I'm going to provide the common methodology that is followed when hacking a machine/network/server. This tutorial will give you a good understanding & an overview about professional penetration testing in a black box (attacker) point of view. It is designed to give you an idea on how an attacker can break into your system, what I am gonna say will increase your awareness & will open the door for you to go out & educate yourself easily. I gathered this information from various sources and tutorials, i have changed many things, clarified many parts, given some references, and put a lot of information together. I'm still a learner & on the way to my goal. However, this won't prevent me from teaching others what i have learned so far & don't worry, i'm not going to provide you with any info that i'm not sure about yet. It is not the best tutorial out there, but at least it is a good starter. I will speak from a hackers (attacker or blackbox) point of view.
Before you hack a system, you must decide what your goal is. Are you hacking to put the system down, gaining sensitive data, breaking into the system and taking the 'root' access, screwing up the system by formatting everything in it, discovering vulnerabilities & see how you can exploit them, etc ? The point is that you have to decide what the goal is first.
The most common goals are:
1. breaking into the system & taking the admin privileges.
2. gaining sensitive data, such as credit cards, identification theft, etc.
You should have all of your tools ready before you start taking the steps of hacking. There is a Unix version called backtrack. It is an Operating System that comes with various sets of security tools that will help you hack systems .
You should set the steps (methodology) that you plan to take in your journey before you do anything else. There is a common methodology followed
by hackers, i will mention it below. However, you can create your own methodology if you know what you are doing.
Common steps to be taken for hacking a system:
1. Reconnaissance (footprinting).
2. Scanning.
3. Ports & Services Enumeration.
4. Vulnerability Assessment.
5. Vulnerability Exploitation.
6. Penetration and Access.
7. Privilege Escalation & owning the box.
8. Erase tracks.
9. Maintaining access.
The above methodology can change based on your goals. Feel free m8!
Before you break into a system, you have to collect as much info as you can on the system and target. You have to study your target well before you hack. This step is called Reconnaissance. Reconnaissance is achieved by using techniques & tools that are undetectable by the target. You are gathering your target's info that is publicly published, e.g. browse your target's website & if they are looking for an SQL employee and Windows server admin, then you get a hint that they are running Windows Server & do SQL's, this is called a "passive" action. Lets see an example of active action! Example of active action: call the company to obtain some info, visit the company, email employees to get some info, go to the target's website & read its source code. In other words, passive action means you gather info in a non-intrusive manner. Active action is a step further, such as talking to the company as if you are a customer, things like that. It is not really important to know what action is passive & what is active, the main goal here to gather info! Simple huh? Good, let me go deeper little bit.
In passive reconnaissance, there is a 0% chance of getting caught
, as you only target publicly available info to give you the feel on what your target looks like. The type of info you can gather through Passive Recon. are, names, phones numbers, location addresses, partner networks, and much more. This can aid you when you want to do some social engineering! Hence, sometimes you can get some non-public info that's revealed when you do passive reconnaissance. There are several tools helps you to do passive reconnaissance, such as whois (who is). Whois helps you obtain extensive info, such as names, domains of the target, etc. Other great tools are, Sam Spade, domaintools, and google(can reveal lots of target subdomians & many more).
Active reconnaissance goes beyond the passive nature, such as communicating with the target without being caught, such as scanning. Anything not discovered in IDS(Intrusion Detection System) is considered active. You have to think of ways to extract info of the company in a normal way, public by going a little bit deeper than passive recon. e.g. you can go to the physical location, do some social engineering, email staff, communicate with employees based on the info you've gotten on your passive recons. Things like that!
Example of some techniques for active reconnaissance, such as banner grabbing, view company's public website source code and directory structure, social engineering, shoulder surfing, etc.
What the heck is banner grabbing?
You let the server send you a block of information that tells you OS version of your target system & various association with it
Banner tells OS version and various association. Anything listening on a "port" can determine the operating system (OS) "the port" is running on, this called fingerprinting. In other words, fingerprinting is the process of determining the operating system (OS) or applications used by a remote target.
Learn more about banner grabbing:
http://www.net-square.com/httprint/httprint_paper.html
Can you give a brief example of Social Engineering?
For example, you try to find out where IT admin goes after business hours, then start to go to the place he goes & build a relationship , start making a friend relationship to extract more info slowly but surely, things like that! you know what i mean.
