Hacking It: part 3 how to hack websites
Application Vulnerabilities: some examples of application vulnerability, buffer overflow, weak authentication mechanisms, poor data validation(the most common one), and poor error checking.

ALRIGHT, to discover these vulnerabilities on the target machine you need to do vulnerability assessment. This can be done in two ways, manually or automatically. Manually means you try to discover a vuln. by yourself which eventually you will have vuln. that nobody else knows it & you can use it for yourself or publish it to security sites. Automatically means you rely on a tool that searches for vulns in the target machine, this tool has a database full of vulns. so this 'tool' will only inform you the vulns found in the target machine by relying on 'its' database. We are going to talk about auto vulnerability assessment. The most common & wonderful tool is Nessus, its free open source code!

Alot of common sense comes into play when analyzing vulns, for example you do not look for a database vulnerability in a webserver, things like that. Another resources, OVAL - gives you a good and basic foundation of vulns assess. methodology, FrSIRT - keeps track of vulns and make exploits of these vulns, you can join a paid subscription and then browse vulns avaialbe in their database and download exploits this is a good source for hacking or security, and websites for posting exploits such as milw0rm, hacking sites.

Lets have a closer look at nessus tool, nessus is client/server architecture. The process of setting it up is cumbersome. Nessus have about 9000 plugins, therefore it takes time to peroform the assessment. Results can be reviewed in a report. The report includes the vulnerabilities found on the target machine with a short description about the vulnerability.

Note: you can enable several plug-ins in plugin tab. You can specify range of ports through scan options. To specify the target, you should go to the target tab.

Once we have done the vulnerability assessment, and knew what vulnerabilities exit. We start gathering exploits of the found vulnerabilities to penetrate the system.

Lets talk about penetration and access! After all information we have gathered previously, its the time to break the system with the exploits you have.

Its the time to stop gathering information and start breaking into system. The ultimate goal is to gain the highest level of permissions. Try to use undiscovered techniques and methods. Think out of the box!

Some of exploits that enable penetration are:

*Buffer overflows
*Stack exploits
*Web vulnerabilities
*Services/apps that allow unauthenticated access.

Aside from the standard methods of penetration, lets see an penetration methods, here are some examples:

*SQL Injection - ability to change queries in the application before its sent into database.

*Application Error Handling - this can result DoS. Probably one of the most common vulnerability you can find in corporate arenas.

*Directory Traversal - browse directories you should not be able to do so on.

*Malformed Packets - one of the more difficult methods of penetration, requires very extensive knowledge of how TCP packets are assembled and disassembled. But once you get used to it, its probably the most effective ways of hacking.

*Bypassing Access Controls - password cracking is most common means of accessing systems.

*Social Engineering - i guess you know what it means.

*Sniffers - take passwords right off the wire, alot of protocls and application such as http & ftp communicate parrwods over the wire in plain text.

*Session hijacking - it is similar to sniffers, but you don't gain a password because we take off the entire session, hijack the victim's session & act as you are him.

Usually when you get passwords, you get it encrypted, or hashed or hidden in some way or another. Password cracking can be done in several ways, examples:

*Brute Force Attack - Every password, can and will be broken by brute force attack. It is about the time. Depends on the size of the password.

*Dictionary Attack - less effective than brute force, relies on list of words or phrases.

*Hybrid Attack - combination of different tools. It is a combination of effectivence of brute force and dictionary attacks & often using other attack mechanisms, such as cryptanalysis attack (one of the hybird attack).

You should know that when you do sniffing, you often get usernames & passwords in plain text. However, you can get encrypted passwords from sniffing as well. You will need to use of the cracking techniques discussed above. Sometimes cracking an encrypted passwords can take secs, hours, days, months, or even more!!!

There is a great software called "Cain & Abel", it sniffs passwords from the wire, cracks it, etc. Once you install it, go to sniffers tab, then move to the found passwords in cracker tab to see what you have got! There is lots to it. You should know these techniques as a security person cause if you don't know it, a black hat will take care of it.

