CVE-2020-27738 : Security Advisory and Response

A vulnerability has been identified in various Siemens products, allowing for a denial-of-service attack due to improper validation of pointer offset values.

Understanding CVE-2020-27738

This CVE affects multiple Siemens products due to a vulnerability in DNS domain name record decompression functionality.

What is CVE-2020-27738?

The parsing of malformed responses could lead to a read access past the end of an allocated structure, enabling a denial-of-service condition by an attacker with network privileges.

The Impact of CVE-2020-27738

The vulnerability could result in a denial-of-service attack on affected Siemens products, potentially disrupting critical operations.

Technical Details of CVE-2020-27738

This section provides detailed technical information about the CVE.

Vulnerability Description

The DNS domain name record decompression functionality in Siemens products fails to properly validate pointer offset values, allowing for a read access beyond allocated memory.

Affected Systems and Versions

APOGEE PXC Compact (BACnet) (All versions < V3.5.5)
APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20)
APOGEE PXC Modular (BACnet) (All versions < V3.5.5)
APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20)
Nucleus NET (All versions)
Nucleus ReadyStart V3 (All versions < V2017.02.3)
Nucleus ReadyStart V4 (All versions < V4.1.0)
Nucleus Source Code (Versions including affected DNS modules)
SIMOTICS CONNECT 400 (All versions < V0.5.0.0)
TALON TC Compact (BACnet) (All versions < V3.5.5)
TALON TC Modular (BACnet) (All versions < V3.5.5)

Exploitation Mechanism

The vulnerability can be exploited by an attacker with network privileges to send malformed responses, triggering a denial-of-service condition.

Mitigation and Prevention

Protecting systems from CVE-2020-27738 is crucial to prevent potential disruptions.

Immediate Steps to Take

Apply patches provided by Siemens to address the vulnerability.
Monitor network traffic for any signs of exploitation.
Restrict network access to critical systems.

Long-Term Security Practices

Regularly update and patch all Siemens products to mitigate known vulnerabilities.
Conduct security assessments and audits to identify and address potential weaknesses.

Patching and Updates

Siemens has released patches to address the vulnerability. Ensure all affected systems are updated to the latest secure versions.