SSA-669158

Siemens Security Advisory by Siemens ProductCERT

SSA-669158: DNS Client Vulnerabilities in SIMOTICS CONNECT 400

Publication Date:	2021-04-13
Last Update:	2022-03-08
Current Version:	V1.1
CVSS v3.1 Base Score:	6.5

SUMMARY

SIMOTICS CONNECT 400 is affected by DNS Client vulnerabilities as initially reported in Siemens Security Advisory SSA-705111 (https://cert-portal.siemens.com/productcert/pdf/ssa-705111.pdf) for the DNS Module in Nucleus RTOS.

Siemens has released updates for the SIMOTICS CONNECT 400 and recommends to update to the latest version.

AFFECTED PRODUCTS AND SOLUTION

Affected Product and Versions	Remediation
SIMOTICS CONNECT 400: All versions < V0.5.0.0	Update to V0.5.0.0 or later version https://support.industry.siemens.com/cs/ww/en/view/109778383/
SIMOTICS CONNECT 400: All versions >= V0.5.0.0 < V1.0.0.0 only affected by CVE-2021-25677	Update to V1.0.0.0 or later version https://support.industry.siemens.com/cs/ww/en/view/109778383/

WORKAROUNDS AND MITIGATIONS

Siemens has not identified any additional specific workarounds or mitigations. Please follow the General Security Recommendations.

Product specific mitigations can be found in the section Affected Products and Solution.

GENERAL SECURITY RECOMMENDATIONS

As a general security measure, Siemens strongly recommends to protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends to configure the environment according to Siemens’ operational guidelines for Industrial Security (Download: https://www.siemens.com/cert/operational-guidelines-industrial-security), and to follow the recommendations in the product manuals.

Additional information on Industrial Security by Siemens can be found at: https://www.siemens.com/industrialsecurity

PRODUCT DESCRIPTION

SIMOTICS CONNECT 400 is a connector and sensor box, mounted on low-voltage motors to provide analytics data for the MindSphere application SIDRIVE IQ Fleet.

VULNERABILITY CLASSIFICATION

The vulnerability classification has been performed by using the CVSS scoring system in version 3.1 (CVSS v3.1) (https://www.first.org/cvss). The CVSS environmental score is specific to the customer’s environment and will impact the overall CVSS score. The environmental score should therefore be individually defined by the customer to accomplish final scoring.

An additional classification has been performed using the CWE classification, a community-developed list of common software security weaknesses. This serves as a common language and as a baseline for weakness identification, mitigation, and prevention efforts. A detailed list of CWE classes can be found at: https://cwe.mitre.org/.

Vulnerability CVE-2020-27736

The DNS domain name label parsing functionality does not properly validate the null-terminated name in DNS-responses. The parsing of malformed responses could result in a read past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to cause a denial-of-service condition or leak the read memory.

CVSS v3.1 Base Score	6.5
CVSS Vector	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H/E:P/RL:O/RC:C
CWE:	CWE-170: Improper Null Termination

Vulnerability CVE-2020-27737

The DNS response parsing functionality does not properly validate various length and counts of the records. The parsing of malformed responses could result in a read past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to cause a denial-of-service condition or leak the memory past the allocated structure.

CVSS v3.1 Base Score	6.5
CVSS Vector	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H/E:P/RL:O/RC:C
CWE:	CWE-125: Out-of-bounds Read

Vulnerability CVE-2020-27738

The DNS domain name record decompression functionality does not properly validate the pointer offset values. The parsing of malformed responses could result in a read access past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to cause a denial-of-service condition.

CVSS v3.1 Base Score	6.5
CVSS Vector	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H/E:P/RL:O/RC:C
CWE:	CWE-788: Access of Memory Location After End of Buffer

Vulnerability CVE-2021-25677

The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.

CVSS v3.1 Base Score	5.3
CVSS Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C
CWE:	CWE-330: Use of Insufficiently Random Values

ACKNOWLEDGMENTS

Siemens thanks the following parties for their efforts:

Daniel dos Santos from Forescout Technologies Inc. for coordinated disclosure

ADDITIONAL INFORMATION

For further inquiries on security vulnerabilities in Siemens products and solutions, please contact the Siemens ProductCERT:

https://www.siemens.com/cert/advisories

HISTORY DATA

V1.0 (2021-04-13): Publication Date

V1.1 (2022-03-08): Added solution for CVE-2021-25677

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SSA-669158