A WordPress anti-spam plugin with over 60,000 installations covered a PHP Object injection vulnerability that arose from inappropriate 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 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 needed practice for any WordPress plugin or type that accepts a user input to only enable specific inputs, like text, images, e-mail addresses, whatever input is anticipated.
Unforeseen inputs need to be removed. That filtering procedure that stays out unwanted inputs is called sanitization.
For example, a contact kind ought to have a function that inspects what is submitted and block (sanitize) anything that is not text.
The vulnerability discovered in the anti-spam plugin permitted encoded input (base64 encoded) which can then activate a kind of vulnerability called a PHP Things injection vulnerability.
The description of the vulnerability published on the WPScan site explains the concern as:
“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are utilized as second obstacle, which might cause PHP Things injection if a plugin set up on the blog site has a suitable gadget chain …”
The classification of the vulnerability is Insecure Deserialization.
The non-profit Open Web Application Security Project (OWASP) describes the potential impact of these kinds of vulnerabilities as major, which may or may not be the case specific to this vulnerability.
The description at OWASP:
“The effect of deserialization flaws can not be overemphasized. These defects can cause remote code execution attacks, one of the most severe attacks possible.The organization impact depends on the defense needs of the application and information. “However OWASP also notes that exploiting this kind of vulnerability tends to be difficult:”Exploitation of deserialization is somewhat difficult,
as off the rack makes use of rarely work without modifications or tweaks to the underlying make use of 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 different updates)keeps in mind the repair as an improvement for security. Users of the Stop Spam Security plugin must think about updating to the latest
variation in order to avoid a hacker from making use of the plugin. Check out the main notification at the United States Federal Government National Vulnerability Database
: CVE-2022-4120 Detail Read the WPScan publication of details related to this vulnerability:
Stop Spammers Security