{
  "GSD": {
    "alias": "CVE-2021-43890",
    "description": "Windows AppX Installer Spoofing Vulnerability",
    "id": "GSD-2021-43890"
  },
  "gsd": {
    "metadata": {
      "exploitCode": "unknown",
      "remediation": "unknown",
      "reportConfidence": "confirmed",
      "type": "vulnerability"
    },
    "osvSchema": {
      "aliases": [
        "CVE-2021-43890"
      ],
      "details": "Windows AppX Installer Spoofing Vulnerability",
      "id": "GSD-2021-43890",
      "modified": "2023-12-13T01:23:25.892349Z",
      "schema_version": "1.4.0"
    }
  },
  "namespaces": {
    "cisa.gov": {
      "cveID": "CVE-2021-43890",
      "dateAdded": "2021-12-15",
      "dueDate": "2021-12-29",
      "product": "Windows",
      "requiredAction": "Apply updates per vendor instructions.",
      "shortDescription": "Microsoft Windows AppX Installer contains a spoofing vulnerability which has a high impacts to confidentiality, integrity, and availability.",
      "vendorProject": "Microsoft",
      "vulnerabilityName": "Microsoft Windows AppX Installer Spoofing Vulnerability"
    },
    "cve.org": {
      "CVE_data_meta": {
        "ASSIGNER": "secure@microsoft.com",
        "ID": "CVE-2021-43890",
        "STATE": "PUBLIC"
      },
      "affects": {
        "vendor": {
          "vendor_data": [
            {
              "product": {
                "product_data": [
                  {
                    "product_name": "App Installer",
                    "version": {
                      "version_data": [
                        {
                          "version_affected": "\u003c",
                          "version_name": "1.0.0.0",
                          "version_value": "publication"
                        }
                      ]
                    }
                  }
                ]
              },
              "vendor_name": "Microsoft"
            }
          ]
        }
      },
      "data_format": "MITRE",
      "data_type": "CVE",
      "data_version": "4.0",
      "description": {
        "description_data": [
          {
            "lang": "eng",
            "value": "\u003cp\u003eWe have investigated reports of a spoofing vulnerability in AppX installer that affects Microsoft Windows. Microsoft is aware of attacks that attempt to exploit this vulnerability by using specially crafted packages that include the malware family known as Emotet/Trickbot/Bazaloader.\u003c/p\u003e\n\u003cp\u003eAn attacker could craft a malicious attachment to be used in phishing campaigns. The attacker would then have to convince the user to open the specially crafted attachment. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.\u003c/p\u003e\n\u003cp\u003ePlease see the \u003cstrong\u003eSecurity Updates\u003c/strong\u003e table for the link to the updated app. Alternatively you can download and install the Installer using the links provided in the \u003cstrong\u003eFAQ\u003c/strong\u003e section.\u003c/p\u003e\n\u003cp\u003ePlease see the \u003cstrong\u003eMitigations\u003c/strong\u003e and \u003cstrong\u003eWorkaround\u003c/strong\u003e sections for important information about steps you can take to protect your system from this vulnerability.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDecember 27 2023 Update:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn recent months, Microsoft Threat Intelligence has seen an increase in activity from threat actors leveraging social engineering and phishing techniques to target Windows OS users and utilizing the \u003ca href=\"https://learn.microsoft.com/en-us/windows/msix/app-installer/installing-windows10-apps-web\"\u003ems-appinstaller URI scheme\u003c/a\u003e.\u003c/p\u003e\n\u003cp\u003eTo address this increase in activity, we have updated the App Installer to disable the ms-appinstaller protocol by default and recommend other potential mitigations.\u003c/p\u003e\n"
          }
        ]
      },
      "impact": {
        "cvss": [
          {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C",
            "version": "3.1"
          }
        ]
      },
      "problemtype": {
        "problemtype_data": [
          {
            "description": [
              {
                "lang": "eng",
                "value": "Spoofing"
              }
            ]
          }
        ]
      },
      "references": {
        "reference_data": [
          {
            "name": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43890",
            "refsource": "MISC",
            "url": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43890"
          },
          {
            "name": "https://www.bleepingcomputer.com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/",
            "refsource": "MISC",
            "url": "https://www.bleepingcomputer.com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/"
          },
          {
            "name": "https://thehackernews.com/2023/12/microsoft-disables-msix-app-installer.html",
            "refsource": "MISC",
            "url": "https://thehackernews.com/2023/12/microsoft-disables-msix-app-installer.html"
          },
          {
            "name": "https://www.microsoft.com/en-us/security/blog/2023/12/28/financially-motivated-threat-actors-misusing-app-installer/",
            "refsource": "MISC",
            "url": "https://www.microsoft.com/en-us/security/blog/2023/12/28/financially-motivated-threat-actors-misusing-app-installer/"
          },
          {
            "name": "https://github.com/ChrisTitusTech/winutil/pull/26",
            "refsource": "MISC",
            "url": "https://github.com/ChrisTitusTech/winutil/pull/26"
          }
        ]
      }
    },
    "nvd.nist.gov": {
      "cve": {
        "cisaActionDue": "2021-12-29",
        "cisaExploitAdd": "2021-12-15",
