Senior LevelPHP 8+
How do PHP Object Injection (unserialize) vulnerabilities lead to Remote Code Execution via POP chains?
❓ Interview Prompt: Explain PHP Object Injection vulnerabilities, magic method triggers (__destruct, __toString), Property Oriented Programming (POP) chains, and RCE.
If an application passes untrusted user input directly to 'unserialize($_COOKIE["data"])', it exposes a critical PHP Object Injection / Remote Code Execution (RCE) vulnerability.
How POP Chains Execute RCE:
1
Object Injection: Attacker sends a crafted serialized payload representing an object from a vendor package present in 'vendor/'.
2
Magic Method Trigger: When 'unserialize()' runs, PHP automatically triggers magic methods ('__wakeup()', '__destruct()', '__toString()').
3
Property Oriented Programming (POP) Gadgets: The magic method calls another method on an injected property object, chaining internal method invocations across application classes until reaching a "sink" function ('system($cmd)', 'exec()', 'eval()')!
Code Implementation Example
php
<?php
// Example of a POP Gadget Vulnerability Chain
class TempFileCleaner {
public string $filename;
public function __destruct() {
// SINK: Executes system command when object is garbage collected!
unlink($this->filename);
}
}
// ❌ VULNERABLE: Unserializing user-controlled cookie payload!
// unserialize($_COOKIE['session']);💡Conceptual POP Gadget vulnerability where unserialize triggers destructive __destruct magic methods.
🎯 Interview Key Takeaway
PHP Object Injection triggers magic methods (__destruct) on unserialized objects, chaining POP gadgets to execute Remote Code Execution.
#Security#unserialize#Object Injection#POP Chain#Senior
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