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 covered a PHP Item injection vulnerability that emerged from incorrect sanitization of inputs, subsequently 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, 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 just enable particular inputs, like text, images, email addresses, whatever input is expected.

Unexpected inputs ought to be filtered out. That filtering process that keeps out undesirable inputs is called sanitization.

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

The vulnerability discovered in the anti-spam plugin allowed encoded input (base64 encoded) which can then activate a kind of vulnerability called a PHP Item 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 used as 2nd difficulty, which could result in PHP Things injection if a plugin installed on the blog site has an appropriate device chain …”

The category of the vulnerability is Insecure Deserialization.

The non-profit Open Web Application Security Task (OWASP) describes the prospective impact of these kinds of vulnerabilities as serious, which might or might not hold true specific to this vulnerability.

The description at OWASP:

“The effect of deserialization defects can not be overstated. These defects can cause remote code execution attacks, among the most serious attacks possible.The company impact depends upon the defense requirements of the application and information. “But OWASP also notes that exploiting this sort of vulnerability tends to be tough:”Exploitation of deserialization is rather tough,

as off the shelf makes use of hardly ever work without modifications 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 enhancement for security. Users of the Stop Spam Security plugin must consider updating to the latest

version in order to prevent a hacker from making use of the plugin. Read the official notification at the United States Government National Vulnerability Database

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

Stop Spammers Security