►Working of SQLInjection Attacks

SQl injection is a

vulnerability that allows an

attacker to influence the

queries that are passed to

the back-end database. It

has been present since the

time databases have been

attached to the web

applications. Before

understanding the how

SQL injection attacks we

need to understand the

Simple Three Tier

Architectureor a Four Tier

Architecture.This will clear

your basics and give you a

rough idea of how

database-driven web

applications work. Three

Tier Architecture In a

simple three tier datbase-

driven architecture the

three layers that are used

are:- 1. Presentation Tier

(Browsers) 2. Logic Tier 3.

Storage Tier(Database) The

three tier architecture

follows a linear relationship

i.e Presentation Tier

connects to the Logic Tier

and theLogic Tier connects

to the Storage Tier

Presentation Tier <–> Logic

Tier <--> Storage Tier

Suppose you connect to

the http://

www.website.com using

his web browser.This is

your presentation tier.Now

the web server residing in

the logic tier will load the

script for the entered url

and will pass it to the

scripting engine which will

parse and execute the

script.It will also open a

connection to the database

i.e Storage Tier .It will

perform the queries and

the data from the database

is transferred to the logic

tier which will now convert

into HTML which is

rendered by the Browser.

Four Tier Architecture In

Four Tier Architecture an

layer of Application Server

is inserted between a web

server and the database. 1.

Presentation Tier(Browsers)

2. Logic Tier 3. Application

Tier 4. Storage Tier

(Database) In four tier

architecture the connection

to the database is opened

by application server which

has Application

Programming Interface

(API) that implements the

business logic before

transferring the data to the

Logic tier. Presentation

TierLogic Tier Application

Server Storage Tier

Working Of SQL Injection

SQL injection can be used

using various methods.In

this page I will explain to

the basic concepts behind

the SQL injection. Suppose

you are on a shopping site

and you have selected the

option of showing all the

accessories that costless

then 200$ and its Url is like

http://

www.shoppingsite.com/

products.php?val=100 To

test this website for SQL

injection try appending

your SQl injection

commands in the val

parameter ‘OR ‘1’=’1 http://

www.shoppingsite.com/

products.php?

val=100’OR’1’=’1 If the

above injection works and

shows the list of all the

accessories then the

website is vulnerable to this

type of SQL injection This

means that at the backend

the script will be executed

as shown: SELECT *

FROMProductstbl

WHEREPrice<’200.00’ OR

‘1’=’1’ ORDER

BYProductdescription As

the condition 1=1 so this

will give you list of all the

products How this SQL

injection Attack Can Be

Harmful Suppose a website

uses the following url for

logging into admin panel

http://www.website.com/

cms/login.php?

username=saini&password=go

now if the above website is

vulnerable to the SQL

injection as mentioned in

the above example then by

entering any username and

password in the url you

can login http://

www.website.com/ms/

login.php?

username=dnt&password=dnt’OR’1’=’1

so you will just login

without valid username

and password to the

admin panel of a website.

NOTE:"The Above

Information is Only For

Education purposes and to

make our Users beware of

Threats,plz DO NOT Misuse

your Knowledge"