Archangel Amael's Blog: network mapper

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Sunday, January 13, 2008

Multipart PortScanning Tutorial Part 5

Multipart PortScanning Tutorial Part 5

In this edition we will be looking at the results of NULL Scans.
We are using Nmap

The other parts are located here:
Part1
Part2
Part3
Part4

Disclaimer: This information is for educational purposes only and not to commit a crime!
If you do something that causes you to hose your box don't come kicking and screaming on the forums!
All IP Address' MAC Address' etc. have been munged!

Ok first off a NULL Scan is a scan in which there are no TCP Flags set. This is normally something that doesn't happen or shouldn't happen in the "real world". If the scanned ports are closed then we should get a RST (Reset) packet back from our target.

The basic scan uses the -sN flag.

So it will look like the following on a windows box with a firewall in place.

Code:

 bt ~# nmap -sN -vv 192.168.1.4

As always we are using the -vv (very verbose) flags.
And the following is our typical output:

Code:

Starting Nmap 4.20 ( http://insecure.org ) at 2008
Initiating ARP Ping Scan at 11:35
Scanning 192.168.1.4 [1 port]
Completed ARP Ping Scan at 11:35, 0.01s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 11:35
Completed Parallel DNS resolution of 1 host. at 11:35, 0.05s elapsed
Initiating NULL Scan at 11:35
Scanning 192.168.1.4 [1697 ports]
Completed NULL Scan at 11:36, 36.33s elapsed (1697 total ports)
Host 192.168.1.4 appears to be up ... good.
All 1697 scanned ports on 192.168.1.4 are open|filtered
MAC Address: 00:11:22:AA:BB:CC (Cisco-Linksys, LLC)

Nmap finished: 1 IP address (1 host up) scanned in 37.093 seconds
            Raw packets sent: 3395 (135.802KB) | Rcvd: 1 (42B)

And now the same scan without the firewall in place.

Code:

 bt ~# nmap -sN -vv 192.168.1.4

This time I will show only the info that is relevant.

Code:

Starting Nmap 4.20 ( http://insecure.org ) at 2008
All 1697 scanned ports on 192.168.1.4 are closed
MAC Address: 00:11:22:AA:BB:CC (Cisco-Linksys, LLC)

Notice the difference? The only thing is that now the ports are showing up as closed! This is a huge bit of information.
We also learned in both that the host is "up" as well as the network interface's MAC address.
But most importantly we probably didn't set off any alarms on the target network.
Because I did this on my network I know that it didn't.

Now lets look at one more scan, only this time we will do it against a *nix box.

Code:

 bt ~# nmap -sN -vv 192.168.1.101

Again the output shows only what is relevant.

Code:

Starting Nmap 4.20 ( http://insecure.org ) at 2008

Host 192.168.1.101 appears to be up ... good.
All 1697 scanned ports on 192.168.1.101 are open|filtered
MAC Address: 11:00:22:AA:BB:CC (Cisco-Linksys, LLC)

Nmap finished: 1 IP address (1 host up) scanned in 36.094 seconds
            Raw packets sent: 3395 (135.802KB) | Rcvd: 1 (42B)

This time we see that the *nix box showed the ports as being in a open or filtered state.

The advantage of doing a NULL Scan are no TCP sessions are created for this scan, it is normally quiet from the perspective of the remote device's applications. Therefore, none of these scans should appear in any of the application logs. This is a huge advantage when scanning a firewall or router that is facing the internet on a target network. These scans are also some of the most minimal port-level scans that nmap can do. For a closed port, only two packets are transferred. This is all that is needed to find an open port!

The Disadvantages of doing this type of scan are, Some implementations of the TCP stack will render this scan useless. For instance with Microsoft this scan will show all ports as closed regardless of their actual state. But even this can work to your advantage, since any device showing open ports must not be a Windows-based device!
There is another caveat to the above, Software based firewalls can override this rule, as shown in the first scan.

So now that we know what a NULL Scan can do for us or against us we should be able to better protect our networks.
Ideally and in my opinion we want our box to respond as being open | filtered as shown above. This makes it harder for an intruder to guess what the target is.

Sunday, January 6, 2008

Multipart PortScanning Tutorial Part 4

In part four of our "scanning journey" we are looking at FIN scans against our target box.
I am going to show you various combinations of the FIN scan and the resulting output.
If you have not done so you may need to brush up on the other lessons.

