ICSA-21-103-05
Vulnerability from csaf_cisa
Published
2021-04-13 00:00
Modified
2025-03-11 00:00
Summary
Siemens Nucleus Products IPv6 Stack

Notes

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.
General 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
Additional Resources
For further inquiries on security vulnerabilities in Siemens products and solutions, please contact the Siemens ProductCERT: https://www.siemens.com/cert/advisories
Terms of Use
The use of Siemens Security Advisories is subject to the terms and conditions listed on: https://www.siemens.com/productcert/terms-of-use.
Legal Notice
All information products included in https://us-cert.cisa.gov/ics are provided "as is" for informational purposes only. The Department of Homeland Security (DHS) does not provide any warranties of any kind regarding any information contained within. DHS does not endorse any commercial product or service, referenced in this product or otherwise. Further dissemination of this product is governed by the Traffic Light Protocol (TLP) marking in the header. For more information about TLP, see https://us-cert.cisa.gov/tlp/.
Advisory Conversion Disclaimer
This CISA CSAF advisory was converted from Siemens ProductCERT's CSAF advisory.
Critical infrastructure sectors
Critical Manufacturing, Transportation Systems, Energy, Healthcare and Public Health, Financial Services, Government Services and Facilities
Countries/areas deployed
Worldwide
Company headquarters location
Germany
Recommended Practices
CISA recommends users take defensive measures to minimize the exploitation risk of this vulnerability.
Recommended Practices
Minimize network exposure for all control system devices and/or systems, and ensure they are not accessible from the internet.
Recommended Practices
Locate control system networks and remote devices behind firewalls and isolate them from business networks.
Recommended Practices
When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most recent version available. Also recognize VPN is only as secure as its connected devices.
Recommended Practices
CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
Recommended Practices
CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
Recommended Practices
CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets. Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.
Recommended Practices
Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.


