A WordPress anti-spam plugin with over 60,000 installations covered a PHP Item injection vulnerability that arose from incorrect sanitization of inputs, consequently allowing base64 encoded user input.
Unauthenticated PHP Item Injection
A vulnerability was found in the popular Stop Spammers Security|Block Spam Users, Comments, Types WordPress plugin.
The function 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 obstruct.
It is a required practice for any WordPress plugin or type that accepts a user input to just enable specific inputs, like text, images, email addresses, whatever input is expected.
Unexpected inputs need to be removed. That filtering procedure that stays out unwanted inputs is called sanitization.
For instance, a contact form should have a function that examines what is submitted 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 kind of vulnerability called a PHP Item injection vulnerability.
The description of the vulnerability published on the WPScan website describes the problem as:
“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are utilized as second obstacle, which could lead to PHP Things injection if a plugin set up on the blog site has an appropriate device chain …”
The classification of the vulnerability is Insecure Deserialization.
The non-profit Open Web Application Security Project (OWASP) explains the potential impact of these type of vulnerabilities as severe, which might or may not be the case particular to this vulnerability.
The description at OWASP:
“The impact of deserialization defects can not be overstated. These flaws can lead to remote code execution attacks, one of the most serious attacks possible.The organization effect depends upon the defense requirements of the application and information. “However OWASP also keeps in mind that exploiting this type of vulnerability tends to be challenging:”Exploitation of deserialization is somewhat challenging,
as off the rack makes use of rarely work without changes or tweaks to the hidden 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 different updates)notes the repair as an enhancement for security. Users of the Stop Spam Security plugin must think about updating to the current
variation in order to prevent a hacker from making use of the plugin. Check out the official notice 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