The S7-300 family (e.g., CPU 312, 314, 315-2DP) uses an MMC (Multimedia Card) as its external load memory. The MMC contains:
The password on an S7-300 MMC is not a simple PIN. It’s tied to the CPU’s serial number and a proprietary Siemens hashing algorithm. However, early firmware versions (before 2007) had a significant flaw. simatic s7 200 s7 300 mmc password unlock 2006 09 11
The vulnerability works as follows:
This is similar to the infamous "S7-1200 2009" protection bypass but targets the older MMC-based systems. The S7-300 family (e
Once you regain access: