WordPress Anti-Spam Plugin Vulnerability Affects Approximately 60,000+ Sites

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A WordPress anti-spam plugin with over 60,000 installations covered a PHP Item injection vulnerability that emerged from incorrect 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 purpose of the plugin is to stop spam in remarks, kinds, and sign-up registrations. It can stop spam bots and has the capability for users to input IP addresses to block.

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

Unforeseen inputs must be removed. That filtering procedure that stays out undesirable inputs is called sanitization.

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

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

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

“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are used as second obstacle, which might result in PHP Item injection if a plugin set up on the blog has a suitable gadget chain …”

The classification of the vulnerability is Insecure Deserialization.

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

The description at OWASP:

“The impact of deserialization defects can not be overstated. These flaws can lead to remote code execution attacks, among the most serious attacks possible.The business impact depends on the defense needs of the application and data. “However OWASP also notes that exploiting this kind of vulnerability tends to be difficult:”Exploitation of deserialization is somewhat tough,

as off the shelf makes use of hardly ever work without modifications or tweaks to the underlying 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)notes the fix as an enhancement for security. Users of the Stop Spam Security plugin ought to consider updating to the most recent

version in order to prevent a hacker from exploiting the plugin. Check out the main notice at the United States Government National Vulnerability Database

: CVE-2022-4120 Detail Read the WPScan publication of information connected to this vulnerability:

Stop Spammers Security