Package Instance

TYPO3 Arbitrary Code Execution via File List Module
Due to missing file extensions in $GLOBALS['TYPO3_CONF_VARS']['BE'][‘fileDenyPattern’], backend users are allowed to upload *.phar, *.shtml, *.pl or *.cgi files which can be executed in certain web server setups. A valid backend user account is needed in order to exploit this vulnerability.

Derivatives of Debian GNU Linux are handling *.phar files as PHP applications since PHP 7.1 (for unofficial packages) and PHP 7.2 (for official packages).

The file extension *.shtml is bound to server side includes which are not enabled per default in most common Linux based distributions. File extension *.pl and *.cgi require additional handlers to be configured which is also not the case in most common distributions (except for /cgi-bin/ location).

Backend Same-Site Request Forgery in TYPO3 CMS
> ### Meta
> * CVSS v3.1: AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
> * CWE-352
> * CWE-346

### Problem
It has been discovered that backend user interface and install tool are vulnerable to same-origin 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-origin 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 3rd party extension - e.g. file upload in a contact form with knowing the target location.

The attacked victim requires an active and valid backend or install tool user sessions at the time of the attack to be successful.

### Solution
Update to TYPO3 versions 9.5.17 or 10.4.2 that mitigates the problem described.

### Additional Considerations

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 by again by the acting user with 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](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy) tell (modern) browsers how resources served a particular site are handled - it also it 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 fileadmin/.htaccess
<IfModule mod_headers.c>
	Header add Content-Security-Policy "default-src 'self'; script-src 'none';"
</IfModule>
```

### Credits
Thanks to Matteo Bonaker who reported this issue and to TYPO3 security team member Oliver Hader who fixed the issue.

### References
* https://typo3.org/security/advisory/typo3-core-sa-2020-006

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
In Bootstrap, XSS is possible in the data-target property of scrollspy.

TYPO3  SQL Injection in low-level Query Generator
An issue was discovered in TYPO3 before 8.7.30, 9.x before 9.5.12, and 10.x before 10.2.2. Because escaping of user-submitted content is mishandled, the class QueryGenerator is vulnerable to SQL injection. Exploitation requires having the system extension ext:lowlevel installed, and a valid backend user who has administrator privileges.

Code Injection
Arbitrary Code Execution and Cross-Site Scripting in Backend API.

TYPO3 Information Disclosure in User Authentication
It has been discovered that login failures have been logged on the default stream with log level "warning" including plain-text user credentials.