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Backend Same-Site Request Forgery in TYPO3 CMS

High severity GitHub Reviewed Published May 12, 2020 in TYPO3/typo3 • Updated Feb 5, 2024

Package

composer typo3/cms (Composer)

Affected versions

>= 10.0.0, < 10.4.2
>= 9.0.0, < 9.5.17

Patched versions

10.4.2
9.5.17
composer typo3/cms-core (Composer)
>= 9.0.0, < 9.5.17
>= 10.0.0, < 10.4.2
9.5.17
10.4.2

Description

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.

Content Security Policy

Content Security Policies 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

References

@ohader ohader published to TYPO3/typo3 May 12, 2020
Reviewed May 13, 2020
Published to the GitHub Advisory Database May 13, 2020
Published by the National Vulnerability Database May 14, 2020
Last updated Feb 5, 2024

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

EPSS score

0.082%
(36th percentile)

CVE ID

CVE-2020-11069

GHSA ID

GHSA-pqg8-crx9-g8m4

Source code

No known source code

Credits

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