Now, assume we already have hacked the system. We will try to do different things, such as getting the root, etc. Penetration & compromise got some differences in the meaning. Hacking into system does not mean you have compromised(taking the full control - take over) the system. After you penetrate the system, you can grab the session between client and server, e.g. you keep listening on login sessions, so when the remote user login to google, the session be dropped to you, once you get the session, the remote user won't be able to get into his account he/she will see at page goes blank(disconnected), so he/she may think its a problem in a connection, thus he/she tries to login again & everything works fine! BUT you already got his session, you won't have to go through login page when you want to see his/her email inbox, cause its already among the whole session you have taken.

Another way to do this, lets say the attacker has compromised the user's system, thus the attacker can let the session drop on his machine, then he takes the session, reads and saves it. After that, he redirects the user to the server, this step will make everything works ok like nothing wrong happen.

Lets see an example of the above explained steps, after attacker installs "Cain & Abel" application, he moves to "attack base system" & click the sniffer button at the top & click the yellow button(APR Poisoning Button) besides the sniffer button. This APR Poising button trick the attacked system to talk to the attacker instead of normally who it talks to. For testing purposes, go and add various system addresses(IP's) to the list. Let say one of the user amongst those targeted IP's logon into 'google', at the authentication process you will notice varies pieces of info comes to you. You are gathering info by getting into the middle of the communication process. Now view the files you have got in the list, you can see among the lines the username & password of the users' 'google' account in plain text! So how dangerous this can be to your privacy :-/! So be careful....

Once the hacker gains access to the system. He aims for admin(root) access. He moves up from guest level, to user level, up to root level. Owning the box, means take the system & prevent the admin from controlling the system, as well as preventing other hackers from getting in. So you hackers usually move on from the regular level, to the admin level so they can have full control. A hacker needs privilege escalation to compromise the system well. Some exploits allow buffer/stack overflows to obtain admin access. All it takes is a guest user, then a hacker can perform exploitations locally & there he goes to the root.

At this point, we did everything up to owning the box. Now our goal is to protect our access. Thus, we want to maintain our access to that hacked system, so we can use it later. You can maintain a system by using such tools, backdoor accounts, backdoor software programs, rootkits, etc. These tools help you maintain access. Some hackers own the box close all other accounts except his account, so the security person shut the system down, reformat the system and start over again.

By doing this, hacker account will be gone. Once we ensure we have maintained our access to the system, then we want to expand ourselves to other parts of the network. Remember, if you do not do this on your own network, somebody else will take care of it. If he does, i do not think you will be too happy! Once you got an access, and could maintain it successfully. You want to prevent detection or loss of access. There are several methods to maintain access, such as rootkits, OS exploits, erase tracks, install trojans that make you access backdoor, enable null sessions (webmaster usually go to the registry & disable null sessions to keep that vuln. from being exploited, webmasters usually do it once & do not get back to it. You can go there & enable it - NOTE: by enabling null sessions you can give other hackers a chance to hack too), and many more.

There different ways of system compromise, system compromise usually depends on your goal, examples of system compromising are root access(ultimate goal), data access/theft, DoS, and many more. Keep in mind, compromised systems can be detected after a while.

Now after a hacker breaks into the system, he tries to portect what he has hacked & erase his tracks. During the attack process try not to be detected so the webmaster don't shut the server off, as well as do not forget to erase your tracks, e.g. you dont want the webmaster to see lots of failed logon in the log files, so you erase tracks to prevent future detection. Typically, get in the network as a shadow or ghost.

There are many method to evade those IDS so they don't cut off your attack stream. Common methods for evading defenses might be by fragmenting packets(some programs do that e.g. fragroute), port redirectors, encoders(change the flow, the look, and feel of various traffics to pass firewall). After you get in and deceive defenses, you want to go to the log files and erase your tracks. Remember: sometimes you get in a user account then you get into a root by changing permissions of the user account, so you have to remember to set this user permissions back to as it was, things like that - you know what i mean, put yourself in a hackers shoe. Don't delete the whole log files, this can make the security person more suspicious. We want to leave everything as it was so nobody can get a feel that an intruder was here.

To be safe, you should know where your actions are recorded, delete log files and other evidences that can get you caught, steganography(google it), and evading IDS & firewalls. All actions are recorded in some place on the system or the network. Assume IDS detects you, what do security persons do? Usually when you get detected, they may cut off all the ways for you so you don't get a chance to penetrate, they probably going track you down, or they may decide let you go but watch you the entire time.

