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malicious encoding - mysql php
From: <biftarin () hotmail com>
Date: 2 Sep 2004 19:44:29 -0000

Hi all,

I'm currently auditing a forum running on Redhat Enterprise, Apache 1.3.27, PHP 4.3.7 and mySQL 3.23.58 .

The problem I need to solve is how to bypass this filter that blocks apostrophes.

$input = str_replace("'", "&#39;", $input)

(in case the board decodes the 2nd argument, it is ampersand hash 39)  

I have tried UTF-8 encoding ( %c0%a7 ) and the apostrophe appears in the mysql log file. 

e.g  The query in the logfile looks like this.

SELECT * FROM sessions WHERE key='invalidkey' AND member_id = '1'

This doesn't return a row. Yet when I copy and paste this query and execute it through the mysql client it returns a 
row as expected.

It looks as though the %c0%a7 isn't being filtered out by PHP but it's not being viewed as an apostrophe by mySQL even 
though it appears as an apostrophe in the mySQL log file.

If someone could help me understand this discrepancy or offer an alternative way to bypass the filter I'd really 
appreciate it.

Thanks in advance.

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