A WordPress anti-spam plugin with over 60,000 setups covered a PHP Things injection vulnerability that developed from improper sanitization of inputs, subsequently enabling base64 encoded user input.
Unauthenticated PHP Item Injection
A vulnerability was discovered in the popular Stop Spammers Security|Block Spam Users, Remarks, Types WordPress plugin.
The function of the plugin is to stop spam in comments, 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 required practice for any WordPress plugin or form that accepts a user input to only allow particular inputs, like text, images, email addresses, whatever input is expected.
Unforeseen inputs ought to be strained. That filtering process that stays out undesirable inputs is called sanitization.
For example, a contact type ought to have a function that examines what is submitted and block (sanitize) anything that is not text.
The vulnerability discovered in the anti-spam plugin enabled encoded input (base64 encoded) which can then activate a type of vulnerability called a PHP Item injection vulnerability.
The description of the vulnerability published on the WPScan website describes the concern as:
“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are used as 2nd difficulty, which could result in PHP Object injection if a plugin set up on the blog site has an appropriate gadget chain …”
The category of the vulnerability is Insecure Deserialization.
The non-profit Open Web Application Security Task (OWASP) describes the potential impact of these sort of vulnerabilities as major, which might or may not hold true specific to this vulnerability.
The description at OWASP:
“The effect of deserialization flaws can not be overemphasized. These defects can lead to remote code execution attacks, among the most serious attacks possible.The service effect depends upon the defense requirements of the application and data. “However OWASP also notes that exploiting this sort of vulnerability tends to be challenging:”Exploitation of deserialization is somewhat hard,
as off the rack makes use of rarely work without modifications or tweaks to the underlying 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 fix as an enhancement for security. Users of the Stop Spam Security plugin ought to think about upgrading to the latest
version in order to prevent a hacker from making use of the plugin. Read the main alert at the United States Government National Vulnerability Database
: CVE-2022-4120 Detail Check out the WPScan publication of details associated with this vulnerability:
Stop Spammers Security