Better Search Replace <= 1.4.4 - Unauthenticated PHP Object Injection
Strategic Overview
- Status
- Patched in 1.4.5
- Affected Plugin
- Better Search Replace
- Affected Version
<= 1.4.4- CVSS
- 8.8High
- Weakness type
- CWE-502 · Deserialization of Untrusted Data
- CVE
CVE-2023-6933
At a glance
CVE-2023-6933 is a high-severity Deserialization of Untrusted Data vulnerability in the Better Search Replace WordPress plugin, affecting versions <= 1.4.4. It carries a CVSS score of 8.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 1.4.5; sites on affected versions should update now. Disclosed January 2024, reported by Sam Pizzey (mopman).
Vulnerability Overview
The Better Search Replace plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 1.4.4 via deserialization of untrusted input. This makes it possible for unauthenticated attackers to inject a PHP Object. No POP chain is present in the vulnerable plugin. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.
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. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.
CWE-502: Deserialization of Untrusted Data
Reaching this weakness in Better Search Replace <= 1.4.4 takes no account at all. 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 Better Search Replace the fix is 1.4.5: builds <= 1.4.4 are affected, anything from 1.4.5 onward is not.
Remediation
Update to version 1.4.5, or a newer patched version
How does WordSec protect against this?
Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: 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: Better Search Replace 1.4.5 closes this, and updating the plugin is the step that ends it.
- Firewall
- Scanner
- Login Security
External References
Related records
Other vulnerabilities in Better Search Replace
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