bugtraq - Re: Possible phpBB <=2.0.11 bug or sql injection?

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Date: Sat, 19 Feb 2005 13:29:41 +0100
From: "kaosone+[ONE]+" <kaosone@...il.com>
To: bugtraq@...urityfocus.com
Subject: Re: Possible phpBB <=2.0.11 bug or sql injection?


On 17 Feb 2005 09:54:57 -0000, jtm297@...online.net
<jtm297@...online.net> wrote:
> 
> It seems it has something to do with the the \'s *'s and length. I am not sure if this is a big bug but I decided to try that after looking at search.php

look at 

function phpbb_clean_username($username)
{
	$username = htmlspecialchars(rtrim(trim($username), "\\"));
	$username = substr(str_replace("\\'", "'", $username), 0, 25);
	$username = str_replace("'", "\\'", $username);

	return $username;
}

the problem is in the substr;
take for exemple phpbb_clean_username("aaaaaaaaaaaaaaaaaaaaaaaa\a")

$username = htmlspecialchars(rtrim(trim($username), "\\"));
// username not changed aaaaaaaaaaaaaaaaaaaaaaaa\a
$username = substr(str_replace("\\'", "'", $username), 0, 25);
// username become  aaaaaaaaaaaaaaaaaaaaaaaa\

and the query become

SELECT user_id FROM phpbb_users WHERE username LIKE 'aaaaaaaaaaaaaaaaaaaaaaaa\' 
(notice the last ' escaped)

a quick fix is to add $username = rtrim($username, "\\") before the
function returns