Where are your actions recorded & what things can let security person knows that you hacked his system? they are recorded in log files for various applications(e.g. IIS & Apache log files), file access times(note: there are tools for hackers that allow you to modify file access time), windows registry entries, hacker tools left behind (be aware of the residual configuration you have left behind - make sure you set all the configurations back to as it was), OS performance stats, IDS, proxy servers(make sure how you send and receive data. If you are going to use proxy server, set up a permanent tunnel through the proxy to the remote host that is compromised), and firewalls(usually very rich with logs).

There are various types of IDS, IDS can set anywhere in the network. There are network based IDS, host based IDS, and application based IDS.

Deleting evidences of your hack is extremely difficult, it requires you have a very high knowledge of the system you are trying to compromise(all the prior steps we did, such as scanning, foot printing, etc will be handy to compromise the system). It is easy to cover the known log files, such as web logs, firewall, IDS logs, etc. However, it is important to know how the default logs work. Highly skilled hackers, study the target well & take the time in fingerprinting & footprinting everything properly. It may take him up to one week before he hacks the target, but when he penetrates his job is done more smoothly & quietly. Unlike, the other ones who are just using some tools to break the system as fast as possible without studying the target well.

It is possible to delete log files! It is simple but usually requires admin access. Some files/logs may be deleted automatically with reboot. Don't delete log files, it brings up suspicion. If you do so, the security person can indicates very clearly that a hacker broke into the system.

Most common way of hiding your tracks is by using a rootkit. Rootkit is set of tools used by an attacker after the attacker gets the root-access to system. Rootkits conceals(to keep from being observed) attacker activities on the hacked system. Once rootkit set on the system, its practically impossible to rid of it because rootkit uses technology, called "hooks", that usually most of the time embed itself into various components of OS & effectively the OS going to be a toaster when the rootkit is all set and done. Security person has to rebuild his machine when rootkit is detected after we properly investigate it.

Steganography its about hiding a file into another file. Like hiding a malware into a normal software which makes it difficult for firewall or AV to detect the malware. Thats the basic concept of Steganography. There are alot of tools out there allow us to hide files inside another files.

You can evade IDS & firewalls by using random slow stealth scanning technique so traffic goes unnoticed, this takes longer to scan but makes detection more difficult. Try to use non-standard techniques, think outside the box.

Remember: not everyone out there is a security expert. To secure your system well, you need to put yourself in a hacker set of mind.

By now, you have learned the basic methodology that hackers use to break into the system. Anyhow, lets take a closer look on hacking techniques, such as encryption, sql injection, sniffers, and many more.

Encryption: files can be encrypted in a storage. Communication channels can be encrypted as well, communication channel encryption encrypts the entire communication path, so all traffics sent and received are encrypted, e.g. SSL technology encrypts the entire communication path. There are many ways hackers get away of encrypted traffic & get info in not encrypted form. If you are using your own encryption method, you always should test your encryption for crackability before you use it officially.

Sniffers: sniffers is a common tool used by hackers. Sniffers listens on any traffic that goes through the wire of the target system, listens ins and outs traffics. Promiscuous mode is a mode that is listening for any traffic that goes through the wire. Standard promiscuous mode sniffer is a basic technique. There are more advanced techniques other than promiscuous mode. Sniffing enables the attacker to pick up a plain text, and other sensitive data that goes 'from' or 'to' the target. Sniffers record captured traffic, then after you sniff you can go offline & start analyzing that captured traffic. Popular sniffers are ethereal, etherape, ettercap, and network monitor(for Win OS only - not so effective).

Wireless Hacking: this is a new technology & starts taking place nowadays. Easy to setup, but not frequently secured since not many people understand the security configuration, so they decide not to set it up or set it up poorly. There are various tools that detect wireless networks, popular war driving software are Netstumbler, Airsnort, Airopeek, Kismet, and many more. What is war driving? google it!

SQL Injection: sql injection is a technique that allows an attacker to steal a valuable database information. This attack relies on poor data validation and poor error checking.