Part1
Part2
Part3

Disclaimer: This information is for educational purposes only and not to commit a crime!
If you do something that causes you to hose your box don't come kicking and screaming on the forums!
All IP Address' MAC Address' etc. have been munged!

This is our standard FIN Scan. Again this is a TCP SCAN NOT UDP. I am using the Insane scan because it is a local network with the firewall and IDS turned off! So no need to worry about that.
Remember if you are doing this on a network that is not yours outside of the legality issues remember the faster you go the more likely you will be discovered by IDS/IPS (Intrusion Detection Systems/ Intrusion Prevention Systems). If a firewall was turned on then we probably won't get much in the way of information. However we will see that a little later on in this lesson.

OK on a FIN scan we are only sending FIN or "Finished packets" to our target. This tells the target who we prior to our scan did not actually "talk" to so in essence we are "finishing a conversation" or connection that never took place. This will normally net us some weird results. Sometimes the target can get confused and tell us more than it should! Sometimes it will not say anything and that it what a good hardened target box should do!

These probes are only using the default port list not the entire range of ports. All Scans listed are with the "-vv" very verbose and
"-T5" Insane speed level.

Code:

bt~# nmap -sV -T5 -vv 192.168.102

Code:

Starting Nmap 4.20 ( http://insecure.org ) at 2008
All 1697 scanned ports on 192.168.1.102 are open|filtered
MAC Address: 00:11:22:AA:BB:CC (Cisco-Linksys, LLC)

Nmap finished: 1 IP address (1 host up) scanned in 36.649 seconds

We didn't get much in the way of info with just the basic scan so we are moving on. This time using the version probe and the OS detection
Our command looks like this:

Code:

nmap -sF -sV -O -T5 -vv 192.168.1.102

And our output is as follows.

Code:

Starting Nmap 4.20 ( http://insecure.org ) at 2008
Initiating ARP Ping Scan at 11:43
Scanning 192.168.1.102 [1 port]
Completed ARP Ping Scan at 11:43, 0.01s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 11:43
Completed Parallel DNS resolution of 1 host. at 11:43, 0.05s elapsed
Initiating FIN Scan at 11:43
Scanning 192.168.1.102 [1697 ports]
Completed FIN Scan at 11:44, 2.31s elapsed (1697 total ports)
Initiating Service scan at 11:44
Warning:  OS detection for 192.168.1.102 will be MUCH less reliable because we did not find at least 1 open and 1 closed TCP port
Initiating OS detection (try #1) against 192.168.1.102
Host 192.168.1.102 appears to be up ... good.
All 1697 scanned ports on 192.168.1.102 are closed
MAC Address:00:11:22:AA:BB:CC (Cisco-Linksys, LLC)
Device type: general purpose
Running: Microsoft Windows 2003
OS details: Microsoft Windows 2003 Server SP1, Microsoft Windows Server 2003 Enterprise Edition 64-Bit SP1 (firewall disabled)
OS Fingerprint:
OS:SCAN THIS PART WAS INTENTIONALLY REMOVED BY ME!!

Network Distance: 5  hops

OS and Service detection performed. Please report any incorrect results at http://insecure.org/nmap/submit/ .
Nmap finished: 1 IP address (1 host up) scanned in 2.880 seconds
            Raw packets sent: 1839 (74.156KB) | Rcvd: 1704 (78.744KB)

An now the same scan with a firewall in place.

Code:

Starting Nmap 4.20 ( http://insecure.org ) at 2008
Initiating ARP Ping Scan at 12:05
Scanning 192.168.1.102 [1 port]
Completed ARP Ping Scan at 12:05, 0.01s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 12:05
Completed Parallel DNS resolution of 1 host. at 12:05, 0.05s elapsed
Initiating FIN Scan at 12:05
Scanning 192.168.1.102 [1697 ports]
Completed FIN Scan at 12:05, 18.93s elapsed (1697 total ports)
Initiating Service scan at 12:05
Scanning 1689 services on 192.168.1.102
Service scan Timing: About 6.42% done; ETC: 12:13 (0:07:17 remaining)
Completed Service scan at 12:12, 425.24s elapsed (1697 services on 1 host)
Warning:  OS detection for 192.168.1.102 will be MUCH less reliable because we did not find at least 1 open and 1 closed TCP port
Initiating OS detection (try #1) against 192.168.1.102
Host 192.168.1.102 appears to be up ... good.
All 1697 scanned ports on 192.168.1.102 are open|filtered
MAC Address: 00:11:22:AA:BB:CC (Cisco-Linksys, LLC)
Too many fingerprints match this host to give specific OS details
TCP/IP fingerprint by osscan system #2:
SCAN(P=i686-pc-linux-gnu)
U1(R=N)
IE(R=N)
Network Distance: 5 hops

