RE: SQL injection from within a table - is it possible?

["Ofer Shezaf" <Ofer.Shezaf () breach com>]

Stored SQL injections are feasible and research has been done in that
area. The best article I know regarding what is called "second order
attacks" is
"Second order code injection attacks" by Gunter Ollmann
(http://www.nextgenss.com/papers/SecondOrderCodeInjection.pdf) 

The document "Advanced SQL Injection In SQL Server Applications"
(http://www.nextgenss.com/papers/advanced_sql_injection.pdf) refers
specifically to second order SQL injections.

Both documents are by NGSSoftware.

An interesting aspect of second order SQL injection is that many times
it can be used to overcome security filters. For example, since second
order many times implies that the string is processed twice, such
attacks can many time employ double encoding to overcome tests for
forbidden characters.

~ Ofer

Ofer Shezaf
CTO, Breach Security
Tel: +972.9.956.0036 ext.212
Cell: +972.54.443.1119
ofers () breach com
http://www.breach.com

> -----Original Message-----
> From: Burnett, Robert [mailto:burnettr () Fortrex com]
> Sent: Friday, January 07, 2005 5:38 PM
> To: Peter Bair; pen-test () securityfocus com
> Subject: RE: SQL injection from within a table - is it possible?
>
> Peter,
>
> Building on what Kevin stated, there is a flaw in the scenario you
> presented in your post.  Suppose your username was "bob", and it was
> stored in a table called "table", in a field called "name".
>
> The query:
>
> select name from table
>
> will NOT become
>
> select bob from table
>
> It will just be: select name from table.  "bob" will be the value
returned.
> Now, if you were querying for a specific username, you could do:
select
> name from table where name = 'bob', but that requires you to know
> beforehand that you are looking for "bob".
>
> Going back to your initial question about a "stored" SQL Injection
exploit,
> I suppose that if an application was pulling a value from the database
by
> doing a SELECT query and then blindly injecting that retrieved value
into
> a subsequent query, then an exploit could be performed if that stored
> value was some maliciously crafted SQL code.
>
> For example, if you somehow got the value ' OR 'a'='a into the name
field,
> and then the application retrieved that value, stored it in the
variable
> $username, and then executed the query "SELECT * from table2 WHERE
> username='$username';", the resulting query is:
>
> SELECT * from table2 WHERE username='' OR 'a'='a';
>
> And we get all the records in the table returned to us.
>
> You get the idea.
>
> Thanks.
>
> Robert Burnett
> Fortrex Technologies
> 5303 Spectrum Drive
> Frederick, MD 21703
> Toll Free: 1-877-367-8739
> Fax: 301-947-3539
> E-Mail: burnettr () fortrex com
>
>
>
> -----Original Message-----
> From: Peter Bair [mailto:peterbair100 () hotmail com]
> Sent: Thursday, January 06, 2005 8:00 PM
> To: pen-test () securityfocus com
> Subject: SQL injection from within a table - is it possible?
>
>
> Is it possible to store an SQL injection string into a MSSQL database
> table, so when the database performs an action like through a stored
proc,
> the SQL injection attack takes place?
>
> Not through the normal means of SQL injection via a web base means,
but if
> you have the means of storing the data into the table directly.
>
> Example:
> An application has a users name in a table.  Is it possible to assign
the
> users name as the SQL injection string, something like
>    name from table; exec master.xp_cmdshell "ping me"; --
>
> so when the database is running a stored procedure with a  select
clause
> like
>
>    select name from table
>
> it really is becomes
>
> select name from table; exec master.xp_cmdshell "ping me" ;-- from
table
> Of course using the SQL query analyzer on the database table, all this
> works ok.
>
> But when I insert the SQL injection string into the table, as the
name,
> and then query the table nothing happens.
>
> Is it possible or have I missed the point here?
>
> Thanks Peter.
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