A WordPress anti-spam plugin with over 60,000 setups patched a PHP Things injection vulnerability that emerged from incorrect sanitization of inputs, consequently enabling base64 encoded user input.
Unauthenticated PHP Things 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, 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 required practice for any WordPress plugin or type that accepts a user input to just permit particular inputs, like text, images, e-mail addresses, whatever input is expected.
Unexpected inputs must be removed. That filtering procedure that stays out undesirable inputs is called sanitization.
For instance, a contact form should have a function that inspects what is sent and block (sterilize) anything that is not text.
The vulnerability found in the anti-spam plugin permitted encoded input (base64 encoded) which can then set off a type of vulnerability called a PHP Item injection vulnerability.
The description of the vulnerability released on the WPScan site explains the problem as:
“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are utilized as 2nd obstacle, which might result in PHP Things injection if a plugin set up on the blog has an ideal gadget chain …”
The classification of the vulnerability is Insecure Deserialization.
The non-profit Open Web Application Security Job (OWASP) describes the prospective effect of these sort of vulnerabilities as severe, which might or may 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 major attacks possible.The organization effect depends upon the security 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 difficult,
as off the rack exploits hardly ever work without modifications or tweaks to the underlying exploit code.”The vulnerability in the Stop Spammers Security WordPress
plugin was fixed in variation 2022.6 The main Stop Spammers Security changelog (a description with dates of various updates)keeps in mind the repair as an enhancement for security. Users of the Stop Spam Security plugin should consider upgrading to the latest
version in order to prevent a hacker from exploiting the plugin. Check out the main notification at the United States Government National Vulnerability Database
: CVE-2022-4120 Information Read the WPScan publication of information related to this vulnerability:
Stop Spammers Security