To clipboard 

{
  "document": {
    "acknowledgments": [
      {
        "organization": "Siemens ProductCERT",
        "summary": "reporting these vulnerabilities to CISA."
      }
    ],
    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Disclosure is not limited",
      "tlp": {
        "label": "WHITE",
        "url": "https://us-cert.cisa.gov/tlp/"
      }
    },
    "lang": "en",
    "notes": [
      {
        "category": "summary",
        "text": "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.\n\nSiemens 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.",
        "title": "Summary"
      },
      {
        "category": "general",
        "text": "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\u0027 operational guidelines for Industrial Security (Download: \nhttps://www.siemens.com/cert/operational-guidelines-industrial-security), and to follow the recommendations in the product manuals.\nAdditional information on Industrial Security by Siemens can be found at: https://www.siemens.com/industrialsecurity",
        "title": "General Recommendations"
      },
      {
        "category": "general",
        "text": "For further inquiries on security vulnerabilities in Siemens products and solutions, please contact the Siemens ProductCERT: https://www.siemens.com/cert/advisories",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The use of Siemens Security Advisories is subject to the terms and conditions listed on: https://www.siemens.com/productcert/terms-of-use.",
        "title": "Terms of Use"
      },
      {
        "category": "legal_disclaimer",
        "text": "All information products included in https://us-cert.cisa.gov/ics are provided \"as is\" for informational purposes only. The Department of Homeland Security (DHS) does not provide any warranties of any kind regarding any information contained within. DHS does not endorse any commercial product or service, referenced in this product or otherwise. Further dissemination of this product is governed by the Traffic Light Protocol (TLP) marking in the header. For more information about TLP, see https://us-cert.cisa.gov/tlp/.",
        "title": "Legal Notice"
      },
      {
        "category": "other",
        "text": "This CISA CSAF advisory was converted from Siemens ProductCERT\u0027s CSAF advisory.",
        "title": "Advisory Conversion Disclaimer"
      },
      {
        "category": "other",
        "text": "Critical Manufacturing, Transportation Systems, Energy, Healthcare and Public Health, Financial Services, Government Services and Facilities",
        "title": "Critical infrastructure sectors"
      },
      {
        "category": "other",
        "text": "Worldwide",
        "title": "Countries/areas deployed"
      },
      {
        "category": "other",
        "text": "Germany",
        "title": "Company headquarters location"
      },
      {
        "category": "general",
        "text": "CISA recommends users take defensive measures to minimize the exploitation risk of this vulnerability.",
        "title": "Recommended Practices"
      },
      {
        "category": "general",
        "text": "Minimize network exposure for all control system devices and/or systems, and ensure they are not accessible from the internet.",
        "title": "Recommended Practices"
      },
      {
        "category": "general",
        "text": "Locate control system networks and remote devices behind firewalls and isolate them from business networks.",
        "title": "Recommended Practices"
      },
      {
        "category": "general",
        "text": "When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most recent version available. Also recognize VPN is only as secure as its connected devices.",
        "title": "Recommended Practices"
      },
      {
        "category": "general",
        "text": "CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.",
        "title": "Recommended Practices"
      },
      {
        "category": "general",
        "text": "CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.",
        "title": "Recommended Practices"
      },
      {
        "category": "general",
        "text": "CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets. Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.",
        "title": "Recommended Practices"
      },
      {
        "category": "general",
        "text": "Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.",
        "title": "Recommended Practices"
      }
    ],
    "publisher": {
      "category": "other",
      "contact_details": "central@cisa.dhs.gov",
      "name": "CISA",
      "namespace": "https://www.cisa.gov/"
    },
    "references": [
      {
        "category": "self",
        "summary": "SSA-248289: Denial of Service Vulnerabilities in the IPv6 Stack of Nucleus RTOS - CSAF Version",
        "url": "https://cert-portal.siemens.com/productcert/csaf/ssa-248289.json"
      },
      {
        "category": "self",
        "summary": "SSA-248289: Denial of Service Vulnerabilities in the IPv6 Stack of Nucleus RTOS - HTML Version",
        "url": "https://cert-portal.siemens.com/productcert/html/ssa-248289.html"
      },
      {
        "category": "self",
        "summary": "ICS Advisory ICSA-21-103-05 JSON",
        "url": "https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2021/icsa-21-103-05.json"
      },
      {
        "category": "self",
        "summary": "ICS Advisory ICSA-21-103-05 - Web Version",
        "url": "https://www.cisa.gov/news-events/ics-advisories/icsa-21-103-05"
      },
      {
        "category": "external",
        "summary": "Recommended Practices",
        "url": "https://www.cisa.gov/uscert/ics/alerts/ICS-ALERT-10-301-01"
      },
      {
        "category": "external",
        "summary": "Recommended Practices",
        "url": "https://www.cisa.gov/resources-tools/resources/ics-recommended-practices"
      },
      {
        "category": "external",
        "summary": "Recommended Practices",
        "url": "https://www.cisa.gov/topics/industrial-control-systems"
      },
      {
        "category": "external",
        "summary": "Recommended Practices",
        "url": "https://us-cert.cisa.gov/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf"
      },
      {
        "category": "external",
        "summary": "Recommended Practices",
        "url": "https://www.cisa.gov/sites/default/files/publications/Cybersecurity_Best_Practices_for_Industrial_Control_Systems.pdf"
      },
      {
        "category": "external",
        "summary": "Recommended Practices",
        "url": "https://www.cisa.gov/uscert/ics/tips/ICS-TIP-12-146-01B"
      }
    ],
    "title": "Siemens Nucleus Products IPv6 Stack",
    "tracking": {
      "current_release_date": "2025-03-11T00:00:00.000000Z",
      "generator": {
        "date": "2025-03-06T09:03:00.000000Z",
        "engine": {
          "name": "CISA CSAF Generator",
          "version": "1.0.0"
        }
      },
      "id": "ICSA-21-103-05",
      "initial_release_date": "2021-04-13T00:00:00.000000Z",
      "revision_history": [
        {
          "date": "2021-04-13T00:00:00.000000Z",
          "legacy_version": "1.0",
          "number": "1",
          "summary": "Publication Date"
        },
        {
          "date": "2021-11-09T00:00:00.000000Z",
          "legacy_version": "1.1",
          "number": "2",
          "summary": "Added solution for Nucleus ReadyStart V3; consolidated list of products"
        },
        {
          "date": "2024-02-13T00:00:00.000000Z",
          "legacy_version": "1.2",
          "number": "3",
          "summary": "Renamed Capital VSTAR to Capital Embedded AR Classic; added fix and mitigation for Capital Embedded AR Classic; added CVSSv4.0 vector and score"
        },
        {