OS and Service detection performed. Please report any incorrect results at http://insecure.org/nmap/submit/ .
Nmap finished: 1 IP address (1 host up) scanned in 445.304 seconds
            Raw packets sent: 3419 (139.138KB) | Rcvd: 1 (42B)

Notice this time in the first scan we went from a possible Windows 2003 Server type box to a possible Linux box. The only difference was the addition of a firewall that was thrown in the mix. This can make a HUGE difference when we are looking for attack vectors!

This lesson shows you what FIN Scans look like. Remember that you can change some of the other options in Nmap to help evade and spoof IDS/IPS etc.
However right now we are only concerned with the basics.
In the next lesson we will be looking at a FIN|ACK scan.

Saturday, January 5, 2008

Multipart PortScanning Tutorial Part 3

We will now continue with our "scanning journey". In this installment we are going to look at another TCP scan using
BT2 as our target machine. I am also using the latest version of Nmap on a windows box.

Disclaimer: This information is for educational purposes only and not to commit a crime!
If you do something that causes you to hose your box don't come kicking and screaming on the forums!

On our third installment we are going to look at out BT2 box. This is a fresh install of BT2 on a HDD. This will show exactly what it is others may see if you are running BT2 on your network. Now keep in mind things may be different for each individual setup possibility.

I used the latest version of Nmap it comes complete with a nice GUI if you are so inclined. I was since its on a windows box anyway! And yes you can get this for yourBT2 or 3 Box.
The only reason I did it that way is because I only have one BT Box setup right now and it was the easiest option for me. However If you have the option then go for it and post your results here as well!

So we used the same basic commands as before and it looks like:

Code:

 # nmap -A -v 192.168.1.102

Again this is still a TCP SYN Scan.
The output shows us the following:

Code:

 Starting Nmap 4.52 ( http://insecure.org ) at 2008-01-05 22:42
Initiating ARP Ping Scan at 22:42
Scanning 192.168.1.100 [1 port]
Completed ARP Ping Scan at 22:42, 0.22s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 22:42
Completed Parallel DNS resolution of 1 host. at 22:42, 0.05s elapsed
Initiating SYN Stealth Scan at 22:42
Scanning 192.168.1.100 [1714 ports]
Discovered open port 6000/tcp on 192.168.1.102
Discovered open port 631/tcp on 192.168.1.102
Completed SYN Stealth Scan at 22:42, 0.19s elapsed (1714 total ports)
Initiating Service scan at 22:42
Scanning 2 services on 192.168.1.102
Completed Service scan at 22:43, 6.02s elapsed (2 services on 1 host)
Initiating OS detection (try #1) against 192.168.1.102
SCRIPT ENGINE: Initiating script scanning.
Host 192.168.1.102 appears to be up ... good.
Interesting ports on 192.168.1.102:
Not shown: 1712 closed ports
PORT     STATE SERVICE VERSION
631/tcp  open  ipp     CUPS 1.1
6000/tcp open  X11      (access denied)
MAC Address:  00:11:22:AA:BB:CC (Cisco-Linksys, LLC)
Device type: general purpose
Running: Linux 2.6.X
OS details: Linux 2.6.17 - 2.6.23, Linux 2.6.20-15-server (Ubuntu 7.04 server, x86)
Uptime: 0.050 days (since Sat Jan 05 21:30:36 2008)
Network Distance: 12 hops
TCP Sequence Prediction: Difficulty=188 (Good luck!)
IP ID Sequence Generation: All zeros
Service Info: OS: Unix

Read data files from: G:\Nmap
OS and Service detection performed. Please report any incorrect results at http://insecure.org/nmap/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 8.822 seconds
       Raw packets sent: 1737 (78.040KB) | Rcvd: 1729 (79.864KB)

Now notice the output looks a little different, however all of the information is there. Since we used the "-A"
we get our services information in the output. This is some of the critical info that malicious users need in order to compromise a system.

