WordPress Anti-Spam Plugin Vulnerability Impacts As Much As 60,000+ Websites

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

Unauthenticated PHP Object Injection

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

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

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

Unexpected inputs must be removed. That filtering process that stays out undesirable inputs is called sanitization.

For instance, a contact type should have a function that inspects what is sent and block (sanitize) anything that is not text.

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

The description of the vulnerability released on the WPScan website describes the problem as:

“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are used as 2nd obstacle, which might cause PHP Things injection if a plugin set up on the blog site has an appropriate gizmo chain …”

The classification of the vulnerability is Insecure Deserialization.

The non-profit Open Web Application Security Job (OWASP) explains the possible impact of these kinds of vulnerabilities as major, which may or may not hold true specific to this vulnerability.

The description at OWASP:

“The effect of deserialization flaws can not be overstated. These flaws can lead to remote code execution attacks, among the most severe attacks possible.The service effect depends on the security needs of the application and data. “But OWASP likewise notes that exploiting this sort of vulnerability tends to be tough:”Exploitation of deserialization is somewhat difficult,

as off the rack makes use of 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 fix as an improvement for security. Users of the Stop Spam Security plugin must consider updating to the latest

variation in order to avoid a hacker from making use of the plugin. Read the main notification at the United States Government National Vulnerability Database

: CVE-2022-4120 Detail Check out the WPScan publication of information related to this vulnerability:

Stop Spammers Security