GHSA-jp5v-5gx4-jmj9 CVE-2020-8166
Ability to forge per-form CSRF tokens in Rails
- Severity
- 4.3 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 1.67%
- Chance of exploitation in the next 30 days. Higher than 76.83% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-352 Cross-Site Request Forgery (CSRF)
- Fix
5.2.4.3- Upgrade actionpack to this version or later
Description
It is possible to, given a global CSRF token such as the one present in the authenticity_token meta tag, forge a per-form CSRF token for any action for that session.
Impact
Given the ability to extract the global CSRF token, an attacker would be able to construct a per-form CSRF token for that session.
Workarounds
This is a low-severity security issue. As such, no workaround is necessarily until such time as the application can be upgraded.
Affected versions
RubyGems
| Package | Vulnerable | Fixed in |
|---|---|---|
| actionpack | >= 5.0.0, < 5.2.4.3 |
5.2.4.3 |
| actionpack | >= 6.0.0, < 6.0.3.1 |
6.0.3.1 |
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.
actionpack RubyGems → 5.2.4.3
- bundler
bundle update actionpack # Gemfile: gem "actionpack", ">= 5.2.4.3"
Severity breakdown
CVSS 3.1 4.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Weakness
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
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-6x85-j5j2-27jx actionpack Path Traversal vulnerability | High Known exploited | Also affects actionpack |
| GHSA-xrr4-p6fq-hjg7 Directory traversal vulnerability in Action View in Ruby on Rails | High Known exploited | Also affects actionpack |
| GHSA-pgm4-439c-5jp6 Rails has a possible XSS vulnerability in its Action Pack debug exceptions | Medium | Also affects actionpack |
| GHSA-vfm5-rmrh-j26v Possible Content Security Policy bypass in Action Dispatch | Low | Also affects actionpack |
| GHSA-vfg9-r3fq-jvx4 Possible ReDoS vulnerability in HTTP Token authentication in Action Controller | Medium | Also affects actionpack |
| GHSA-x76w-6vjr-8xgj Possible ReDoS vulnerability in query parameter filtering in Action Dispatch | Medium | Also affects actionpack |
| GHSA-fwhr-88qx-h9g7 Missing security headers in Action Pack on non-HTML responses | Critical | Also affects actionpack |
| GHSA-9822-6m93-xqf4 Rails has possible XSS Vulnerability in Action Controller | Medium | Also affects actionpack |
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