WordPress Anti-Spam Plugin Vulnerability Impacts Up To 60,000+ Websites

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A WordPress anti-spam plugin with over 60,000 setups patched a PHP Item injection vulnerability that occurred from improper sanitization of inputs, consequently permitting base64 encoded user input.

Unauthenticated PHP Object Injection

A vulnerability was found in the popular Stop Spammers Security|Block Spam Users, Remarks, Forms WordPress plugin.

The purpose of the plugin is to stop spam in remarks, forms, and sign-up registrations. It can stop spam bots and has the ability for users to input IP addresses to obstruct.

It is a required practice for any WordPress plugin or form that accepts a user input to only permit particular inputs, like text, images, e-mail addresses, whatever input is expected.

Unanticipated inputs ought to be filtered out. That filtering procedure that keeps out undesirable inputs is called sanitization.

For instance, a contact form must have a function that inspects what is sent and block (sterilize) anything that is not text.

The vulnerability found in the anti-spam plugin allowed encoded input (base64 encoded) which can then trigger a type of vulnerability called a PHP Item injection vulnerability.

The description of the vulnerability released on the WPScan website explains the issue as:

“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are utilized as second challenge, which could lead to PHP Item injection if a plugin installed on the blog has an ideal gadget chain …”

The category of the vulnerability is Insecure Deserialization.

The non-profit Open Web Application Security Task (OWASP) explains the potential effect of these type of vulnerabilities as major, which might or may not be the case specific to this vulnerability.

The description at OWASP:

“The impact of deserialization flaws can not be overemphasized. These defects can lead to remote code execution attacks, among the most major attacks possible.The service impact depends on the protection requirements of the application and data. “However OWASP also keeps in mind that exploiting this kind of vulnerability tends to be difficult:”Exploitation of deserialization is rather hard,

as off the shelf exploits hardly ever work without modifications or tweaks to the hidden make use of code.”The vulnerability in the Stop Spammers Security WordPress

plugin was repaired in version 2022.6 The main Stop Spammers Security changelog (a description with dates of various updates)keeps in mind the repair as an improvement for security. Users of the Stop Spam Security plugin must think about upgrading to the most recent

variation in order to avoid a hacker from exploiting the plugin. Read the main alert at the United States Federal Government National Vulnerability Database

: CVE-2022-4120 Information Read the WPScan publication of details related to this vulnerability:

Stop Spammers Security