What is shoulder surfing?
Simply, stand behind a person's shoulder and see what the guy is doing & typing on the keyboard. This can happen in a wireless network area where everyone is using a laptop in public areas.
In summary, reconnaissance is one of the most important steps in hacking. The main concept is to gather all the info that is publicly available or easily obtainable. Info that we gather will help us in social engineering and research purposes which will lead you to very critical info about the system. It starts by obtaining names, phones, emails, IP range, domain structure, and so on.
let me show you how banner grabbing is done, telnet into your target server on port 80 as the following, go to command line or terminal and type
telnet xx.xxx.xxx.xxx 80
Now the connection is established, that stupid server thinks you are a web browser connected to it, it waits you to enter commands so the server can you give you info about your request. In this situation, you have to write a command that says "Hey you web server, give me content of such and such website". However, we do not really want to visit the website through telnet, do you? You can just go to web browser & request the website from there. Our purpose here is to freak the server out enough, so it spits back a code that says, hey! this doesn't work but here is some info that might help you do some trouble shooting. This technique allows you to fingerprint various components of the target system.
Note: instead of telnet xxx.xx.xxx.xx 80, you can do nc xxx.xx.xxx.xxx 80! It's the same thing ... nc stands for netcat ... xx.xxx.xx.xxx represents the IP address of the target system.
After you do telnet xxx.xx.xxx.xxx 80, the remote sever will wait you to enter a command. Type this:
HEAD / HTTP/1.0
Then you will get a reply looks similar to:-
HTTP/1.1 200 OK
Date: Mon, 16 Jun 2003 02:53:29 GMT
Server: Apache/1.3.3 (Unix) (Red Hat/Linux)
Last-Modified: Wed, 07 Oct 1998 11:18:14 GMT
ETag: "1813-49b-361b4df6"
Accept-Ranges: bytes
Content-Length: 1179
Connection: close
Content-Type: text/html
So the header response brought back some important info that says, the server runs: Apache/1.3.23 in UNIX OS for Red Hat distribution of Linux.
OR you might get header that looks similar to the following:
HTTP/1.1 200 OK
Server: Microsoft-IIS/5.0
Expires: Tue, 17 Jun 2003 01:41:33 GMT
Date: Mon, 16 Jun 2003 01:41:33 GMT
Content-Type: text/html
Accept-Ranges: bytes
Last-Modified: Wed, 28 May 2003 15:32:21 GMT
ETag: "b0aac0542e25c31:89d"
Content-Length: 7369
It means, the server runs: Microsoft-IIS/5.0 in Win 2000 or Win 2003 (we don't the Windows version yet).
OR you might get header that looks similar to the following:
Date: Thu, 04 Dec 2008 02:18:46 GMT
Server: Apache/1.3.41 (Unix) PHP/4.4.8 mod_gzip/1.3.26.1a mod_log_bytes/1.2 mod_bwlimited/1.4 mod_ssl/2.8.31 OpenSSL/0.9.8b
Last-Modified: Thu, 10 Jul 2008 23:34:28 GMT
ETag: "c9865b-d91-48769c84"
Accept-Ranges: bytes
Content-Length: 3473
Connection: close
Content-Type: text/html
It means, the server runs: Apache/1.3.41 in UNIX box, running PHP/4.4.8
Ok, you get it now?
lets say our target got the following version: the server runs: Apache/1.3.41 in UNIX box, running PHP/4.4.8
At this point if you know any vulnerabilities for this particular OS or this particular Apache or PHP. You can start the exploitation process ...
Another example, use program called sam-spade which gives you alot of info about your target. The target does not know actually what we are doing against their server, since they haven't seen anything been triggered by IDS or Firewall.
*What is the difference between IDS & Firewall?
An IDS (Intrusion Detection System) may only detect and warn you of a violation of your privacy. Although most block major attacks, some probes or other attacks may just be noted and allowed through. There's also an evolution of the IDS called an IPS (Intrusion Prevention System) that watches for the same things an IDS does, but instead of just alerting, it blocks the traffic.
A good firewall will block almost all attacks unless specified otherwise or designed otherwise. The only problem is, the firewall might not warn you of the attacks and may just block them.
