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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