Common website hacking methods!



A large number of websites a hacked daily. Its seems like there is a cyber war taking place. Today i will show you those common methods using which these sites are hack. Lets see an overview below :

95% of web applications have following vulnerabilities:

•Cross-site scripting (80 percent)

•SQL injection (62 percent)

•Parameter tampering (60 percent)

•Cookie poisoning (37 percent)

•Database server (33 percent)

•Web server (23 percent)

•Buffer overflow (19 percent)

Some are explained below, I will post details later..
1. Cross site scripting :
Cross-site scripting (XSS) is a type of computer security vulnerability typically found in web applications that enables malicious attackers to inject client-side script into web pages viewed by other users. An exploited cross-site scripting vulnerability can be used by attackers to bypass access controls such as the same origin policy.

I recenlty cleared XSS in this post :
http://www.hackersthirst.com/2011/01/cross-site-scripting-using-hole-to-hack.html

2.SQL injection

SQL injection is a code injection technique that exploits a security vulnerability occurring in the database layer of an application. The vulnerability is present when user input is either incorrectly filtered for string literal escape characters embedded in SQL statements or user input is not strongly typed and thereby unexpectedly executed.

3.Parameter tampering
The Web Parameter Tampering attack is based on the manipulation of parameters exchanged between client and server in order to modify application data, such as user credentials and permissions, price and quantity of products, etc. Usually, this information is stored in cookies, hidden form fields, or URL Query Strings, and is used to increase application functionality and control. 

Example:
Leta take an example in which, a web application that permits a user to select his profile from a combo box and debit the account:
http://www.attackbank.com/default.asp?profile=741&debit=1000
In this case, an attacker could tamper with the URL, using other values for profile and debit: 


http://www.attackbank.com/default.asp?profile=852&debit=2000
 This can be done by various addons available for mozilla.

Cookie poisoning:
Cookie Poisoning attacks involve the modification of the contents of a cookie (personal information stored in a Web user's computer) in order to bypass security mechanisms. Using cookie poisoning attacks, attackers can gain unauthorized information about another user and steal their identity.
This involves the use of cookie stealing script and an addon or software to replace these cookies with yours.

Buffer overflow:
In computer security and programming, a buffer overflow, or buffer overrun, is an anomaly where a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory. Buffer overflows can be triggered by inputs that are designed to execute code, or alter the way the program operates. This may result in erratic program behavior, including memory access errors, incorrect results, a crash, or a breach of system security. They are thus the basis of many software vulnerabilities and can be maliciously exploited.

The principle of exploiting a buffer overflow is to overwrite parts of memory that are not supposed to be overwritten by arbitrary input and making the process execute this code. To see how and where an overflow takes place, look at how memory is organized. A page is a part of memory that uses its own relative addressing, meaning the kernel allocates initial memory for the process, which it can then access without having to know where the memory is physically located in RAM.