It may be a good idea to have both an IDS and a Firewall, because the IDS will warn you and then the firewall will block the attack. Over the years, firewalls gottten more complex and added more features. One of these features is actually IDS - today you can have a firewall that already has IDS(Firewall/IDS's are combined into one internet security program).
Learn more about banner grabbing:
http://www.net-square.com/httprint/httprint_paper.html
To learn how to do it through Google, you need the following book:
http://www.amazon.com/exec/obidos/ASIN/1.../ref=nosim
Note: the book in amazon is just an example for you to give you an idea of what kind of book you should be looking for - if you are interested.
Alright, now you at least have an idea of what reconnaissance is! lets talk about scanning...
When you scan your target's network, you actually start touching the system. Scanning a network determines what's in there, scanning network gives you the feel of how your target's network is laid out, if there are multiple subnets, which hosts are alive, check ports, see if system is alive, discover available hosts & get info about the discovered hosts. There are thousands of tools can be used to scan networks! Scanning a network can easily get picked up by IDS. Anyhow, no one will pay attention except if you do it over and over because scans happens on such a regular basis on the internet. Therefore, people who read the logs, i means the webmaster won't really pay attention to every single scan that occurs, so you don't have to worry alot. There are ways to avoid being picked up by IDS
. After you finish scanning, you will gain a list of network nodes that exists there.
"Node" is an active electronic device that is attached to a network, and is capable of sending, receiving, or forwarding information over a communications channel. If you want to learn more, google it or visit http://en.wikipedia.org/wiki/Node_(networking) ...
Ok now we want to discover live hosts via scanning. This is the first action taken against your target's network. Depending on what method of scanning you use, you can be detected by IDS. Most admins will ignore detections because it happens alot unless something abnormal happens.
EDIT: TEMPORARY STOPPING POINT OF GRAMMATICAL EDITING
There are various scanner tools, e.g. nmap, superscan, and many more. There are various scan methods, some are stealthy, others are not.
Before i talk about various scanning methods, let me explain to you about TCP connections basics. When you scan your target using TCP communication, there are six TCP flags can be utilized during packet transmission(packets get transmitted during scanning process). A flag will indicate whether the sent packets are syn, ack, fin, urg, psh, or rst packets. These packets sets you in a position on how you want to communicate with the remote host. You can get different info depending on the flag you choose for the scanning.
TCP establishes three handshakes, syn, syn-ack, ack. What are they?
When you scan your target using TCP communication, you send a syn packet(syn request), and then target sends you back an ack packet with syn packet. Now, you send an ack packet to the target. So now both machines establish the connection well, like they have made a well established tunnel for a proper guaranteed communication without losing any packets during communicating with each other. A hacker can get caught easily if he uses this method to hack other systems illegally.
Hackers use non-standard combination of these six flags, which gives them info that are not normally available to the public.
Have you heard about syn flood?
syn flood is done by utilizing three handshake by sending "syn" request to the target, so the target receives a syn request and send an a syn-ack back to the originator(you). You ignore the target syn-ack request - when you ignore it, then the three handshakes is not completed, this is called half open TCP connection - In theory, when the target sends you syn-ack, the target allocates some RAM on its machine.
The amount of RAM on the target machine must be open until it gets response (ack packet) back from you because till now only two handshake has been made,so the TCP connection process is not completed yet. However, there is always a time limit for the RAM to be opened, so if 30 secs passed by & the target did not get the ack from you, the connection will abort(failed TCP handshake - timeout) & RAM will be deallocated.
The idea here is to send hell alot of packets in few secs so in 30 secs, you can send 40 million packets(lets say one packet size is 1kb) which is heavy on the RAM since the RAM might not have enough memory to carry 40 million packets. Therefore, you force the target to make half open TCP connection attempts, so definitely the target machine will stop responding to legitimate request. In other words, if you send 40 million syn requests to that remote host, it's going to allocate a hell of a lot of ram for those requests. After a while, it's going to eat up all of the ram. Thus, target system goes down. This is called syn flood attack.
In short, syn flood attack makes the system (i.e. the IP stack or kernel) chokes on the memory allocations (or simply runs out of memory) or the target application (i.e. web server) chokes on the processing load. You got it? Or not yet?! Syn flood is an old technique i just mentioned it here for illustration purposes.
