A WordPress anti-spam plugin with over 60,000 setups covered a PHP Things injection vulnerability that occurred from incorrect sanitization of inputs, consequently allowing base64 encoded user input.
Unauthenticated PHP Things 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, forms, and sign-up registrations. It can stop spam bots and has the capability for users to input IP addresses to block.
It is a needed practice for any WordPress plugin or type that accepts a user input to only allow particular inputs, like text, images, e-mail addresses, whatever input is expected.
Unforeseen inputs ought to be filtered out. That filtering procedure that stays 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 permitted encoded input (base64 encoded) which can then trigger a type of vulnerability called a PHP Object injection vulnerability.
The description of the vulnerability released on the WPScan website describes the problem as:
“The plugin passes base64 encoded user input to the unserialize() PHP function when CAPTCHA are used as second obstacle, which could cause PHP Things injection if a plugin installed on the blog has a suitable device chain …”
The classification of the vulnerability is Insecure Deserialization.
The non-profit Open Web Application Security Job (OWASP) explains the possible impact of these sort of vulnerabilities as serious, which may or might not be the case particular to this vulnerability.
The description at OWASP:
“The effect of deserialization defects can not be overemphasized. These flaws can cause remote code execution attacks, among the most major attacks possible.The business effect depends upon the protection requirements of the application and data. “But OWASP also notes that exploiting this sort of vulnerability tends to be hard:”Exploitation of deserialization is somewhat difficult,
as off the rack exploits hardly ever work without changes or tweaks to the hidden make use of code.”The vulnerability in the Stop Spammers Security WordPress
plugin was repaired in variation 2022.6 The official Stop Spammers Security changelog (a description with dates of different updates)notes the repair as an improvement for security. Users of the Stop Spam Security plugin must think about upgrading to the current
version in order to avoid a hacker from making use of the plugin. Read the official notice at the United States Government National Vulnerability Database
: CVE-2022-4120 Information Check out the WPScan publication of details connected to this vulnerability:
Stop Spammers Security