-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 # SSA-248289: Denial of Service Vulnerabilities in the IPv6 Stack of Nucleus RTOS Publication Date: 2021-04-13 Last Update: 2024-02-13 Current Version: 1.2 CVSS v3.1 Base Score: 7.5 CVSS v4.0 Base Score: 8.7 SUMMARY ======= The IPv6 stack of the networking component (Nucleus NET) in Nucleus Real-Time Operating System (RTOS) contains two vulnerabilities when processing IPv6 headers which could allow an attacker to cause a denial of service condition. Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens is preparing further fix versions and recommends countermeasures for products where fixes are not, or not yet available. AFFECTED PRODUCTS AND SOLUTION ============================== * Capital Embedded AR Classic 431-422 - Affected versions: All versions - Remediations: Currently no fix is available Disable IPv6 functionality, if feature not used, by deselecting the TcpIpIpV6General/IpV6Enabled Pre-Compile configuration option * Capital Embedded AR Classic R20-11 - Affected versions: All versions < V2303 - Remediations: Update to V2303 or later version Disable IPv6 functionality, if feature not used, by deselecting the TcpIpIpV6General/IpV6Enabled Pre-Compile configuration option * Nucleus NET - Affected versions: All versions - Remediations: Currently no fix is planned Update to the latest version of Nucleus ReadyStart V3 or V4 Contact customer support or your local Nucleus Sales team for mitigation advice * Nucleus ReadyStart V3 - Affected versions: All versions < V2017.02.4 - Remediation: Update to V2017.02.4 or later version - Download: https://support.sw.siemens.com/en- US/product/1009925838/ * Nucleus ReadyStart V4 - Affected versions: All versions < V4.1.0 - Remediation: Update to V4.1.0 or later version - Download: https://support.sw.siemens.com/en- US/product/1336134128/ * Nucleus Source Code - Affected versions: All versions including affected IPv6 stack - Remediation: Contact customer support to receive patch and update information WORKAROUNDS AND MITIGATIONS =========================== Product-specific remediations or mitigations can be found in the section "Affected Products and Solution". Please follow the "General Security Recommendations". 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 =================== 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 ("Nucleus PLUS") and supports a variety of processors and MCUs. Nucleus ReadyStart is a platform with integrated software IP, tools, and services ideal for applications where a small footprint, deterministic performance, and small code size are essential. 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. Capital Embedded AR Classic (formerly called Capital VSTAR), is a scalable AUTOSAR Classic software platform that meets ISO 26262 use cases for up to ASIL D. Versions are available for several recent AUTOSAR Classic releases, including 4.3.1 and 20-11. Although not based on Nucleus RTOS, Embedded AR Classic includes its networking module, Nucleus NET. VULNERABILITY DESCRIPTION ========================= This chapter describes all vulnerabilities (CVE-IDs) addressed in this security advisory. Wherever applicable, it also documents the product-specific impact of the individual vulnerabilities. * Vulnerability CVE-2021-25663 The function that processes IPv6 headers does not check the lengths of extension header options, allowing attackers to put this function into an infinite loop with crafted length values. CVSS v3.1 Base Score: 7.5 CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C CVSS v4.0 Base Score: 8.7 CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N CWE: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') * Vulnerability CVE-2021-25664 The function that processes the Hop-by-Hop extension header in IPv6 packets and its options lacks any checks against the length field of the header, allowing attackers to put the function into an infinite loop by supplying arbitrary length values. CVSS v3.1 Base Score: 7.5 CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C CVSS v4.0 Base Score: 8.7 CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N CWE: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') 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): Added solution for Nucleus ReadyStart V3; consolidated list of products V1.2 (2024-02-13): Renamed Capital VSTAR to Capital Embedded AR Classic; added fix and mitigation for Capital Embedded AR Classic; added CVSSv4.0 vector and score 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://www.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. 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