A WordPress anti-spam plugin with over 60,000 installations covered 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, Comments, Forms WordPress plugin.
The function 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 block.
It is a needed practice for any WordPress plugin or kind that accepts a user input to only allow specific inputs, like text, images, e-mail addresses, whatever input is anticipated.
Unforeseen inputs should be strained. That filtering process that keeps 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 allowed encoded input (base64 encoded) which can then activate a kind of vulnerability called a PHP Things injection vulnerability.
The description of the vulnerability released on the WPScan website describes the issue as:
“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are utilized as second obstacle, which could result in PHP Object injection if a plugin set up on the blog site has an appropriate gizmo chain …”
The category of the vulnerability is Insecure Deserialization.
The non-profit Open Web Application Security Job (OWASP) explains the potential impact of these sort of vulnerabilities as major, which might or may not be the case specific to this vulnerability.
The description at OWASP:
“The effect of deserialization flaws can not be overstated. These defects can lead to remote code execution attacks, one of the most serious attacks possible.The organization impact depends on the defense requirements of the application and data. “However OWASP likewise keeps in mind that exploiting this sort of vulnerability tends to be difficult:”Exploitation of deserialization is somewhat difficult,
as off the rack exploits hardly ever work without changes or tweaks to the underlying exploit code.”The vulnerability in the Stop Spammers Security WordPress
plugin was repaired in variation 2022.6 The main Stop Spammers Security changelog (a description with dates of different updates)keeps in mind the fix as an improvement for security. Users of the Stop Spam Security plugin need to consider upgrading to the latest
variation in order to prevent a hacker from exploiting the plugin. Read the official alert at the United States Federal Government National Vulnerability Database
: CVE-2022-4120 Information Read the WPScan publication of information connected to this vulnerability:
Stop Spammers Security