A WordPress anti-spam plugin with over 60,000 installations covered a PHP Object injection vulnerability that emerged from inappropriate sanitization of inputs, subsequently allowing base64 encoded user input.
Unauthenticated PHP Item Injection
A vulnerability was discovered in the popular Stop Spammers Security|Block Spam Users, Comments, 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 capability for users to input IP addresses to obstruct.
It is a needed practice for any WordPress plugin or type that accepts a user input to only allow particular inputs, like text, images, email addresses, whatever input is anticipated.
Unexpected inputs must be filtered out. That filtering procedure that stays out undesirable inputs is called sanitization.
For example, a contact form need to have a function that examines what is sent and block (sterilize) anything that is not text.
The vulnerability discovered in the anti-spam plugin allowed encoded input (base64 encoded) which can then trigger a type of vulnerability called a PHP Things injection vulnerability.
The description of the vulnerability published on the WPScan site explains the problem as:
“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are used as 2nd obstacle, which could cause PHP Object injection if a plugin installed on the blog has a suitable gizmo chain …”
The classification of the vulnerability is Insecure Deserialization.
The non-profit Open Web Application Security Task (OWASP) explains the prospective effect of these sort of vulnerabilities as major, which may or may not hold true particular to this vulnerability.
The description at OWASP:
“The impact of deserialization flaws can not be overstated. These defects can result in remote code execution attacks, among the most major attacks possible.The business effect depends upon the defense needs of the application and data. “But OWASP likewise keeps in mind that exploiting this sort of vulnerability tends to be difficult:”Exploitation of deserialization is somewhat hard,
as off the rack makes use of rarely work without changes or tweaks to the hidden make use of 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 numerous updates)keeps in mind the fix as an improvement for security. Users of the Stop Spam Security plugin need to think about upgrading to the latest
variation in order to avoid a hacker from making use of the plugin. Read the official alert at the United States Government National Vulnerability Database
: CVE-2022-4120 Information Read the WPScan publication of details connected to this vulnerability:
Stop Spammers Security