Buffer Overflows: buffer overflow is common, the cause of buffer overflow is poor coding. Buffer overflows might be noticed while coding. Buffer overflow happens when the programmer does not clearly define boundaries on buffers or variables. We use out of bound data to insert malicious code or execute command on the remote host. Buffer Overflows can cause programs to freeze or lockup, can cause machine to crash, or let you use exploits & leads you to compromise the system. To build buffer overflows, you need a good programming skills, good knowledge of stack and buffer vulns.

You need to have the ability to research, analyze vulns & apply the exploit to achieve what you want. Buffer overflow is a very common & hard to produce an application with no buffer overflows at all. There is nothing programmers can do about it, they just need to write the code with security mind of set. If unexpected buffer overflow appears later by chance, programmers will have to fix it. Programmers should test their code from vulnerabilities as much as they can before they publish the application.

Rootkits: it is a common hacker technique. Rootkit is malicious program that replaces components of OS. It does a stealth job. Rootkit requires root permission, so you can install it. Linux rootkits are common & you can find them everywhere, unlike Windows. It is very hard to detect a rootkit because it embeds itself so deeply into the target system. Removing rootkit from a system is very hard too, if the security person tries to remove the rootkit out of the system, he will destroy the system since the rootkit is embedded so deeply into the system(into components of OS). The good solution is to format the whole system & install it again.

Spoofing: the word spoofing defined as making yourself appear as somebody else. Examples of spoofing, you can spoof an IP address and make yourself appear to be somewhere else, MAC addresses, and emails(very simple to spoof, you send an email to somebody by changing the headers, and things like that). Spoof usually relies on poor implementation of TCP/IP itself or poor implementation of applications. Tools that are used for spoofing differs from one platform to another. Example of the tools, IP spoofing utilities, MAC address modifiers, etc. Spoofing is more into using your skills rather than using a tool.

Denial of Service (DoS): DoS is very common. The ultimate idea is to prevent legitimate users from using the system. Running DoS is very simple, you don't gain anything from doing DoS. Hackers do it to threat companies, things like that. Many methods/level of DoS attacks exist. Examples of some ways of to DoS, ping of death, Windows size overflow, smurf, teardrop attacks, and many more. There are lots of different ways to do it!

Web Hacking: web hacking is the most popular attacks. It is based on hacking individual sites, servers, or components based on the website. First step a hacker takes is, enumerate services(applications) on target machine, and then determine what webserver software(apache, IIS, etc) is running on the target system. After that, the hacker exploits against vulns. found in the target system. It will be easier to hack if the hacker knows the version of the service/software running.

A webserver attack leads to deeper penetration on the network(move into the target's internal network). Popular attack methods are xxs(cross-site scripting), IIS DLL vulnerabilities(IIS is very commonly exploited), directory traversal, unicode attack, and many more.

What is Unicode attack?
here is quick rough description about Unicode attack, lets say you want to pass space into a URL. If you put a space in URL, webserver will not take your URL, webserver will consider the url is invalid. Thus, if you want to put spaces among the URL, you should put the number 20 in a place of the space(number 20 represents the space), so when the URL goes to the webserver, the webserver says Ok! thats a valid URL, lets process it and so it does. Unicode attack uses this technique in a non-standard(bad way) way to attack the webserver. Thats a quick explaination about unicode attack.

I'm already about to finish this tutorial, i will just talk about popular tools in a brief manner. I will start with namp.

Nmap is the most popular hacker tool outhere. Linux command line nmap works better and is supported better. Nmap comes with ping utility, port scanning utility, service enumeration & OS fingerprinting.

SuperScan is a windows based tool developed by foundstone Inc. Its easy to use it & a good tool for Windows.

Nessus is used for vulnerability assessment. It is an open source software kit, with commercial version available as well. Nessus uses client/server architecute. Server will be installed on a central location. Nessus comes in GUI & command line interface. Nessus uses database that carries latest current exploits for all types of OS & application. Databases in nessus are called plug-ins, hundrends of vulnerability plug-ins exist and are updated daily to include latest exploits. Nessus requires high level of knowledge to use the tool very effeciently. You can go out to the web and download an exploit and then add it to the database. Nessus can take quite long time to do vulnerability assessment.
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