- [Narrator] Two of the most common
authorization-based vulnerabilities
are parameter pollution vulnerabilities
and insecure direct object reference vulnerabilities.
Now, latter in the course, you're gonna learn more
about the insecure direct object reference vulnerabilities
So here, I'm gonna concentrate
in the HTTP parameter pollution vulnerabilities or HPP.
Now, HPP vulnerabilities can be introduced
if multiple HTTP parameters have the same name.
This issue may also cause an application
to interpret values incorrectly.
Basically, you, as an attacker,
can take advantage of these vulnerabilities
to bypass input validation, to trigger application errors,
and also to modify internal variable values.
HPP vulnerabilities can definitely lead
to server and client side attacks.
Now, an attacker can actually find HPP vulnerabilities
by finding forms or actions that allow user-supplied input.
Then, the attacker can append the same parameter
to a GET or a POST data, or POST request.
Now, let's take a look at the URL
that I'm showing on the screen.
So, in this case, actually store.h4cker.org.
This URL has a core string called search
and then, it also has a parameter called cars, right?
So, the attacker can actually append
the same parameter with a different value
and then submit the new request.
After that request has actually been submitted
the attacker can actually analyze
the response to identity whether
any of the values actually entered
were parsed by the application.
Sometimes this is actually necessary
to send three, you know, HTP requests
for each parameter or more, so if the response
from the third parameter is different
from the first one or the second one
then this may be an indicator of impedance
or, what we call, impedance mismatch
that could be abused to trigger
these type of vulnerabilities.