Re: SQLi with backslash

[Voulnet <voulnet () gmail com>]

They are probably using that mysql_real_escape_string php function,
which escapes these characters. There are many ways to bypass it, and
you can find it all over the web.

Some examples:

use char(39) <-- ASCII decimal value of ' is 39
or use the hex value. For example SELECT (0x27) <-- 27 is the hex value of '.

For example if you want to load a file, you would call
load_file('myfile'), using hex encoding you take 'myfile' with the
single quotes included and convert it to hex, then write it as
load_file(0x27..........27) with the rest of the hex values of the
filename characters filled in between.



On Wed, Jun 22, 2011 at 5:03 PM, Robin Wood <robin () digininja org> wrote:
> Hi
> I've got a scenario where both single and double quotes are being
> stripped but no other escaping appears to be being performed. The
> database is MySQL with php on top.
>
> The query that I've found SQL injection on is in the form
>
> insert into log values ('a', 'b');
>
> where I can inject in to the second parameter.
>
> If I inject a backslash then I get
>
> insert into log values ('a', 'b\');
>
> which gives an invalid SQL statement and is how the injection was
> found. Can anyone come up with a way to exploit this? If I put
> anything before the slash isn't really worth anything and if I put
> anything after then the statement becomes valid and the slash escapes
> whatever character is after it.
>
> I thought about using the slash to encode something but couldn't get it to work.
>
> The table is write only for me, I can't see any of its entries echo'ed
> back to the site anywhere so I can't go for stored XSS or anything
> like that (maybe possible but not in the time available for the test).
>
> Apart from breaking the statement I can't see a way to exploit this,
> can anyone else?
>
> Robin
>
>
>
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