GHSA-pqg8-crx9-g8m4 BIT-typo3-2020-11069 CVE-2020-11069
Backend Same-Site Request Forgery in TYPO3 CMS
- Severity
- 8.0 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.74%
- Chance of exploitation in the next 30 days. Higher than 54.59% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Fix
- Available
- 2 packages have a fixed version
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
Affected versions
Packagist
| Package | Vulnerable | Fixed in |
|---|---|---|
| typo3/cms | >= 10.0.0, < 10.4.2 |
10.4.2 |
| typo3/cms | >= 9.0.0, < 9.5.17 |
9.5.17 |
| typo3/cms-core | >= 9.0.0, < 9.5.17 |
9.5.17 |
| typo3/cms-core | >= 10.0.0, < 10.4.2 |
10.4.2 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
typo3/cms Packagist → 10.4.2
- composer
composer require typo3/cms:^10.4.2
typo3/cms-core Packagist → 9.5.17
- composer
composer require typo3/cms-core:^9.5.17
Severity breakdown
CVSS 3.1 8.0
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-346: Origin Validation Error
The product does not properly verify that the source of data or communication is valid.
CWE-352: Cross-Site Request Forgery (CSRF)
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.
How to prevent it
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482]. For example, use anti-CSRF packages such as the OWASP CSRFGuard. [REF-330] Another example is the ESAPI Session Management control, which includes a component for CSRF. [REF-45]
- Implementation: Ensure that the application is free of cross-site scripting issues (CWE-79), because most CSRF defenses can be bypassed using attacker-controlled script.
- Architecture and Design: Generate a unique nonce for each form, place the nonce into the form, and verify the nonce upon receipt of the form. Be sure that the nonce is not predictable (CWE-330). [REF-332]
- Architecture and Design: Identify especially dangerous operations. When the user performs a dangerous operation, send a separate confirmation request to ensure that the user intended to perform that operation.
- Architecture and Design: Use the "double-submitted cookie" method as described by Felten and Zeller: When a user visits a site, the site should generate a pseudorandom value and set it as a cookie on the user's machine. The site should require every form submission to include this value as a form value and also as a cookie value. When a POST request is sent to the site, the request should only be considered valid if the form value and the cookie value are the same. Because of the same-origin policy, an attacker cannot read or modify the value stored in the cookie. To successfully submit a form on behalf of the user, the attacker would have to correctly guess the pseudorandom value. If the pseudorandom value is cryptographically strong, this will be prohibitively difficult. This technique requires Javascript, so it may not work for browsers that have Javascript disabled. [REF-331]
- Architecture and Design: Do not use the GET method for any request that triggers a state change.
- Implementation: Check the HTTP Referer header to see if the request originated from an expected page. This could break legitimate functionality, because users or proxies may have disabled sending the Referer for privacy reasons.
References
Advisories
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-68jx-f42c-7599 TYPO3 CMS - Broken Access Control in Backend and Install Tool | High | Also affects typo3/cms-core |
| GHSA-chm7-4vch-h8vr TYPO3 CMS has Broken Access Control in its Media Module | High | Also affects typo3/cms-core |
| GHSA-jh32-v29g-68pq TYPO3 CMS has Privilege Escalation & SQL Injection in its Form Framework | High | Also affects typo3/cms-core |
| GHSA-c78m-c52x-jgwp TYPO3 CMS has Insecure Deserialization via Core API | Medium | Also affects typo3/cms-core |
| GHSA-jf56-v8jc-jcc5 TYPO3 CMS has Broken Access Control in its File Abstraction Layer | Low | Also affects typo3/cms-core |
| GHSA-2j54-93q2-3hjq TYPO3 CMS has Broken Access Control in Backend API | Medium | Also affects typo3/cms-core |
| GHSA-q93m-25xv-94hh TYPO3 CMS: Broken Access Control in Media Module | Medium | Also affects typo3/cms-core |
| GHSA-qcmw-6rm2-5x78 TYPO3 CMS has Broken Access Control in its DataHandler | Medium | Also affects typo3/cms-core |
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