          "date": "2025-03-11T00:00:00.000000Z",
          "legacy_version": "1.3",
          "number": "4",
          "summary": "Updated remediation of Capital Embedded AR Classic 431-422 as no fix planned"
        }
      ],
      "status": "final",
      "version": "4"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:all/*",
                "product": {
                  "name": "Capital Embedded AR Classic 431-422",
                  "product_id": "CSAFPID-0001"
                }
              }
            ],
            "category": "product_name",
            "name": "Capital Embedded AR Classic 431-422"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:all/\u003cV2303",
                "product": {
                  "name": "Capital Embedded AR Classic R20-11",
                  "product_id": "CSAFPID-0002"
                }
              }
            ],
            "category": "product_name",
            "name": "Capital Embedded AR Classic R20-11"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:all/*",
                "product": {
                  "name": "Nucleus NET",
                  "product_id": "CSAFPID-0003"
                }
              }
            ],
            "category": "product_name",
            "name": "Nucleus NET"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:all/\u003cV2017.02.4",
                "product": {
                  "name": "Nucleus ReadyStart V3",
                  "product_id": "CSAFPID-0004"
                }
              }
            ],
            "category": "product_name",
            "name": "Nucleus ReadyStart V3"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:all/\u003cV4.1.0",
                "product": {
                  "name": "Nucleus ReadyStart V4",
                  "product_id": "CSAFPID-0005"
                }
              }
            ],
            "category": "product_name",
            "name": "Nucleus ReadyStart V4"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:all/*",
                "product": {
                  "name": "Nucleus Source Code",
                  "product_id": "CSAFPID-0006"
                }
              }
            ],
            "category": "product_name",
            "name": "Nucleus Source Code"
          }
        ],
        "category": "vendor",
        "name": "Siemens"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2021-25663",
      "cwe": {
        "id": "CWE-835",
        "name": "Loop with Unreachable Exit Condition (\u0027Infinite Loop\u0027)"
      },
      "notes": [
        {
          "category": "summary",
          "text": "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.",
          "title": "Summary"
        }
      ],
      "product_status": {
        "known_affected": [
          "CSAFPID-0001",
          "CSAFPID-0002",
          "CSAFPID-0003",
          "CSAFPID-0004",
          "CSAFPID-0005",
          "CSAFPID-0006"
        ]
      },
      "remediations": [
        {
          "category": "mitigation",
          "details": "Contact customer support or your local Nucleus Sales team for mitigation advice",
          "product_ids": [
            "CSAFPID-0003"
          ]
        },
        {
          "category": "mitigation",
          "details": "Disable IPv6 functionality, if feature not used, by deselecting the TcpIpIpV6General/IpV6Enabled Pre-Compile configuration option",
          "product_ids": [
            "CSAFPID-0001",
            "CSAFPID-0002"
          ]
        },
        {
          "category": "mitigation",
          "details": "Update to the latest version of Nucleus ReadyStart V3 or V4",
          "product_ids": [
            "CSAFPID-0003"
          ]
        },
        {
          "category": "no_fix_planned",
          "details": "Currently no fix is planned",
          "product_ids": [
            "CSAFPID-0001",
            "CSAFPID-0003"
          ]
        },
        {
          "category": "vendor_fix",
          "details": "Update to V2017.02.4 or later version",
          "product_ids": [
            "CSAFPID-0004"
          ]
        },
        {
          "category": "vendor_fix",
          "details": "Update to V2303 or later version",
          "product_ids": [
            "CSAFPID-0002"
          ]
        },
        {
          "category": "vendor_fix",
          "details": "Update to V4.1.0 or later version",
          "product_ids": [
            "CSAFPID-0005"
          ]
        },
        {
          "category": "vendor_fix",
          "details": "Contact customer support to receive patch and update information",
          "product_ids": [
            "CSAFPID-0006"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "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",
            "version": "3.1"
          },
          "products": [
            "CSAFPID-0001",
            "CSAFPID-0002",
            "CSAFPID-0003",
            "CSAFPID-0004",
            "CSAFPID-0005",
            "CSAFPID-0006"
          ]
        }
      ],
      "title": "CVE-2021-25663"
    },
    {
      "cve": "CVE-2021-25664",
      "cwe": {
        "id": "CWE-835",
        "name": "Loop with Unreachable Exit Condition (\u0027Infinite Loop\u0027)"
      },
      "notes": [
        {
          "category": "summary",
          "text": "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.",
          "title": "Summary"
        }
      ],
      "product_status": {
        "known_affected": [
          "CSAFPID-0001",
          "CSAFPID-0002",
          "CSAFPID-0003",
          "CSAFPID-0004",
          "CSAFPID-0005",
          "CSAFPID-0006"
        ]
      },
      "remediations": [
        {
          "category": "mitigation",
          "details": "Contact customer support or your local Nucleus Sales team for mitigation advice",
          "product_ids": [
            "CSAFPID-0003"
          ]
        },
        {
          "category": "mitigation",
          "details": "Disable IPv6 functionality, if feature not used, by deselecting the TcpIpIpV6General/IpV6Enabled Pre-Compile configuration option",
          "product_ids": [
            "CSAFPID-0001",
            "CSAFPID-0002"
          ]
        },
        {
          "category": "mitigation",
          "details": "Update to the latest version of Nucleus ReadyStart V3 or V4",
          "product_ids": [
            "CSAFPID-0003"
          ]
        },
        {
          "category": "no_fix_planned",
          "details": "Currently no fix is planned",
          "product_ids": [
            "CSAFPID-0001",
            "CSAFPID-0003"
          ]
        },
        {
          "category": "vendor_fix",
          "details": "Update to V2017.02.4 or later version",
          "product_ids": [
            "CSAFPID-0004"
          ]
        },
        {
          "category": "vendor_fix",
          "details": "Update to V2303 or later version",
          "product_ids": [
            "CSAFPID-0002"
          ]
        },
        {
          "category": "vendor_fix",
          "details": "Update to V4.1.0 or later version",
          "product_ids": [
            "CSAFPID-0005"
          ]
        },
        {
          "category": "vendor_fix",
          "details": "Contact customer support to receive patch and update information",
          "product_ids": [
            "CSAFPID-0006"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "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",
            "version": "3.1"
          },
          "products": [
            "CSAFPID-0001",
            "CSAFPID-0002",
            "CSAFPID-0003",
            "CSAFPID-0004",
            "CSAFPID-0005",
            "CSAFPID-0006"
          ]
        }
      ],
      "title": "CVE-2021-25664"
    }
  ]
}


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