{
  "document": {
    "title": "SSA-201384: Predictable UDP Port Number Vulnerability (NAME:WRECK) in the DNS Module of Nucleus RTOS",
    "category": "Siemens Security Advisory",
    "csaf_version": "2.0",
    "publisher": {
      "name": "Siemens ProductCERT",
      "contact_details": "productcert@siemens.com",
      "category": "vendor",
      "namespace": "https://www.siemens.com"
    },
    "distribution": {
      "text": "Disclosure is not limited.",
      "tlp": {
        "label": "WHITE"
      }
    },
    "tracking": {
      "id": "SSA-201384",
      "status": "final",
      "version": "3",
      "revision_history": [
        {
          "number": "1",
          "legacy_version": "1.0",
          "date": "2021-04-13T00:00:00Z",
          "summary": "Publication Date"
        },
        {
          "number": "2",
          "legacy_version": "1.1",
          "date": "2021-11-09T00:00:00Z",
          "summary": "Consolidated list of products"
        },
        {
          "number": "3",
          "legacy_version": "1.2",
          "date": "2022-01-11T00:00:00Z",
          "summary": "Removed CAPITAL VSTAR as not affected"
        }
      ],
      "initial_release_date": "2021-04-13T00:00:00Z",
      "current_release_date": "2022-01-11T00:00:00Z",
      "generator": {
        "engine": {
          "name": "Siemens ProductCERT CSAF Generator",
          "version": "1"
        }
      }
    },
    "notes": [
      {
        "title": "Summary",
        "category": "summary",
        "text": "Security researchers discovered and disclosed 9 vulnerabilities in several DNS implementations, also known as “NAME:WRECK” vulnerabilities. The vulnerability described in this advisory is from this set.\n\nThe DNS client of of the networking component (Nucleus NET) in Nucleus Real-Time Operating System (RTOS) contains a vulnerability related to the handling of UDP port numbers in DNS requests that could allow an attacker to poison the DNS cache or spoof DNS resolving.\n\nSiemens 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."
      },
      {
        "title": "General Recommendations",
        "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' operational guidelines for Industrial Security (Download: https://www.siemens.com/cert/operational-guidelines-industrial-security), and to follow the recommendations in the product manuals.\n\nAdditional information on Industrial Security by Siemens can be found at: https://www.siemens.com/industrialsecurity"
      },
      {
        "title": "Additional Resources",
        "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": "Terms of Use",
        "category": "legal_disclaimer",
        "text": "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."
      }
    ],
    "references": [
      {
        "category": "self",
        "url": "https://cert-portal.siemens.com/productcert/pdf/ssa-201384.pdf",
        "summary": "SSA-201384: Predictable UDP Port Number Vulnerability (NAME:WRECK) in the DNS Module of Nucleus RTOS - PDF Version"
      },
      {
        "category": "self",
        "url": "https://cert-portal.siemens.com/productcert/txt/ssa-201384.txt",
        "summary": "SSA-201384: Predictable UDP Port Number Vulnerability (NAME:WRECK) in the DNS Module of Nucleus RTOS - TXT Version"
      },
      {
        "category": "self",
        "url": "https://cert-portal.siemens.com/productcert/csaf/ssa-201384.json",
        "summary": "SSA-201384: Predictable UDP Port Number Vulnerability (NAME:WRECK) in the DNS Module of Nucleus RTOS - CSAF Version"
      }
    ],
    "acknowledgments": [
      {
        "names": [
          "Daniel dos Santos"
        ],
        "organization": "Forescout Technologies Inc.",
        "summary": "coordinated disclosure"
      }
    ]
  },
  "product_tree": {
    "branches": [
      {
        "name": "Siemens",
        "category": "vendor",
        "branches": [
          {
            "name": "Nucleus NET",
            "category": "product_name",
            "branches": [
              {
                "name": "vers:all/*",
                "category": "product_version_range",
                "product": {
                  "product_id": "1",
                  "name": "Nucleus NET"
                }
              }
            ]
          },
          {
            "name": "Nucleus ReadyStart V3",
            "category": "product_name",
            "branches": [
              {
                "name": "< V2013.08",
                "category": "product_version_range",
                "product": {
                  "product_id": "2",
                  "name": "Nucleus ReadyStart V3"
                }
              }
            ]
          },
          {
            "name": "Nucleus Source Code",
            "category": "product_name",
            "branches": [
              {
                "name": "Versions including affected DNS modules",
                "category": "product_version_range",
                "product": {
                  "product_id": "3",
                  "name": "Nucleus Source Code"
                }
              }
            ]
          }
        ]
      }
    ]
  },
  "vulnerabilities": [
    {
      "title": "CVE-2021-27393",
      "notes": [
        {
          "title": "Summary",
          "category": "summary",
          "text": "The DNS client does not properly randomize UDP port numbers of DNS requests. That could allow an attacker to poison the DNS cache or spoof DNS resolving."
        }
      ],
      "cve": "CVE-2021-27393",
      "cwe": {
        "id": "CWE-330",
        "name": "Use of Insufficiently Random Values"
      },
      "product_status": {
        "known_affected": [
          "1",
          "2",
          "3"
        ]
      },
      "scores": [
        {
          "cvss_v3": {
            "version": "3.1",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "vectorString": "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"
          },
          "products": [
            "1",
            "2",
            "3"
          ]
        }
      ],
      "remediations": [
        {
          "product_ids": [
            "1"
          ],
          "category": "mitigation",
          "details": "Update to the latest version of Nucleus ReadyStart V3 or V4"
        },
        {
          "product_ids": [
            "1"
          ],
          "category": "mitigation",
          "details": "Contact customer support or your local Nucleus Sales team for mitigation advice"
        },
        {
          "product_ids": [
            "1"
          ],
          "category": "no_fix_planned",
          "details": "Currently no remediation is planned"
        },
        {
          "product_ids": [
            "2"
          ],
          "category": "vendor_fix",
          "details": "Update to V2013.08 or later version",
          "url": "https://support.sw.siemens.com/en-US/product/1009925838/"
        },
        {
          "product_ids": [
            "3"
          ],
          "category": "vendor_fix",
          "details": "Contact customer support to receive patch and update information"
        },
        {
          "product_ids": [
            "1",
            "2",
            "3"
          ],
          "category": "mitigation",
          "details": "Avoid using DNS client of affected versions"
        }
      ],
      "references": [
        {
          "url": "https://support.sw.siemens.com/en-US/product/1009925838/",
          "summary": "CVE-2021-27393 - Nucleus ReadyStart V3"
        },
        {
          "url": "https://cert-portal.siemens.com/productcert/mitre/CVE-2021-27393.json",
          "summary": "CVE-2021-27393 Mitre 5.0 json"
        }
      ]
    }
  ]
}