PT-2013-87: Insuffient Entropy in Siemens SIMATIC S7-1200 CPU PLC

Vulnerable platform

Siemens SIMATIC S7-1200 CPU PLC
Version: 3.x and earlier


Severity level

Severity level: High
Impact: Session Hijaking, Information Disclosure, Denial of Service
Access Vector: Remote

CVSS v2:
Base Score: 8.3
Vector: (AV:N/AC:M/Au:N/C:P/I:P/A:C)

CVE: CVE-2014-2250

Platform description

SIMATIC S7-1200 controllers are new modular miniature controllers. Due to the compact modular design with a high performance at the same time, the SIMATIC S7-1200 is suitable for a wide variety of automation applications. Its range of use extends from the replacement of relays and contactors up to complex automation tasks in networks and within distributed structures.

Vulnerability description

The specialists of the Positive Research center have detected an Insuffient Entropy vulnerability in Siemens SIMATIC S7-1200 CPU PLC.

Due to low entropy in its random number generator, the integrated web server’s authentication method (port 80/tcp and port 443/tcp) could allow attackers to hijack web sessions over the network if the session token can be predicted.

How to fix

Update your firmware up to the latest version

Advisory status

05.08.2013 - Vendor gets vulnerability details
20.03.2014 - Vendor releases fixed version and details
25.03.2014 - Public disclosure


The vulnerability was detected by Alexey Osipov and Alexander Timorin, Positive Research Center (Positive Technologies Company)


Reports on the vulnerabilities previously discovered by Positive Research: