{
  "document": {
    "acknowledgments": [
      {
        "summary": "This vulnerability was found during the resolution of a Cisco TAC support case."
      }
    ],
    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "notes": [
      {
        "category": "summary",
        "text": "A vulnerability in the processing of SSH connections for multi-instance deployments of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on the affected device.\r\n\r\nThis vulnerability is due to a lack of proper error handling when an SSH session fails to be established. An attacker could exploit this vulnerability by sending a high rate of crafted SSH connections to the instance. A successful exploit could allow the attacker to cause resource exhaustion, which causes a DoS condition on the affected device. The device must be manually reloaded to recover.\r\n\r\nCisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.\r\n\r\n\r\n\r\nThis advisory is part of the October 2021 release of the Cisco ASA, FTD, and FMC Security Advisory Bundled publication. For a complete list of the advisories and links to them, see Cisco Event Response: October 2021 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication [\"https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-74773\"].",
        "title": "Summary"
      },
      {
        "category": "general",
        "text": "This vulnerability affects devices if they are running a vulnerable release of Cisco FTD Software that is configured for multi-instance operation. Multi-instance configuration support was introduced in Cisco FTD Software Release 6.3.0; earlier releases are not affected by this multi-instance vulnerability.\r\n\r\nThe only Cisco FTD Software platforms that support multi-instance operation are the following:\r\n\r\nFirepower 4100 Series Security Appliances\r\nFirepower 9300 Series Security Appliances\r\n\r\nNote: Affected devices are vulnerable only when accessed from an IP address in the configured SSH command range. The SSH service is enabled by default on all devices that run Cisco FTD Software.\r\n\r\nFor information about which Cisco software releases are vulnerable, see the Fixed Software [\"#fs\"] section of this advisory.\r\n\r\nDetermine the Device Configuration\r\n\r\n\r\nTo determine whether a device is providing multi-instance services, log in to the Cisco FXOS CLI and use the show app-instance command within the ssa scope. If the Deploy Type field has a value of Container, application instances are present and the device is vulnerable. The following example shows the command output for a vulnerable device:\r\n\r\nfirepower# scope ssa\r\nfirepower /ssa # show app-instance\r\n\r\n                                App Name              Identifier              Slot ID              Admin State              Oper State              Running Version              Startup Version              Deploy Type              Turbo Mode              Profile Name              Cluster State              Cluster Role                                  -----              -------              ------              ------              -----              -------              -------              ------              -----              -----              -------              -------                                  ftd              ftd1              1              Enabled              Online              6.2.3.14              6.2.3.14              Native              No                             Not Applicable              None                                  ftd              ftd2-1              2              Enabled              Online              6.4.0.4              6.4.0.4              Container              No              mid              Not Applicable",
        "title": "Vulnerable Products"
      },
      {
        "category": "general",
        "text": "Only products listed in the Vulnerable Products [\"#vp\"] section of this advisory are known to be affected by this vulnerability.\r\n\r\nCisco has confirmed that this vulnerability does not affect Cisco Adaptive Security Appliance (ASA) Software or Cisco Firepower Management Center (FMC) Software.",
        "title": "Products Confirmed Not Vulnerable"
      },
      {
        "category": "general",
        "text": "There are no workarounds that address this vulnerability.\r\n\r\nHowever, as a mitigation, administrators can allow only trusted networks and hosts to have SSH access to the FTD management IP. This will limit the attack surface of this vulnerability. See Harden FTD User Access [\"https://www.cisco.com/c/en/us/td/docs/security/firepower/640/hardening/ftd/FTD_Hardening_Guide_v64.html#id_106774https://www.cisco.com/c/en/us/td/docs/security/firepower/640/hardening/ftd/FTD_Hardening_Guide_v64.html#id_106774\"] for more information.\r\n\r\nWhile this mitigation has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.",
        "title": "Workarounds"
      },
      {
        "category": "general",
        "text": "Cisco has released free software updates that address the vulnerability described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license:\r\nhttps://www.cisco.com/c/en/us/products/end-user-license-agreement.html [\"https://www.cisco.com/c/en/us/products/end-user-license-agreement.html\"]\r\n\r\nAdditionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades.\r\n\r\nWhen considering software upgrades [\"https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#fixes\"], customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page [\"https://www.cisco.com/go/psirt\"], to determine exposure and a complete upgrade solution.\r\n\r\nIn all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.\r\n  Customers Without Service Contracts\r\nCustomers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html [\"https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html\"]\r\n\r\nCustomers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.\r\n      Fixed Releases\r\nIn the following table(s), the left column lists Cisco software releases. The center column indicates whether a release is affected by the vulnerability described in this advisory and the first release that includes the fix for this vulnerability. The right column indicates whether a release is affected by any of the Critical or High SIR vulnerabilities described in this bundle and which release includes fixes for those vulnerabilities.\r\n\r\nFTD Software\r\n                                Cisco FTD Release              First Fixed Release for This Vulnerability              First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories                                              6.2.2 and earlier 1              Not vulnerable.              Migrate to a fixed release.                                  6.2.3              Not vulnerable.              Migrate to a fixed release.                                  