=======================================================================
title: Multiple Vulnerabilities
product: flatCore CMS
vulnerable version: < 2.0.0 Build 139
fixed version: Release 2.0.0 Build 139
CVE number: CVE-2021-23835, CVE-2021-23836, CVE-2021-23837, CVE-2021-23838
impact: High
homepage: https://flatcore.org/
found: 2020-11-20
by: Yew Chung Cheah (Office Singapore)
Calvin Phang (Office Singapore)
SEC Consult Vulnerability Lab
An integrated part of SEC Consult, an Atos company
Europe | Asia | North America
https://www.sec-consult.com
=======================================================================
Vendor description:
-------------------
"flatCore is based on PHP and PDO/SQLite. The Core is as
minimalistic as
possible, but can be easily extended by the modular structure. If
you are
looking for a solution to edit your website live and with ease,
flatCore
may be your buddy."
Source: https://flatcore.org/
Business recommendation:
------------------------
The vendor provides an updated version which should be installed
immediately.
An in-depth security analysis performed by security
professionals is highly
advised, as the software may be affected from further security
issues.
Vulnerability overview/description:
-----------------------------------
1) Reflected Cross-Site Scripting (Authenticated user)
(CVE-2021-23838)
A reflected cross-site scripting vulnerability was identified in
the 'media_filter'
HTTP request body parameter for the 'acp' interface. The affected
parameter
accepts malicious client side script without proper input
sanitization. For
example, a malicious user can leverage this vulnerability to steal
cookies
from a victim user and perform a session hijacking attack which may
then lead to
unauthorized access to the site.
2) Stored Cross-Site Scripting (Authenticated user)
(CVE-2021-23836)
A stored cross-site scripting vulnerability was identified in the
'prefs_smtp_psw'
HTTP request body parameter for the 'acp' interface. An admin user
can inject
malicious client side script to the affected parameter without any
form of
input sanitization. The injected payload will be executed in the
browser of a
user whenever one visits the affected module page.
3) Local File Disclosure (Authenticated user)
(CVE-2021-23835)
A local file disclosure vulnerability was identified in the
'docs_file'
HTTP request body parameter for the 'acp' interface which can be
exploited with
admin access rights. The affected parameter which retrieves the
contents of the
specified file was found to be accepting malicious user inputs
without proper input
sanitization, thus leading to retrieval of backend server sensitive
files, for
example /etc/passwd, sqlite database files, PHP source code
etc.
4) Time Based Blind SQL Injection (Authenticated user)
(CVE-2021-23837)
A time based blind SQL injection was identified in the
'selected_folder'
HTTP request body parameter for the 'acp' interface. The affected
parameter
which retrieves the file contents of the specified folder was found
to be
accepting malicious user inputs without proper input sanitization,
thus leading
to SQL injection. Database related information can be successfully
retrieved.
Proof of concept:
-----------------
1) Reflected Cross-Site Scripting (Authenticated user)
(CVE-2021-23838)
An authenticated admin user can exploit this vulnerability by
manipulating
the 'media_filter' parameter found in the Files/ Manage Files
module.
URL : http://$HOST/acp/acp.php?tn=filebrowser&sub=browse
METHOD : POST
PARAMETER : media_filter
PAYLOAD :
aaa%3cscript%3ealert(document.cookie)%3c%2fscript%3ebbb
2) Stored Cross-Site Scripting (Authenticated user)
(CVE-2021-23836)
An authenticated admin user can exploit this vulnerability by
manipulating
the 'prefs_smtp_psw' parameter found in the System/ E-Mail
module.
URL : http://$HOST/acp/acp.php?tn=system&sub=mail
METHOD : POST
PARAMETER : prefs_smtp_psw
PAYLOAD :
'%3e%3cscript%3ealert(document.cookie)%3c%2fscript%3eaaabbb
3) Local File Disclosure (Authenticated user)
(CVE-2021-23835)
An authenticated admin user can exploit this vulnerability by
manipulating
the 'docs_file' parameter found in the help module.
URL : http://$HOST/acp/acp.php
METHOD : POST
PARAMETER : docs_file
PAYLOAD :
%2E%2E%2F%2E%2E%2F%2E%2E%2F%2E%2E%2F%2E%2E%2Fetc%2Fpasswd
4) Time Based Blind SQL Injection (Authenticated user)
(CVE-2021-23837)
An authenticated admin user can exploit this vulnerability by
manipulating
the 'selected_folder' parameter found in the Files/ Manage Files
module.
URL : http://$HOST/acp/acp.php?tn=filebrowser&sub=browse
METHOD : POST
PARAMETER : selected_folder
PAYLOAD : %' AND
8483=LIKE('ABCDEFG',UPPER(HEX(RANDOMBLOB(500000000/2)))) AND
'eJQr%'='eJQr
Vulnerable / tested versions:
-----------------------------
flatCore CMS version 2.0.0 (Build 122) has been tested, which was
the latest
version available at the time of the test. Previous versions may
also be affected.
Vendor contact timeline:
------------------------
2020-12-14 | Contacting vendor through
2020-12-17 | Advisory sent to the vendor
2020-12-31 | Requesting status update from vendor
2021-01-05 | Vendor replied that the reported issues have been
fixed in
version 2.0.0 (Build 139) released at their official GitHub
page
2021-01-13 | Release of security advisory.
Solution:
---------
The fixed version 2.0.0 (Build 139) is available for download
at:
https://github.com/flatCore/flatCore-CMS
Workaround:
-----------
None
Advisory URL:
-------------
https://sec-consult.com/vulnerability-lab/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SEC Consult Vulnerability Lab
SEC Consult, an Atos company
Europe | Asia | North America
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EOF Yew Chung Cheah, Calvin Phang / @2021
