Description
A predictable value range from previous values issue was discovered in Schneider Electric Modicon PLCs Modicon M221, firmware versions prior to Version 1.5.0.0, Modicon M241, firmware versions prior to Version 4.0.5.11, and Modicon M251, firmware versions prior to Version 4.0.5.11. The affected products generate insufficiently random TCP initial sequence numbers that may allow an attacker to predict the numbers from previous values. This may allow an attacker to spoof or disrupt TCP connections.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Schneider Electric | Modicon M221 | < 1.5.0.0 | 1.5.0.0 |
| Schneider Electric | Modicon M241 | < 4.0.5.11 | 4.0.5.11 |
| Schneider Electric | Modicon M251 | < 4.0.5.11 | 4.0.5.11 |
Advisories 1
- ICSA-17-089-02 Schneider Electric Modicon PLCs CISA ICS & IT advisories · Mar 30, 2017