Notice that we have TCP port 631 ipp open, with CUPS1.1 running.
Now for those that don't know this is the service for printing under *nixes.
This would allow users to print from the machine or remote users connect and print as well. Printing (with explicit permission) over a networked computer can be fun and malicious! A malicious user could connect to a networked printer and print out anything they wanted to.

We also see that we have TCP port 6000 open with X11 running but notice is say (access denied). This is the X Window System that allows out BT box to have a desktop.
This is a service because on *nix boxes we can have multiple users from multiple locations logged onto the box itself. And those other users can have a desktop and it can be customized to their liking. Also notice that our scan tells us what kernel we are running in this case 2.6.X

The OS details is for the Distro that we are running and this can and will be different. This data is not correct however because the "signatures that Nmap is using is not correct. At the end of the report we have an option to submit incorrect results to Nmap.

We also see the Uptime of 0.050 days, with a date. This can be very useful information for us. If we scan a box over several days or weeks we may learn that A. our computer is not very stable. B. It gets turned off at night or C. The computer is malfunctioning and needs to reboot.

This can be very useful when doing our pen testing.
A computer that is constantly rebooting may be having problems that we can take advantage of!

This scan gives you a chance to see what your BT box looks like on the net. This is how others may "see" you.

Stay tuned for more scanning in our next part we will look at a FIN Scan.

If this tutorial is helping you or hindering you let me know!

The other parts are located here if you need them:

Multipart PortScanning Part 2

And yes you can get this for yourBT2 or 3 Box.
The only reason I did it that way is because I only have one BT Box setup right now and it was the easiest option for me. However If you have the option then go for it and post your results here as well!

So we used the same basic commands as before and it looks like:

Code:

 # nmap -A -v 192.168.1.102

Again this is still a TCP SYN Scan.
The output shows us the following:

Code:

 Starting Nmap 4.52 ( http://insecure.org ) at 2008-01-05 22:42
Initiating ARP Ping Scan at 22:42
Scanning 192.168.1.100 [1 port]
Completed ARP Ping Scan at 22:42, 0.22s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 22:42
Completed Parallel DNS resolution of 1 host. at 22:42, 0.05s elapsed
Initiating SYN Stealth Scan at 22:42
Scanning 192.168.1.100 [1714 ports]
Discovered open port 6000/tcp on 192.168.1.102
Discovered open port 631/tcp on 192.168.1.102
Completed SYN Stealth Scan at 22:42, 0.19s elapsed (1714 total ports)
Initiating Service scan at 22:42
Scanning 2 services on 192.168.1.102
Completed Service scan at 22:43, 6.02s elapsed (2 services on 1 host)
Initiating OS detection (try #1) against 192.168.1.102
SCRIPT ENGINE: Initiating script scanning.
Host 192.168.1.102 appears to be up ... good.
Interesting ports on 192.168.1.102:
Not shown: 1712 closed ports
PORT     STATE SERVICE VERSION
631/tcp  open  ipp     CUPS 1.1
6000/tcp open  X11      (access denied)
MAC Address:  00:11:22:AA:BB:CC (Cisco-Linksys, LLC)
Device type: general purpose
Running: Linux 2.6.X
OS details: Linux 2.6.17 - 2.6.23, Linux 2.6.20-15-server (Ubuntu 7.04 server, x86)
Uptime: 0.050 days (since Sat Jan 05 21:30:36 2008)
Network Distance: 12 hops
TCP Sequence Prediction: Difficulty=188 (Good luck!)
IP ID Sequence Generation: All zeros
Service Info: OS: Unix

Read data files from: G:\Nmap
OS and Service detection performed. Please report any incorrect results at http://insecure.org/nmap/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 8.822 seconds
        Raw packets sent: 1737 (78.040KB) | Rcvd: 1729 (79.864KB)

We also see that we have TCP port 6000 open with X11 running but notice is say (access denied). This is the X Window System that allows out BT box to have a desktop.
This is a service because on *nix boxes we can have multiple users from multiple locations logged onto the box itself. And those other users can have a desktop and it can be customized to their liking. Also notice that our scan tells us what kernel we are running in this case 2.6.X

The OS details is for the Distro that we are running and this can and will be different. This data is not correct however because the "signatures that Nmap is using is not correct. At the end of the report we have an option to submit incorrect results to Nmap.

