In many SQL databases, two single quotes placed consecutively and embedded
as a literal between two other single quotes are translated to a single
quote. Basically the first quote is escaping the second quote.
For instance:
print 'test''test'
shows up as
test'test
Or:
print 'test''''test'
shows up as
test''test
Looks like the code is attempting to escape quotes by translating each
single quote to two single quotes. The % are simply wildcard values for the
search.
What can you do with this? It depends. What database platform is being used?
How is the connection being made from the web server to the database, ODBC,
JDBC, ole db?
For instance, if the web server is using jdbc to connect to oracle, a
backslash '\' should escape the quote. You can try passing
aaa%\' UNION SELECT Password from dba_users WHERE USERNAME = 'SYSTEM
which should translate to:
SELECT Name FROM Users WHERE Name LIKE 'aaa%\'' UNION SELECT Password from
dba_users WHERE USERNAME = 'SYSTEM'
Try as many different escape characters as you can think of - &@^\/{}. Try
sending a backspace character after the single quote to see if it might
erase one of them but not the other, or you may even be able to backspace
over the entire statement.
Once you've escaped the quote, executing any sql statement becomes easy.
HTH,
Aaron Newman
> -----Original Message-----
> From: Penetration Testers [mailto:PEN-TEST_at_SECURITYFOCUS.COM]On Behalf
> Of Aurobindo Sundaram (+1 512 918 1390)
> Sent: Wednesday, February 07, 2001 3:08 PM
> To: PEN-TEST_at_SECURITYFOCUS.COM
> Subject: [PEN-TEST] Hacking SQL queries ...
>
>
> I have to audit a bit of code that does the following
>
> SELECT Name FROM Users WHERE Name LIKE '%input%' ORDER BY Name
>
> where input is the user-input. When I try the input 'test, the code
> generated is
>
> SELECT Name FROM Users WHERE Name LIKE '%''test%' ORDER BY Name
>
> Since I'm an SQL newbie, I'd be curious to know how someone could supply
> the appropriate input to do bad things on the SQL server - either
> in R/O or
> R/W mode
>
> If there are SQL hacking pages someplace, a link would be appreciated
>
> Thanks,
> Robin
>
Received on Feb 08 2001
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