Engine V3.4.0 Exploit - Zend

class Vuln 
    function __destruct() 
        // Override get_properties pointer via memory spray
$obj = new Vuln();
// Trigger via unserialize() with crafted property handler offset

One of the most famous exploits targeting the ZE v3.4.0 era was the "PHP phar:// deserialization" vulnerability. While the bug existed in the phar extension, the root cause lived in the Zend Engine's object instantiation handlers.

The Mechanism: When PHP unserializes data, the Zend Engine calls zend_object_std_init. In v3.4.0, a race condition existed between the destruction of a class's __destruct method and the restoration of the object's properties. zend engine v3.4.0 exploit

Exploit Workflow:

Consequences: An attacker could overwrite the zend_object handlers table, redirecting function calls (like get_class) to system(), achieving RCE with the server's privileges. One of the most famous exploits targeting the ZE v3

| Component | Vulnerability Type | Example | |-----------|--------------------|---------| | zend_gc (garbage collector) | Use-after-free | Recursive array destruction | | zend_hash (HashTable) | Double free / out-of-bounds read | Crafted array keys | | zend_objects (object handlers) | Type confusion | Overriding get_properties | | zend_vm (opcode handlers) | JIT miscompilation (not in 3.4.0) | N/A (no JIT yet) | | zend_string | Off-by-one | zend_string_realloc | zend engine v3.4.0 exploit