We also see the Uptime of 0.050 days, with a date. This can be very useful information for us. If we scan a box over several days or weeks we may learn that A. our computer is not very stable. B. It gets turned off at night or C. The computer is malfunctioning and needs to reboot.

This can be very useful when doing our pen testing.
A computer that is constantly rebooting may be having problems that we can take advantage of!

This scan gives you a chance to see what your BT box looks like on the net. This is how others may "see" you.

Friday, January 4, 2008

Multipart PortScanning Tutorial part 1

This is not so much a "How To" but rather a "What Is" The tutorials come latter.

Today we will be talking about Port Scanning and what it is.

Disclaimer: This information is for educational purposes only and not to commit a crime!
If you do something that causes you to hose your box don't come kicking and screaming on the forums!

Port Scanning is like a car thief walking around a busy parking lot and trying to find cars that are unlocked.
However on our computer or network. This can sometimes be bad if we leave the "doors" (ports) "unlocked" (open). When we leave ports open on the Internet it is not "if" someone will find it but "when". Port scanning software like [url=http://insecure.org/nmap/]Nmap[/url] Allows anyone to scan computers connected to a network. This can be done simply by the program sending out a request to connect to a target computer. Then it waits to see which port(s) responds or seems to be open so that it can be studied latter more in depth. Sometimes a computer doesn't respond and this information can be useful too. We will cover that more in depth latter.

When a scanner is looking for ports on a target computer it has two choices for port type. First is TCP which is the Transmission Control Protocol.This is simply the "rule set" by which data is exchanged over a network. This data exchange is bytes of data that are called packets. These packets normally consist of a "Header" and a "body". The header is the "address" of where the packet is going to. This is used by routers on a network to send the data along its way. The "body" is the information that has been sent. Think of it as a letter to grandma first you have the envelope which is the packet. You have the address to grandma which is the header, And finally you have the letter itself, which is the body of the packet. It doesn't really matter which order these packets arrive at its destination because the computer on the receiving end can put them back together in the right order.

Now UDP on the other hand does not guarantee reliability or ordering in the way that TCP does. This means that the packets can arrive out of order, they can be duplicated or become missing without notice. This sometimes makes UDP faster than TCP. We will talk more about UDP later on.

Back to port scanning. When we scan ports we have up to 65,535 to choose from. This is the same for TCP and UDP. Thats a lot of doors for us to lock and make sure they stay locked.

The first 1024 TCP ports are called the Well-Known Ports and are associated with standard services such as FTP, HTTP, SMTP or DNS.
The Registered Ports are those in the range 1024–49151.
The Dynamic and/or Private Ports are those in the range 49152–65535. Randomly chosen port numbers out of this range are called ephemeral ports. These ports are not permanently assigned to any publicly defined application.

If a port scan is being done with malicious intent, an attacker normally wants to go undetected. Network security applications can be configured to alert administrators if they detect connection requests across a broad range of ports from a single host. To get around this an attacker can do the port scan in strobe or stealth mode. Strobing limits the ports to a smaller target set rather than blanket scanning all 65535 ports. Stealth scanning uses techniques such as slowing the scan down. By scanning the ports over a much longer period of time we can better evade IDS. Although this is not always the case!

By setting different TCP flags or sending different types of packets a port scan can generate different results or locate open ports in different ways. A SYN scan will tell the port scanner which ports are listening and which are not depending on the type of response generated. This is normally accomplished by a Three-Way Handshake.
First we have the Syn Packet sent from a computer wishing to connect to another saying "let's connect". Then the computer we wish to connect to says with a SYN-ACK "ok let's connect".Then we would send another ACK back saying "ok". At this point the two computers would be "connected". If the port however was closed then we normally wouldn't get any response back.

In the next few segments we will be looking at the output of some various scans on our target machine. We will be using nmap to do this.
So until then go and read up on nmap so that you have a basic understanding of the tool.