RE: XPath injection doubt

From: Andy JKC (andy@inetconsulting.co.uk)
Date: Sat Sep 24 2005 - 12:28:20 EDT


As the entire query is likely in [] with Xpath, unlike sql.

You get e.g.;

(//user[name/text()=' + InsertString + '])

Where the "hi' or 1=1 or 'hey'='hello" string deals with the surrounding
''s, giving you room to inject 1=1 to return a positive.

Whereas with e.g.;

select * from [table] where username = ' + InsertString + ';

The "hi' or 1=1--" string closes the ''s, returns a positive (1=1) and then
comments following sql out (--).

Hope that helps,

Andy.

P.S. There's a decent paper at
http://www.watchfire.com/resources/blind-xpath-injection.pdf

-----Original Message-----
From: Anne Beckman [mailto:anne.beckman@gmail.com]
Sent: 24 September 2005 04:44
To: pen-test@securityfocus.com
Subject: XPath injection doubt

I am learning the XPath injection technique. To bypass authentication,
we give a string like:

hi' or 1=1 or 'hey'='hello

I noticed that the equivalent string in SQL Injection would have been
shorter:

hi' or 1=1--

I understand that XPath does not have comments, so we cannot use the
-- technique to comment out the rest of the query. But how does that
additional OR clause with 'hey'='hello solve the problem too?

Thank-you,
Anne

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