6.3.0 1              Migrate to a fixed release.              Migrate to a fixed release.                                  6.4.0              6.4.0.13 (Nov 2021)              6.4.0.13 (Nov 2021)                                  6.5.0 1              Migrate to a fixed release.              Migrate to a fixed release.                                  6.6.0              6.6.5              6.6.5.1 (Nov 2021)                                  6.7.0              6.7.0.3 (Jan 2022)              6.7.0.3 (Jan 2022)                                  7.0.0              7.0.1              7.0.1\r\n1. Cisco FMC and FTD Software releases 6.2.2 and earlier, as well as releases 6.3.0 and 6.5.0, have reached end of software maintenance [\"https://www.cisco.com/c/en/us/products/eos-eol-listing.html\"]. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.\r\nFor instructions on upgrading your FTD device, see Cisco Firepower Management Center Upgrade Guide [\"https://www.cisco.com/c/en/us/td/docs/security/firepower/upgrade/fpmc-upgrade-guide/getting_started.html\"].\r\n\r\nThe Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.",
        "title": "Fixed Software"
      },
      {
        "category": "general",
        "text": "To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy [\"https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html\"]. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.",
        "title": "Vulnerability Policy"
      },
      {
        "category": "general",
        "text": "The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.",
        "title": "Exploitation and Public Announcements"
      },
      {
        "category": "general",
        "text": "This vulnerability was found during the resolution of a Cisco TAC support case.",
        "title": "Source"
      },
      {
        "category": "legal_disclaimer",
        "text": "THIS DOCUMENT IS PROVIDED ON AN \"AS IS\" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.\r\n\r\nA standalone copy or paraphrase of the text of this document that omits the distribution URL is an uncontrolled copy and may lack important information or contain factual errors. The information in this document is intended for end users of Cisco products.",
        "title": "Legal Disclaimer"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "psirt@cisco.com",
      "issuing_authority": "Cisco PSIRT",
      "name": "Cisco",
      "namespace": "https://wwww.cisco.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "Cisco Firepower Threat Defense Software SSH Connections Denial of Service Vulnerability",
        "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-dos-rUDseW3r"
      },
      {
        "category": "external",
        "summary": "Cisco Event Response: October 2021 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication",
        "url": "https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-74773"
      },
      {
        "category": "external",
        "summary": "Cisco Security Vulnerability Policy",
        "url": "https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html"
      },
      {
        "category": "external",
        "summary": "https://www.cisco.com/c/en/us/products/end-user-license-agreement.html",
        "url": "https://www.cisco.com/c/en/us/products/end-user-license-agreement.html"
      },
      {
        "category": "external",
        "summary": "considering software upgrades",
        "url": "https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#fixes"
      },
      {
        "category": "external",
        "summary": "Cisco\u0026nbsp;Security Advisories page",
        "url": "https://www.cisco.com/go/psirt"
      },
      {
        "category": "external",
        "summary": "https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html",
        "url": "https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html"
      },
      {
        "category": "external",
        "summary": "end of software maintenance",
        "url": "https://www.cisco.com/c/en/us/products/eos-eol-listing.html"
      },
      {
        "category": "external",
        "summary": "Cisco\u0026nbsp;Firepower Management Center Upgrade Guide",
        "url": "https://www.cisco.com/c/en/us/td/docs/security/firepower/upgrade/fpmc-upgrade-guide/getting_started.html"
      }
    ],
    "title": "Cisco Firepower Threat Defense Software SSH Connections Denial of Service Vulnerability",
    "tracking": {
      "current_release_date": "2021-10-27T16:00:00+00:00",
      "generator": {
        "date": "2024-05-10T23:10:56+00:00",
        "engine": {
          "name": "TVCE"
        }
      },
      "id": "cisco-sa-ftd-dos-rUDseW3r",
      "initial_release_date": "2021-10-27T16:00:00+00:00",
      "revision_history": [
        {
          "date": "2021-10-27T15:39:36+00:00",
          "number": "1.0.0",
          "summary": "Initial public release."
        }
      ],
      "status": "final",
      "version": "1.0.0"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "category": "product_family",
            "name": "Cisco Adaptive Security Appliance (ASA) Software",
            "product": {
              "name": "Cisco Adaptive Security Appliance (ASA) Software ",
              "product_id": "CSAFPID-6588"
            }
          },
          {
            "category": "product_family",
            "name": "Cisco Firepower Threat Defense Software",
            "product": {
              "name": "Cisco Firepower Threat Defense Software ",
              "product_id": "CSAFPID-220203"
            }
          }
        ],
        "category": "vendor",
        "name": "Cisco"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2021-34781",
      "ids": [
        {
          "system_name": "Cisco Bug ID",
          "text": "CSCvy13543"
        }
      ],
      "notes": [
        {
          "category": "other",
          "text": "Complete.",
          "title": "Affected Product Comprehensiveness"
        }
      ],
      "product_status": {
        "known_affected": [
          "CSAFPID-6588",
          "CSAFPID-220203"
        ]
      },
      "release_date": "2021-10-27T16:00:00+00:00",
      "remediations": [
        {
          "category": "vendor_fix",
          "details": "Cisco has released software updates that address this vulnerability.",
          "product_ids": [
            "CSAFPID-220203",
            "CSAFPID-6588"
          ],
          "url": "https://software.cisco.com"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "baseScore": 8.6,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
            "version": "3.1"
          },
          "products": [
            "CSAFPID-6588",
            "CSAFPID-220203"
          ]
        }
      ],
      "title": "Cisco Adaptive Security Appliances and Firepower Threat Defense Software Denial of Service Vulnerability"
    }
  ]
}