CVE-2021-4425

Defender Security <= 2.4.6 - Cross-Site Request Forgery Bypass

2021-03-01 00:00

Strategic Overview

Status: Patched in 2.4.6.1
Affected Plugin: Defender Security – Malware Scanner, Login Security & Firewall
Affected Version: <= 2.4.6
CVSS: 4.3Medium
Weakness type: CWE-352 · Cross-Site Request Forgery (CSRF)
CVE: CVE-2021-4425

View all Defender Security – Malware Scanner, Login Security & Firewall vulnerabilities

At a glance

CVE-2021-4425 is a medium-severity Cross-Site Request Forgery (CSRF) vulnerability in the Defender Security WordPress plugin, affecting versions <= 2.4.6. 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 2.4.6.1; sites on affected versions should update now. Disclosed March 2021, reported by Jerome Bruandet.

Vulnerability Overview

The Defender Security plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 2.4.6. This is due to missing or incorrect nonce validation on the verify_otp_login_time() function. This makes it possible for unauthenticated attackers to verify a one time login 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)

Defender Security <= 2.4.6 carries this weakness at verify_otp_login_time(), 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 Defender Security the fix is 2.4.6.1: builds <= 2.4.6 are affected, anything from 2.4.6.1 onward is not.

Remediation

Update to version 2.4.6.1, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Defender Security: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Defender Security 2.4.6.1 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-4425 https://www.wordfence.com/threat-intel/vulnerabilities/id/e772fbbe-33d5-46fa-a041-ab07d3f9318f https://nvd.nist.gov/vuln/detail/CVE-2021-4425

Related records

Other vulnerabilities in Defender Security – Malware Scanner, Login Security & Firewall

CVSS Vector

4.3

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeUnchanged
ConfidentialityNone
IntegrityLow
AvailabilityNone

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