88%
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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/.
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/.
CVSS 3.1 Base Score 8.8. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).
CVSS 2.0 Base Score 6.8. CVSS Attack Vector: network. CVSS Attack Complexity: medium. CVSS Vector: (AV:N/AC:M/Au:N/C:P/I:P/A:P).
This example PHP code attempts to secure the form submission process by validating that the user submitting the form has a valid session. A CSRF attack would not be prevented by this countermeasure because the attacker forges a request through the user's web browser in which a valid session already exists.
The following HTML is intended to allow a user to update a profile.
</form>profile.php contains the following code.
}//if the session is registered to a valid user then allow update
exit;// Redirect user to login page// The user session is valid, so process the request// and update the information
echo "Your profile has been successfully updated.";// read in the data from $POST and send an update// to the databaseThis code may look protected since it checks for a valid session. However, CSRF attacks can be staged from virtually any tag or HTML construct, including image tags, links, embed or object tags, or other attributes that load background images.
The attacker can then host code that will silently change the username and email address of any user that visits the page while remaining logged in to the target web application. The code might be an innocent-looking web page such as:
</form>form.submit();// send to profile.phpNotice how the form contains hidden fields, so when it is loaded into the browser, the user will not notice it. Because SendAttack() is defined in the body's onload attribute, it will be automatically called when the victim loads the web page.
Assuming that the user is already logged in to victim.example.com, profile.php will see that a valid user session has been established, then update the email address to the attacker's own address. At this stage, the user's identity has been compromised, and messages sent through this profile could be sent to the attacker's address.
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