Security Experts:

Siemens SIMATIC Controllers Vulnerable to DoS Attacks

Siemens has released a firmware update for its SIMATIC S7-1500 programmable logic controller (PLC) to address two vulnerabilities, including a high severity issue that can be exploited for denial-of-service (DoS) attacks.

According to advisories published this week by Siemens and ICS-CERT, the flawed SIMATIC S7-1500 CPU family is used worldwide in industrial environments in the critical manufacturing, chemical, and food and beverages sectors.Siemens SIMATIC controllers

The more serious of the vulnerabilities, with a CVSS v3 score of 7.5, is CVE-2016-2200. The flaw allows an attacker to trigger a DoS condition on affected devices by sending specially crafted packets to port 102/TCP. This causes the device to restart and remain in STOP mode until it’s manually put into RUN mode.

The second issue, which has “low” severity, can be exploited under certain conditions to decrease the efficiency of a feature designed to provide protection against replay attacks (CVE-2016-2201).

The security holes can only be exploited by an attacker who has network access to the vulnerable devices, Siemens said.

The vendor advises customers to operate SIMATIC S7-1500 controllers only on trusted networks, as described in the company’s operational guidelines for industrial security, and update the firmware to version 1.8.3, which patches the vulnerabilities. All prior versions of the firmware are affected.

The flaws were reported to Siemens by France-based security firms Lexfo and Amossys via the country’s National Agency for Computer Security (ANSSI).

This is the second security update released by Siemens in 2016. In January, the German industrial conglomerate made available firmware updates to address a cross-site scripting (XSS) vulnerability affecting some of its building automation products.

Related: Recently Patched NTP Flaws Affect Siemens RUGGEDCOM Devices

Related: Learn More at the ICS Cyber Security Conference

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.