General Info-: these days, SYN floods are used to make systems inaccessible. They have a limited number of half open connections, you use them all, and they can't accept any more SYNs. But again, modern software throws away old SYNs once the limit is reached. Note that different systems will behave differently.
If you interested in learning more about syn flood, visit
http://tools.ietf.org/html/rfc4987
part 2
Before you hack a system, you must decide what your goal is. Are you hacking to put the system down, gaining sensitive data, breaking into the system and taking the 'root' access, screwing up the system by formatting everything in it, discovering vulnerabilities & see how you can exploit them, etc ? The point is that you have to decide what the goal is first.
The most common goals are:
1. breaking into the system & taking the admin privileges.
2. gaining sensitive data, such as credit cards, identification theft, etc.
You should have all of your tools ready before you start taking the steps of hacking. There is a Unix version called backtrack. It is an Operating System that comes with various sets of security tools that will help you hack systems .
You should set the steps (methodology) that you plan to take in your journey before you do anything else. There is a common methodology followed
by hackers, i will mention it below. However, you can create your own methodology if you know what you are doing.
Common steps to be taken for hacking a system:
1. Reconnaissance (footprinting).
2. Scanning.
3. Ports & Services Enumeration.
4. Vulnerability Assessment.
5. Vulnerability Exploitation.
6. Penetration and Access.
7. Privilege Escalation & owning the box.
8. Erase tracks.
9. Maintaining access.
The above methodology can change based on your goals. Feel free m8!
Before you break into a system, you have to collect as much info as you can on the system and target. You have to study your target well before you hack. This step is called Reconnaissance. Reconnaissance is achieved by using techniques & tools that are undetectable by the target. You are gathering your target's info that is publicly published, e.g. browse your target's website & if they are looking for an SQL employee and Windows server admin, then you get a hint that they are running Windows Server & do SQL's, this is called a "passive" action. Lets see an example of active action! Example of active action: call the company to obtain some info, visit the company, email employees to get some info, go to the target's website & read its source code. In other words, passive action means you gather info in a non-intrusive manner. Active action is a step further, such as talking to the company as if you are a customer, things like that. It is not really important to know what action is passive & what is active, the main goal here to gather info! Simple huh? Good, let me go deeper little bit.
In passive reconnaissance, there is a 0% chance of getting caught
, as you only target publicly available info to give you the feel on what your target looks like. The type of info you can gather through Passive Recon. are, names, phones numbers, location addresses, partner networks, and much more. This can aid you when you want to do some social engineering! Hence, sometimes you can get some non-public info that's revealed when you do passive reconnaissance. There are several tools helps you to do passive reconnaissance, such as whois (who is). Whois helps you obtain extensive info, such as names, domains of the target, etc. Other great tools are, Sam Spade, domaintools, and google(can reveal lots of target subdomians & many more).Active reconnaissance goes beyond the passive nature, such as communicating with the target without being caught, such as scanning. Anything not discovered in IDS(Intrusion Detection System) is considered active. You have to think of ways to extract info of the company in a normal way, public by going a little bit deeper than passive recon. e.g. you can go to the physical location, do some social engineering, email staff, communicate with employees based on the info you've gotten on your passive recons. Things like that!
Example of some techniques for active reconnaissance, such as banner grabbing, view company's public website source code and directory structure, social engineering, shoulder surfing, etc.
What the heck is banner grabbing?
You let the server send you a block of information that tells you OS version of your target system & various association with it
Banner tells OS version and various association. Anything listening on a "port" can determine the operating system (OS) "the port" is running on, this called fingerprinting. In other words, fingerprinting is the process of determining the operating system (OS) or applications used by a remote target.
Learn more about banner grabbing:
http://www.net-square.com/httprint/httprint_paper.html
Can you give a brief example of Social Engineering?
For example, you try to find out where IT admin goes after business hours, then start to go to the place he goes & build a relationship , start making a friend relationship to extract more info slowly but surely, things like that! you know what i mean.
What is shoulder surfing?
Simply, stand behind a person's shoulder and see what the guy is doing & typing on the keyboard. This can happen in a wireless network area where everyone is using a laptop in public areas.
