CVE-2021-27385 : What You Need to Know

A vulnerability has been identified in various Siemens products including SIMATIC HMI Panels and SINAMICS drives. An attacker could exploit this flaw to trigger a Denial-of-Service condition by sending specially crafted packets to the SmartVNC device layout handler on the client side.

Understanding CVE-2021-27385

This CVE impacts Siemens SIMATIC HMI Panels and SINAMICS drives, potentially leading to a Denial-of-Service vulnerability.

What is CVE-2021-27385?

The CVE-2021-27385 vulnerability affects multiple Siemens products, allowing a remote attacker to send malicious packets to SmartVNC device layout handler, leading to a Denial-of-Service condition due to uncontrolled resource consumption.

The Impact of CVE-2021-27385

The vulnerability could be exploited by an attacker to consume excessive resources, resulting in a system crash or unresponsive state, impacting the availability of the affected devices.

Technical Details of CVE-2021-27385

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The vulnerability allows a remote attacker to influence resource consumption by sending specially crafted packets to the affected devices' SmartVNC device layout handler, leading to a Denial-of-Service condition.

Affected Systems and Versions

Siemens products affected include SIMATIC HMI Comfort Panels, SIMATIC HMI KTP Mobile Panels, SIMATIC WinCC Runtime Advanced, SINAMICS GH150, GL150, GM150, SH150, SL150, SM120, SM150, and SM150i.

Exploitation Mechanism

By sending specially crafted packets to the SmartVNC device layout handler on the client side, an attacker can trigger a resource consumption issue, causing a Denial-of-Service condition.

Mitigation and Prevention

To mitigate the CVE-2021-27385 vulnerability, immediate and long-term security measures should be implemented.

Immediate Steps to Take

Apply security patches provided by Siemens for the affected products to address the vulnerability.
Implement network segmentation and access controls to minimize exposure to potential attackers.

Long-Term Security Practices

Regularly update and patch all Siemens products to protect against known vulnerabilities.
Conduct security assessments and audits to proactively identify and address potential security gaps.

Patching and Updates

Ensure that all affected products are updated to the recommended versions (V15.1 Update 6 for some and V16 Update 4 for others) to mitigate the CVE-2021-27385 vulnerability.