A WordPress anti-spam plugin with over 60,000 installations covered a PHP Things injection vulnerability that emerged from improper 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 function of the plugin is to stop spam in remarks, types, 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 form that accepts a user input to just enable specific inputs, like text, images, email addresses, whatever input is anticipated.
Unforeseen inputs should be filtered out. That filtering process that keeps out undesirable inputs is called sanitization.
For instance, a contact type should have a function that examines what is sent and block (sterilize) anything that is not text.
The vulnerability discovered in the anti-spam plugin permitted encoded input (base64 encoded) which can then set off a type of vulnerability called a PHP Object injection vulnerability.
The description of the vulnerability published on the WPScan site explains the issue as:
“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are utilized as 2nd challenge, which might lead to PHP Item injection if a plugin set up on the blog has a suitable gizmo chain …”
The classification of the vulnerability is Insecure Deserialization.
The non-profit Open Web Application Security Project (OWASP) describes the prospective impact of these kinds of vulnerabilities as severe, which might or might not be the case particular to this vulnerability.
The description at OWASP:
“The effect of deserialization defects can not be overstated. These defects can lead to remote code execution attacks, one of the most serious attacks possible.The business impact depends on the protection requirements of the application and information. “However OWASP also notes that exploiting this type of vulnerability tends to be difficult:”Exploitation of deserialization is rather tough,
as off the rack exploits rarely work without changes 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 numerous updates)keeps in mind the repair as an improvement for security. Users of the Stop Spam Security plugin should consider upgrading to the current
variation in order to avoid a hacker from making use of the plugin. Read the main alert at the United States Government National Vulnerability Database
: CVE-2022-4120 Detail Read the WPScan publication of details associated with this vulnerability:
Stop Spammers Security