Composer Typo3/cms-core vulnerabilities

The referrer enforcement introduced with TYPO3-CORE-SA-2020-006 (CVE-2020-11069) became ineffective in TYPO3 v13.0, where TYPO3 CMS started serving the backend and Install Tool applications from the site's main entry script instead of the dedicated typo3/ directory. Whether a request originated from the backend or Install Tool itself was determined by comparing the referrer against the directory of the entry script, which since then is the site root. As a consequence, requests originating from any script running on one of the TYPO3 instance's own domains, such as a frontend page, were accepted by backend routes and Install Tool endpoints. Attackers able to execute JavaScript on one of those domains, for instance by exploiting a cross-site scripting vulnerability, could invoke these endpoints via Fetch/XHR with the privileges of an authenticated victim's user session. This issue affects TYPO3 CMS versions 13.0.0-13.4.33 and 14.0.0-14.3.5.

In TYPO3 CMS 9.0.0 through 9.5.16 and 10.0.0 through 10.4.1, it has been discovered that the backend user interface and install tool are vulnerable to a same-site request forgery. A backend user can be tricked into interacting with a malicious resource an attacker previously managed to upload to the web server. Scripts are then executed with the privileges of the victims' user session. In a worst-case scenario, new admin users can be created which can directly be used by an attacker. The vulnerability is basically a cross-site request forgery (CSRF) triggered by a cross-site scripting vulnerability (XSS) - but happens on the same target host - thus, it's actually a same-site request forgery. Malicious payload such as HTML containing JavaScript might be provided by either an authenticated backend user or by a non-authenticated user using a third party extension, e.g. file upload in a contact form with knowing the target location. To be successful, the attacked victim requires an active and valid backend or install tool user session at the time of the attack. This has been fixed in 9.5.17 and 10.4.2. The deployment of additional mitigation techniques is suggested as described below. - Sudo Mode Extension This TYPO3 extension intercepts modifications to security relevant database tables, e.g. those storing user accounts or storages of the file abstraction layer. Modifications need to confirmed again by the acting user providing their password again. This technique is known as sudo mode. This way, unintended actions happening in the background can be mitigated. - https://github.com/FriendsOfTYPO3/sudo-mode - https://extensions.typo3.org/extension/sudo_mode - Content Security Policy Content Security Policies tell (modern) browsers how resources served a particular site are handled. It is also possible to disallow script executions for specific locations. In a TYPO3 context, it is suggested to disallow direct script execution at least for locations /fileadmin/ and /uploads/.