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

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A WordPress anti-spam plugin with over 60,000 installations patched a PHP Things injection vulnerability that emerged from improper sanitization of inputs, subsequently permitting base64 encoded user input.

Unauthenticated PHP Item Injection

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

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

It is a needed practice for any WordPress plugin or type that accepts a user input to only allow particular inputs, like text, images, e-mail addresses, whatever input is anticipated.

Unexpected inputs must be strained. That filtering process that keeps out unwanted inputs is called sanitization.

For example, a contact kind need to have a function that checks what is submitted and block (sterilize) anything that is not text.

The vulnerability discovered in the anti-spam plugin permitted encoded input (base64 encoded) which can then activate a type of vulnerability called a PHP Things injection vulnerability.

The description of the vulnerability published on the WPScan site 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 result in PHP Item injection if a plugin set up on the blog has an appropriate device chain …”

The category of the vulnerability is Insecure Deserialization.

The non-profit Open Web Application Security Job (OWASP) describes the possible impact of these type of vulnerabilities as severe, which might or may not be the case specific to this vulnerability.

The description at OWASP:

“The impact of deserialization defects can not be overstated. These defects can lead to remote code execution attacks, one of the most major attacks possible.The service impact depends upon the security needs of the application and information. “But OWASP also notes that exploiting this type of vulnerability tends to be tough:”Exploitation of deserialization is somewhat difficult,

as off the shelf makes use of rarely work without changes or tweaks to the underlying exploit 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 numerous updates)notes the fix as an improvement for security. Users of the Stop Spam Security plugin need to consider updating to the current

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

: CVE-2022-4120 Information Read the WPScan publication of details associated with this vulnerability:

Stop Spammers Security