SSA-185699: Out of Bounds Write Vulnerabilities (NAME:WRECK) in the DNS Module of Nucleus RTOS
Publication Date:
2021-04-13
Last Update:
2022-01-11
Current Version:
V1.2
CVSS v3.1 Base Score:
8.1
SUMMARY
Security researchers discovered and disclosed 9 vulnerabilities in several DNS implementations, also known as “NAME:WRECK” vulnerabilities. The vulnerabilities described in this advisory are from this set.
The DNS client of the networking component (Nucleus NET) in Nucleus Real-Time Operating System (RTOS) contains two out of bounds write vulnerabilities in the handling of DNS responses that could allow an attacker to cause a denial-of-service condition or to remotely execute code.
Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where updates are not available.
AFFECTED PRODUCTS AND SOLUTION
Affected Product and Versions
Remediation
Nucleus NET:
All versions < V5.2
Currently no remediation is plannedWorkarounds and Mitigations
Nucleus Source Code:
Versions including affected DNS modules
Contact customer support to receive patch and update information
See further recommendations from section Workarounds and Mitigations
WORKAROUNDS AND MITIGATIONS
Siemens has identified the following specific workarounds and mitigations that customers can apply to reduce the risk:
Avoid using DNS client of affected versions
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
Capital VSTAR is an efficient implementation of the AUTOSAR standard. It is a complete solution including tools and a software platform to meet engineers’ needs, from creating ECU extract updates to software platform configurations.
Although not based on Nucleus RTOS, VSTAR includes its networking module, Nucleus NET.
Nucleus NET module incorporates a wide range of standard-compliant networking and communication protocols, drivers, and utilities to deliver full-featured network support in any embedded device. The networking functionality is fully integrated into the Nucleus RTOS and supports a variety of processors and MCUs.
Nucleus RTOS is a highly scalable micro-kernel based real-time operating system designed for scalability and reliability in systems spanning the range of aerospace, industrial, and medical applications. Since V3, Nucleus RTOS (incl. its modules, e.g. Nucleus NET) is an integral part of the Nucleus ReadyStart platform.
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-2020-15795
The DNS domain name label parsing functionality does not properly validate the names in DNS-responses. The parsing of malformed responses could result in a write past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to execute code in the context of the current process or cause a denial-of-service condition.
CVSS v3.1 Base Score
8.1
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C
CWE:
CWE-787: Out-of-bounds Write
Vulnerability CVE-2020-27009
The DNS domain name record decompression functionality does not properly validate the pointer offset values. The parsing of malformed responses could result in a write past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to execute code in the context of the current process or cause a denial-of-service condition.
CVSS v3.1 Base Score
8.1
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C
CWE:
CWE-823: Use of Out-of-range Pointer Offset
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 (2021-11-09): Consolidated list of products
V1.2 (2022-01-11): Removed CAPITAL VSTAR as not affected
TERMS OF USE
Siemens Security Advisories are subject to the terms and conditions contained in Siemens’ underlying
license terms or other applicable agreements previously agreed to with Siemens (hereinafter "License
Terms"). To the extent applicable to information, software or documentation made available in or through a Siemens Security Advisory, the Terms of Use of Siemens’
Global Website
https://new.siemens.com/terms_of_use ,
hereinafter "Terms of Use"), in particular Sections 8-10 of the Terms of Use, shall apply
additionally. In case of conflicts, the License Terms shall prevail over the Terms of Use.