CVE-2018-16561 Denial of service in SIMATIC S7-300 CPUs

What is CVE-2018-16561?

CVE-2018-16561 is a high-severity denial of service vulnerability in Siemens SIMATIC S7-300 CPUs, published on 17 Apr 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A vulnerability has been identified in SIMATIC S7-300 CPUs (All versions < V3.X.16). The affected CPUs improperly validate S7 communication packets which could cause a Denial-of-Service condition of the CPU. The CPU will remain in DEFECT mode until manual restart. Successful exploitation requires an attacker to be able to send a specially crafted S7 communication packet to a communication interface of the CPU. This includes Ethernet, PROFIBUS, and Multi Point Interfaces (MPI). No user interaction or privileges are required to exploit the security vulnerability. The vulnerability could allow causing a Denial-of-Service condition of the core functionality of the CPU, compromising the availability of the system. At the time of advisory publication no public exploitation of this security vulnerability was known. Siemens confirms the security vulnerability and provides mitigations to resolve the security issue.

Weakness: CWE-20

Which versions are affected by CVE-2018-16561?

It affects 4 products.

Products include Siemens Simatic S7-300 Firmware, Siemens Simatic S7-300f Firmware, Siemens Simatic S7-300fs Firmware, Siemens Simatic S7-300t Firmware.

How do I fix CVE-2018-16561?

No fix has been published for CVE-2018-16561 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2018-16561 being exploited?

There is no known exploitation of CVE-2018-16561 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-w9hm-m2x5-5x42.