In summary, reconnaissance is one of the most important steps in hacking. The main concept is to gather all the info that is publicly available or easily obtainable. Info that we gather will help us in social engineering and research purposes which will lead you to very critical info about the system. It starts by obtaining names, phones, emails, IP range, domain structure, and so on.
let me show you how banner grabbing is done, telnet into your target server on port 80 as the following, go to command line or terminal and type
telnet xx.xxx.xxx.xxx 80
Now the connection is established, that stupid server thinks you are a web browser connected to it, it waits you to enter commands so the server can you give you info about your request. In this situation, you have to write a command that says "Hey you web server, give me content of such and such website". However, we do not really want to visit the website through telnet, do you? You can just go to web browser & request the website from there. Our purpose here is to freak the server out enough, so it spits back a code that says, hey! this doesn't work but here is some info that might help you do some trouble shooting. This technique allows you to fingerprint various components of the target system.
Note: instead of telnet xxx.xx.xxx.xx 80, you can do nc xxx.xx.xxx.xxx 80! It's the same thing ... nc stands for netcat ... xx.xxx.xx.xxx represents the IP address of the target system.
After you do telnet xxx.xx.xxx.xxx 80, the remote sever will wait you to enter a command. Type this:
HEAD / HTTP/1.0
Then you will get a reply looks similar to:-
HTTP/1.1 200 OK
Date: Mon, 16 Jun 2003 02:53:29 GMT
Server: Apache/1.3.3 (Unix) (Red Hat/Linux)
Last-Modified: Wed, 07 Oct 1998 11:18:14 GMT
ETag: "1813-49b-361b4df6"
Accept-Ranges: bytes
Content-Length: 1179
Connection: close
Content-Type: text/html
So the header response brought back some important info that says, the server runs: Apache/1.3.23 in UNIX OS for Red Hat distribution of Linux.
OR you might get header that looks similar to the following:
HTTP/1.1 200 OK
Server: Microsoft-IIS/5.0
Expires: Tue, 17 Jun 2003 01:41:33 GMT
Date: Mon, 16 Jun 2003 01:41:33 GMT
Content-Type: text/html
Accept-Ranges: bytes
Last-Modified: Wed, 28 May 2003 15:32:21 GMT
ETag: "b0aac0542e25c31:89d"
Content-Length: 7369
It means, the server runs: Microsoft-IIS/5.0 in Win 2000 or Win 2003 (we don't the Windows version yet).
OR you might get header that looks similar to the following:
Date: Thu, 04 Dec 2008 02:18:46 GMT
Server: Apache/1.3.41 (Unix) PHP/4.4.8 mod_gzip/1.3.26.1a mod_log_bytes/1.2 mod_bwlimited/1.4 mod_ssl/2.8.31 OpenSSL/0.9.8b
Last-Modified: Thu, 10 Jul 2008 23:34:28 GMT
ETag: "c9865b-d91-48769c84"
Accept-Ranges: bytes
Content-Length: 3473
Connection: close
Content-Type: text/html
It means, the server runs: Apache/1.3.41 in UNIX box, running PHP/4.4.8
Ok, you get it now?
lets say our target got the following version: the server runs: Apache/1.3.41 in UNIX box, running PHP/4.4.8
At this point if you know any vulnerabilities for this particular OS or this particular Apache or PHP. You can start the exploitation process
...Another example, use program called sam-spade which gives you alot of info about your target. The target does not know actually what we are doing against their server, since they haven't seen anything been triggered by IDS or Firewall.
*What is the difference between IDS & Firewall?
An IDS (Intrusion Detection System) may only detect and warn you of a violation of your privacy. Although most block major attacks, some probes or other attacks may just be noted and allowed through. There's also an evolution of the IDS called an IPS (Intrusion Prevention System) that watches for the same things an IDS does, but instead of just alerting, it blocks the traffic.
A good firewall will block almost all attacks unless specified otherwise or designed otherwise. The only problem is, the firewall might not warn you of the attacks and may just block them.
It may be a good idea to have both an IDS and a Firewall, because the IDS will warn you and then the firewall will block the attack. Over the years, firewalls gottten more complex and added more features. One of these features is actually IDS - today you can have a firewall that already has IDS(Firewall/IDS's are combined into one internet security program).
