NinjaFirewall <= 4.3.3 - Authenticated PHAR Deserialization
Strategic Overview
- Status
- Patched in 4.3.4
- Affected Version
< 4.3.4- CVSS
- 6.6Medium
- Weakness type
- CWE-502 · Deserialization of Untrusted Data
- CVE
CVE-2021-4451
At a glance
CVE-2021-4451 is a medium-severity Deserialization of Untrusted Data vulnerability in the NinjaFirewall (WP Edition) WordPress plugin, affecting versions < 4.3.4. It carries a CVSS score of 6.6 (reachable over the network; high confidentiality, integrity, availability impact). Exploitation requires an authenticated account. The issue is fixed in version 4.3.4; sites on affected versions should update now. Disclosed May 2021, reported by Chloe Chamberland.
Vulnerability Overview
The NinjaFirewall plugin for WordPress is vulnerable to Authenticated PHAR Deserialization in versions up to, and including, 4.3.3. This allows authenticated attackers to perform phar deserialization on the server. This deserialization can allow other plugin or theme exploits if vulnerable software is present (WordPress, and NinjaFirewall).
Technical Analysis
The vector marks this flaw as remotely reachable over the network, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.
CWE-502: Deserialization of Untrusted Data
Reaching this weakness in NinjaFirewall (WP Edition) < 4.3.4 takes any authenticated account. Deserialization of untrusted data means the application reconstructs objects from input a caller controls, letting the attacker choose which classes get instantiated and what their properties hold.
A workable chain turns deserialization into file writes, deletions or code execution, depending on what the loaded classes do in their magic methods. For NinjaFirewall (WP Edition) the fix is 4.3.4: builds < 4.3.4 are affected, anything from 4.3.4 onward is not.
Remediation
Update to version 4.3.4, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to NinjaFirewall (WP Edition): WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: NinjaFirewall (WP Edition) 4.3.4 closes this, and updating the plugin is the step that ends it.
- Firewall
- Scanner
- Alerts
External References
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