How websites are being hacked - Part 1

SQL Injection

SQL Injection involves entering SQL code into web forms, eg. login fields, or into the browser address field, to access and manipulate the database behind the site, system or application.

When you enter text in the Username and Password fields of a login screen, the data you input is typically inserted into an SQL command. This command checks the data you've entered against the relevant table in the database. If your input matches table/row data, you're granted access (in the case of a login screen). If not, you're knocked back out.

The Simple SQL Injection Hack

In its simplest form, this is how the SQL Injection works. It's impossible to explain this without reverting to code for just a moment. Don't worry, it will all be over soon.

Suppose we enter the following string in a Username field:

' OR 1=1

The authorization SQL query that is run by the server, the command which must be satisfied to allow access, will be something along the lines of:

SELECT * FROM users WHERE username = ‘USRTEXT '
AND password = ‘PASSTEXT’

...where USRTEXT and PASSTEXT are what the user enters in the login fields of the web form.

So entering `OR 1=1 -- as your username, could result in the following actually being run:

SELECT * FROM users WHERE username = ‘' OR 1=1 -- 'AND password = '’

Two things you need to know about this:
['] closes the [username] text field.

'' is the SQL convention for Commenting code, and everything after Comment is ignored. So the actual routine now becomes:

SELECT * FROM users WHERE username = '' OR 1=1

1 is always equal to 1, last time I checked. So the authorization routine is now validated.

username field examples:

• admin'--
• ') or ('a'='a
• ") or ("a"="a
• hi" or "a"="a

... and so on.

Let's hope you got this.

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