Learn more about banner grabbing:
http://www.net-square.com/httprint/httprint_paper.html
To learn how to do it through Google, you need the following book:
http://www.amazon.com/exec/obidos/ASIN/1.../ref=nosim
Note: the book in amazon is just an example for you to give you an idea of what kind of book you should be looking for - if you are interested.
Alright, now you at least have an idea of what reconnaissance is! lets talk about scanning...
When you scan your target's network, you actually start touching the system. Scanning a network determines what's in there, scanning network gives you the feel of how your target's network is laid out, if there are multiple subnets, which hosts are alive, check ports, see if system is alive, discover available hosts & get info about the discovered hosts. There are thousands of tools can be used to scan networks! Scanning a network can easily get picked up by IDS. Anyhow, no one will pay attention except if you do it over and over because scans happens on such a regular basis on the internet. Therefore, people who read the logs, i means the webmaster won't really pay attention to every single scan that occurs, so you don't have to worry alot. There are ways to avoid being picked up by IDS
. After you finish scanning, you will gain a list of network nodes that exists there."Node" is an active electronic device that is attached to a network, and is capable of sending, receiving, or forwarding information over a communications channel. If you want to learn more, google it or visit http://en.wikipedia.org/wiki/Node_(networking) ...
Ok now we want to discover live hosts via scanning. This is the first action taken against your target's network. Depending on what method of scanning you use, you can be detected by IDS. Most admins will ignore detections because it happens alot unless something abnormal happens.
EDIT: TEMPORARY STOPPING POINT OF GRAMMATICAL EDITING
There are various scanner tools, e.g. nmap, superscan, and many more. There are various scan methods, some are stealthy, others are not.
Before i talk about various scanning methods, let me explain to you about TCP connections basics. When you scan your target using TCP communication, there are six TCP flags can be utilized during packet transmission(packets get transmitted during scanning process). A flag will indicate whether the sent packets are syn, ack, fin, urg, psh, or rst packets. These packets sets you in a position on how you want to communicate with the remote host. You can get different info depending on the flag you choose for the scanning.
TCP establishes three handshakes, syn, syn-ack, ack. What are they?
When you scan your target using TCP communication, you send a syn packet(syn request), and then target sends you back an ack packet with syn packet. Now, you send an ack packet to the target. So now both machines establish the connection well, like they have made a well established tunnel for a proper guaranteed communication without losing any packets during communicating with each other. A hacker can get caught easily if he uses this method to hack other systems illegally.
Hackers use non-standard combination of these six flags, which gives them info that are not normally available to the public.
Have you heard about syn flood?
syn flood is done by utilizing three handshake by sending "syn" request to the target, so the target receives a syn request and send an a syn-ack back to the originator(you). You ignore the target syn-ack request - when you ignore it, then the three handshakes is not completed, this is called half open TCP connection - In theory, when the target sends you syn-ack, the target allocates some RAM on its machine.
The amount of RAM on the target machine must be open until it gets response (ack packet) back from you because till now only two handshake has been made,so the TCP connection process is not completed yet. However, there is always a time limit for the RAM to be opened, so if 30 secs passed by & the target did not get the ack from you, the connection will abort(failed TCP handshake - timeout) & RAM will be deallocated.
The idea here is to send hell alot of packets in few secs so in 30 secs, you can send 40 million packets(lets say one packet size is 1kb) which is heavy on the RAM since the RAM might not have enough memory to carry 40 million packets. Therefore, you force the target to make half open TCP connection attempts, so definitely the target machine will stop responding to legitimate request. In other words, if you send 40 million syn requests to that remote host, it's going to allocate a hell of a lot of ram for those requests. After a while, it's going to eat up all of the ram. Thus, target system goes down. This is called syn flood attack.
In short, syn flood attack makes the system (i.e. the IP stack or kernel) chokes on the memory allocations (or simply runs out of memory) or the target application (i.e. web server) chokes on the processing load. You got it? Or not yet?! Syn flood is an old technique i just mentioned it here for illustration purposes.
General Info-: these days, SYN floods are used to make systems inaccessible. They have a limited number of half open connections, you use them all, and they can't accept any more SYNs. But again, modern software throws away old SYNs once the limit is reached. Note that different systems will behave differently.
If you interested in learning more about syn flood, visit
http://tools.ietf.org/html/rfc4987
part 2
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