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"
Tuesday, June 28, 2011
►Working of SQLInjection Attacks
7:14 AM
Ravi mishra
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