CVE-2021-4400

Better Search <= 2.5.2 - Cross-Site Request Forgery Bypass

2021-03-01 00:00
Jerome Bruandet

Strategic Overview

Status
Patched in 2.5.3
Affected Plugin
Better Search – Relevant search results for WordPress
Affected Version
<= 2.5.2
CVSS
4.3Medium
Weakness type
CWE-352 · Cross-Site Request Forgery (CSRF)
CVE
CVE-2021-4400
View all Better Search – Relevant search results for WordPress vulnerabilities

At a glance

CVE-2021-4400 is a medium-severity Cross-Site Request Forgery (CSRF) vulnerability in the Better Search WordPress plugin, affecting versions <= 2.5.2. It carries a CVSS score of 4.3 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 2.5.3; sites on affected versions should update now. Disclosed March 2021, reported by Jerome Bruandet.

Vulnerability Overview

The Better Search plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 2.5.2. This is due to missing or incorrect nonce validation on the bsearch_process_settings_import() and bsearch_process_settings_export() functions. This makes it possible for unauthenticated attackers to import and export settings via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site.

CWE-352: Cross-Site Request Forgery (CSRF)

Better Search <= 2.5.2 carries this weakness at bsearch_process_settings_import(), and reaching it takes a caller who can reach the endpoint. Cross-site request forgery abuses the fact that browsers attach a victim's cookies to any request, so a state-changing action that only checks who you are, not whether you meant to act, can be triggered from another site.

An attacker who gets a logged-in user to load a crafted page can perform that action as them, with the impact scaling to whatever the victim's role is allowed to do. For Better Search the fix is 2.5.3: builds <= 2.5.2 are affected, anything from 2.5.3 onward is not.

Remediation

Update to version 2.5.3, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Better Search: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Better Search 2.5.3 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-4400https://www.wordfence.com/threat-intel/vulnerabilities/id/7acbcf74-2bae-412b-bf9d-70287a91deeahttps://nvd.nist.gov/vuln/detail/CVE-2021-4400

Related records

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