09 11 __link__ — Simatic S7 200 S7 300 Mmc Password Unlock 2006

The blog post you're likely thinking of refers to a seminal discovery in the Siemens SIMATIC S7 community regarding a vulnerability in how passwords were stored on Micro Memory Cards (MMC). On or around 11 September 2006

Because the XOR salt became known and static, the community reverse-engineered a lookup table. The unlock tool effectively re-applies that exact timestamp to the MMC, essentially rolling back the security to a state where the password algorithm is deterministic. simatic s7 200 s7 300 mmc password unlock 2006 09 11

The original integrator is long gone. The documentation is lost. The machine is down, and management is demanding a fix. The blog post you're likely thinking of refers

For S7-200

It is still possible to recover or wipe these. Tools exist (often running in DOSBox or XP Virtual Machines) that can interface via PPI cables to clear the password. However, keep in mind the S7-200 is end-of-life. S7-200: CPU 22x series with firmware < 1

For the Simatic S7-200 PLC, the MMC password can be reset using the following steps:

2. The S7-300 MMC Scenario (The Brick Wall)

This is where the confusion lay. Many users assumed the S7-300 MMC functioned like a USB stick or an S7-200 cartridge. It did not.

2.3 Which Devices are Affected?

  • S7-200: CPU 22x series with firmware < 1.20 (date code before 2007)
  • S7-300: CPU 31xC, 31x-2DP, and 31x-2PN/DP with MMC firmware from 2005-2006
  • Specific MMC formats: Non-Siemens branded MMCs (e.g., Sandisk 64MB, 128MB) often have weaker protection.

The "unlock" feature for the S7-300 focuses on reading the password directly from the MMC, as it is stored in a known location on the card's image.