yes       Ports to scan (e.g. 22-25,80,110-900)
   RHOSTS                      yes       The target address range or CIDR identifier
   SNAPLEN    65535            yes       The number of bytes to capture
   THREADS    1                yes       The number of concurrent threads
   TIMEOUT    500              yes       The reply read timeout in milliseconds

msf auxiliary(syn) > set INTERFACE eth0
INTERFACE => eth0
msf auxiliary(syn) > set PORTS 80
PORTS => 80
msf auxiliary(syn) > set RHOSTS 192.168.1.0/24
RHOSTS => 192.168.1.0/24
msf auxiliary(syn) > set THREADS 50
THREADS => 50
msf auxiliary(syn) > run

[*] TCP OPEN 192.168.1.1:80
[*] TCP OPEN 192.168.1.2:80
[*] TCP OPEN 192.168.1.10:80
[*] TCP OPEN 192.168.1.109:80
[*] TCP OPEN 192.168.1.116:80
[*] TCP OPEN 192.168.1.150:80
[*] Scanned 256 of 256 hosts (100% complete)
[*] Auxiliary module execution completed

Here we’ll load up the ‘tcp’ scanner and we’ll use it against another target. As with all the previously mentioned plugins, this uses the ‘RHOSTS’ option. Remember we can issue the hosts -R command to automatically set this option with the hosts found in our database.

msf > use auxiliary/scanner/portscan/tcp
msf  auxiliary(tcp) > show options

Module options (auxiliary/scanner/portscan/tcp):

   Name         Current Setting  Required  Description
   ----         ---------------  --------  -----------
   CONCURRENCY  10               yes       The number of concurrent ports to check per host
   DELAY        0                yes       The delay between connections, per thread, in milliseconds
   JITTER       0                yes       The delay jitter factor (maximum value by which to +/- DELAY) in milliseconds.
   PORTS        1-10000          yes       Ports to scan (e.g. 22-25,80,110-900)
   RHOSTS                        yes       The target address range or CIDR identifier
   THREADS      1                yes       The number of concurrent threads
   TIMEOUT      1000             yes       The socket connect timeout in milliseconds

msf  auxiliary(tcp) > hosts -R

Hosts
=====

address         mac                name  os_name  os_flavor  os_sp  purpose  info  comments
-------         ---                ----  -------  ---------  -----  -------  ----  --------
172.16.194.172  00:0C:29:D1:62:80        Linux    Ubuntu            server

RHOSTS => 172.16.194.172

msf  auxiliary(tcp) > show options

Module options (auxiliary/scanner/portscan/tcp):

   Name         Current Setting  Required  Description
   ----         ---------------  --------  -----------
   CONCURRENCY  10               yes       The number of concurrent ports to check per host
   FILTER                        no        The filter string for capturing traffic
   INTERFACE                     no        The name of the interface
   PCAPFILE                      no        The name of the PCAP capture file to process
   PORTS        1-1024           yes       Ports to scan (e.g. 22-25,80,110-900)
   RHOSTS       172.16.194.172   yes       The target address range or CIDR identifier
   SNAPLEN      65535            yes       The number of bytes to capture
   THREADS      10                yes       The number of concurrent threads
   TIMEOUT      1000             yes       The socket connect timeout in milliseconds

msf  auxiliary(tcp) > run

[*] 172.16.194.172:25 - TCP OPEN
[*] 172.16.194.172:23 - TCP OPEN
[*] 172.16.194.172:22 - TCP OPEN
[*] 172.16.194.172:21 - TCP OPEN
[*] 172.16.194.172:53 - TCP OPEN
[*] 172.16.194.172:80 - TCP OPEN
[*] 172.16.194.172:111 - TCP OPEN
[*] 172.16.194.172:139 - TCP OPEN
[*] 172.16.194.172:445 - TCP OPEN
[*] 172.16.194.172:514 - TCP OPEN
[*] 172.16.194.172:513 - TCP OPEN
[*] 172.16.194.172:512 - TCP OPEN
[*] Scanned 1 of 1 hosts (100% complete)
[*] Auxiliary module execution completed
msf  auxiliary(tcp) >

We can see that Metasploit’s built-in scanner modules are more than capable of finding systems and open ports for us. It’s just another excellent tool to have in your arsenal if you happen to be running Metasploit on a system without Nmap installed.

Now that we have determined which hosts are available on the network, we can attempt to determine the operating systems they are running. This will help us narrow down our attacks to target a specific system and will stop us from wasting time on those that aren’t vulnerable to a particular exploit.

