A WordPress anti-spam plugin with over 60,000 installations patched a PHP Things injection vulnerability that occurred from inappropriate sanitization of inputs, consequently permitting base64 encoded user input.
Unauthenticated PHP Item Injection
A vulnerability was discovered in the popular Stop Spammers Security|Block Spam Users, Comments, Types WordPress plugin.
The function of the plugin is to stop spam in remarks, types, 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 only permit specific inputs, like text, images, email addresses, whatever input is anticipated.
Unforeseen inputs should be removed. That filtering process that keeps out undesirable inputs is called sanitization.
For example, a contact form need to have a function that checks what is sent and block (sanitize) 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 Things injection vulnerability.
The description of the vulnerability released on the WPScan site describes the concern as:
“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are used as second obstacle, which could lead to PHP Item injection if a plugin set up on the blog has a suitable device chain …”
The classification of the vulnerability is Insecure Deserialization.
The non-profit Open Web Application Security Task (OWASP) describes the possible effect of these sort of vulnerabilities as severe, which may or may not be the case specific to this vulnerability.
The description at OWASP:
“The impact of deserialization defects can not be overemphasized. These flaws can lead to remote code execution attacks, one of the most serious attacks possible.The service effect depends upon the security needs of the application and data. “However OWASP also keeps in mind that exploiting this kind of vulnerability tends to be hard:”Exploitation of deserialization is somewhat difficult,
as off the shelf makes use of hardly ever work without changes or tweaks to the underlying exploit code.”The vulnerability in the Stop Spammers Security WordPress
plugin was fixed in version 2022.6 The official Stop Spammers Security changelog (a description with dates of various updates)keeps in mind the repair as an improvement for security. Users of the Stop Spam Security plugin should consider updating to the latest
variation in order to prevent a hacker from exploiting the plugin. Check out the official notification at the United States Federal Government National Vulnerability Database
: CVE-2022-4120 Detail Check out the WPScan publication of information related to this vulnerability:
Stop Spammers Security