Re: SQL injection (or not?)

["Mike Klingler" <whitehatguru () gmail com>]

On 8/8/06, rr () neo dtcom lv <rr () neo dtcom lv> wrote:

> I'm having weird situation with sql injection (I guess). Unfortunately there is
> no error message displayed - blind injection, so all that I know - query is
> valid or not.
The first step I take when working on a blind SQL injection is to see
if I can get it to respond with a "YES' and a "NO" query.  When I
suspect a blind sql injection I will try to alter the pages content
via the injection.

For example.  If a site will list products by number doing a search
for the query productid='1' OR '1' = '1', should return the entire
list of products.  So potentially we could have a page return will an
entire list of products instead of just one.  If I was able to get the
query productid='1' AND '1'='1' to return a page will only the one
item then I would have what I call a "YES" query.  Since the item we
are questioning ( 1=1) is true.  If you were able to get the request
productid=1' AND '1'='0' to return a page with no listing, then you
would have found the answer to a "NO" query.

Some times they will check for a query that returns no rows and send
that to a generic error page.  So at times you may only get a Yes page
and a NO/error page.  Which prevents you from being able to
distinguish between a NO and a bad query.

In the end you would have the ability to put in queries like
productid='1' AND substr(@@version,1,1) > 'g' and learn if the first
character of the version was greater than G based on if the YES page
was returned or the NO/Error page.

> script.aspx?parameter=' and 'a'%2b'a'='aa
> no result, aparently query is invalid, so it is not MSSQL, kind of
>
> script.aspx?parameter=' and concat('a','a')='aa
> returns page, sql query turns out to be valid, MySQL??
>
> meanwhile
> script.aspx?parameter=' and concat('a','a','a')='aaa
> no result, so it is not MySQL
>
> also I know that database should be MSSQL
>
> concat is first function I found to work. Maybe it is not sql injection? What
> else could it be?
>
> rr



--
Michael Klingler, CISSP
SecurityMetrics Penetration Tester

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