Since there are many systems in our scan that have port 445 open, we will use the scanner/smb/version module to determine which version of Windows is running on a target and which Samba version is on a Linux host.

msf > use auxiliary/scanner/smb/smb_version
msf auxiliary(smb_version) > set RHOSTS 192.168.1.200-210
RHOSTS => 192.168.1.200-210
msf auxiliary(smb_version) > set THREADS 11
THREADS => 11
msf auxiliary(smb_version) > run

[*] 192.168.1.209:445 is running Windows 2003 R2 Service Pack 2 (language: Unknown) (name:XEN-2K3-FUZZ) (domain:WORKGROUP)
[*] 192.168.1.201:445 is running Windows XP Service Pack 3 (language: English) (name:V-XP-EXPLOIT) (domain:WORKGROUP)
[*] 192.168.1.202:445 is running Windows XP Service Pack 3 (language: English) (name:V-XP-DEBUG) (domain:WORKGROUP)
[*] Scanned 04 of 11 hosts (036% complete)
[*] Scanned 09 of 11 hosts (081% complete)
[*] Scanned 11 of 11 hosts (100% complete)
[*] Auxiliary module execution completed

Also notice that if we issue the hosts command now, the newly-acquired information is stored in Metasploit’s database.

msf auxiliary(smb_version) > hosts

Hosts
=====

address        mac  name  os_name            os_flavor  os_sp  purpose  info  comments
-------        ---  ----  -------            ---------  -----  -------  ----  --------
192.168.1.201             Microsoft Windows  XP         SP3    client
192.168.1.202             Microsoft Windows  XP         SP3    client
192.168.1.209             Microsoft Windows  2003 R2    SP2    server

Nmap’s IPID Idle scanning allows us to be a little stealthy scanning a target while spoofing the IP address of another host on the network. In order for this type of scan to work, we will need to locate a host that is idle on the network and uses IPID sequences of either Incremental or Broken Little-Endian Incremental. Metasploit contains the module scanner/ip/ipidseq to scan and look for a host that fits the requirements.

In the free online Nmap book, you can find out more information on Nmap Idle Scanning.

msf > use auxiliary/scanner/ip/ipidseq
msf auxiliary(ipidseq) > show options

Module options (auxiliary/scanner/ip/ipidseq):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   INTERFACE                   no        The name of the interface
   RHOSTS                      yes       The target address range or CIDR identifier
   RPORT      80               yes       The target port
   SNAPLEN    65535            yes       The number of bytes to capture
   THREADS    1                yes       The number of concurrent threads
   TIMEOUT    500              yes       The reply read timeout in milliseconds

msf auxiliary(ipidseq) > set RHOSTS 192.168.1.0/24
RHOSTS => 192.168.1.0/24
msf auxiliary(ipidseq) > set THREADS 50
THREADS => 50
msf auxiliary(ipidseq) > run

[*] 192.168.1.1's IPID sequence class: All zeros
[*] 192.168.1.2's IPID sequence class: Incremental!
[*] 192.168.1.10's IPID sequence class: Incremental!
[*] 192.168.1.104's IPID sequence class: Randomized
[*] 192.168.1.109's IPID sequence class: Incremental!
[*] 192.168.1.111's IPID sequence class: Incremental!
[*] 192.168.1.114's IPID sequence class: Incremental!
[*] 192.168.1.116's IPID sequence class: All zeros
[*] 192.168.1.124's IPID sequence class: Incremental!
[*] 192.168.1.123's IPID sequence class: Incremental!
[*] 192.168.1.137's IPID sequence class: All zeros
[*] 192.168.1.150's IPID sequence class: All zeros
[*] 192.168.1.151's IPID sequence class: Incremental!
[*] Auxiliary module execution completed

Judging by the results of our scan, we have a number of potential zombies we can use to perform idle scanning. We’ll try scanning a host using the zombie at 192.168.1.109 and see if we get the same results we had earlier.

msf auxiliary(ipidseq) > nmap -Pn -sI 192.168.1.109 192.168.1.114
[*] exec: nmap -Pn -sI 192.168.1.109 192.168.1.114

Starting Nmap 5.00 ( http://nmap.org ) at 2009-08-14 05:51 MDT
Idle scan using zombie 192.168.1.109 (192.168.1.109:80); Class: Incremental
Interesting ports on 192.168.1.114:
Not shown: 996 closed|filtered ports
PORT STATE SERVICE
135/tcp open msrpc
139/tcp open netbios-ssn
445/tcp open microsoft-ds
3389/tcp open ms-term-serv
MAC Address: 00:0C:29:41:F2:E8 (VMware)

Nmap done: 1 IP address (1 host up) scanned in 5.56 seconds