        "cisaRequiredAction": "Apply updates per vendor instructions.",
        "cisaVulnerabilityName": "Microsoft Windows AppX Installer Spoofing Vulnerability",
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:a:microsoft:app_installer:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "F08CBD8F-D993-4175-A2FF-0A0C37F7AFD0",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              },
              {
                "cpeMatch": [
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            ],
            "operator": "AND"
          }
        ],
        "descriptions": [
          {
            "lang": "en",
            "value": "\u003cp\u003eWe have investigated reports of a spoofing vulnerability in AppX installer that affects Microsoft Windows. Microsoft is aware of attacks that attempt to exploit this vulnerability by using specially crafted packages that include the malware family known as Emotet/Trickbot/Bazaloader.\u003c/p\u003e\n\u003cp\u003eAn attacker could craft a malicious attachment to be used in phishing campaigns. The attacker would then have to convince the user to open the specially crafted attachment. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.\u003c/p\u003e\n\u003cp\u003ePlease see the \u003cstrong\u003eSecurity Updates\u003c/strong\u003e table for the link to the updated app. Alternatively you can download and install the Installer using the links provided in the \u003cstrong\u003eFAQ\u003c/strong\u003e section.\u003c/p\u003e\n\u003cp\u003ePlease see the \u003cstrong\u003eMitigations\u003c/strong\u003e and \u003cstrong\u003eWorkaround\u003c/strong\u003e sections for important information about steps you can take to protect your system from this vulnerability.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDecember 27 2023 Update:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn recent months, Microsoft Threat Intelligence has seen an increase in activity from threat actors leveraging social engineering and phishing techniques to target Windows OS users and utilizing the \u003ca href=\"https://learn.microsoft.com/en-us/windows/msix/app-installer/installing-windows10-apps-web\"\u003ems-appinstaller URI scheme\u003c/a\u003e.\u003c/p\u003e\n\u003cp\u003eTo address this increase in activity, we have updated the App Installer to disable the ms-appinstaller protocol by default and recommend other potential mitigations.\u003c/p\u003e\n"
          },
          {
            "lang": "es",
            "value": "Una vulnerabilidad de Suplantaci\u00f3n de Identidad de Windows AppX Installer"
          }
        ],
        "id": "CVE-2021-43890",
        "lastModified": "2023-12-30T07:15:08.147",
        "metrics": {
          "cvssMetricV2": [
            {
              "acInsufInfo": false,
              "baseSeverity": "MEDIUM",
              "cvssData": {
                "accessComplexity": "MEDIUM",
                "accessVector": "NETWORK",
                "authentication": "SINGLE",
                "availabilityImpact": "PARTIAL",
                "baseScore": 6.0,
                "confidentialityImpact": "PARTIAL",
                "integrityImpact": "PARTIAL",
                "vectorString": "AV:N/AC:M/Au:S/C:P/I:P/A:P",
                "version": "2.0"
              },
              "exploitabilityScore": 6.8,
              "impactScore": 6.4,
              "obtainAllPrivilege": false,
              "obtainOtherPrivilege": false,
              "obtainUserPrivilege": false,
              "source": "nvd@nist.gov",
              "type": "Primary",
              "userInteractionRequired": true
            }
          ],
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "HIGH",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 7.1,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "REQUIRED",
                "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.2,
              "impactScore": 5.9,
              "source": "nvd@nist.gov",
              "type": "Primary"
            },
            {
              "cvssData": {
                "attackComplexity": "HIGH",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 7.1,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "REQUIRED",
                "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.2,
              "impactScore": 5.9,
              "source": "secure@microsoft.com",
              "type": "Secondary"
            }
          ]
        },
        "published": "2021-12-15T15:15:11.207",
        "references": [
          {
            "source": "secure@microsoft.com",
            "url": "https://github.com/ChrisTitusTech/winutil/pull/26"
          },
          {
            "source": "secure@microsoft.com",
            "tags": [
              "Patch",
              "Vendor Advisory"
            ],
            "url": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43890"
          },
          {
            "source": "secure@microsoft.com",
            "url": "https://thehackernews.com/2023/12/microsoft-disables-msix-app-installer.html"
          },
          {
            "source": "secure@microsoft.com",
            "url": "https://www.bleepingcomputer.com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/"
          },
          {
            "source": "secure@microsoft.com",
            "url": "https://www.microsoft.com/en-us/security/blog/2023/12/28/financially-motivated-threat-actors-misusing-app-installer/"
          }
        ],
        "sourceIdentifier": "secure@microsoft.com",
        "vulnStatus": "Modified",
        "weaknesses": [
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            "description": [
              {
                "lang": "en",
                "value": "NVD-CWE-noinfo"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    }
  }
}