Some third-party tools and services claim to offer password recovery or unlocking features for S7-300 PLCs:
"Investigating Current PLC Security Issues Regarding Siemens S7 Communications and TIA Portal" (Hui & McLaughlin, 2018): Documents how man-in-the-middle (MITM) replay attacks unlock s7-300 plc password
However, this longevity often leads to a common headache: Some third-party tools and services claim to offer