{
  "document": {
    "acknowledgments": [
      {
        "names": [
          "bee13oy and bo13oy of \u003ca href=\"https://www.cyberkl.com/\"\u003eCyber Kunlun Lab\u003c/a\u003e"
        ]
      }
    ],
    "aggregate_severity": {
      "namespace": "https://www.microsoft.com/en-us/msrc/security-update-severity-rating-system",
      "text": "Critical"
    },
    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Public",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en-US",
    "notes": [
      {
        "category": "general",
        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
      },
      {
        "category": "general",
        "text": "Required. The vulnerability documented by this CVE requires customer action to resolve.",
        "title": "Customer Action"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2021-42298 Microsoft Defender Remote Code Execution Vulnerability - HTML",
        "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42298"
      },
      {
        "category": "self",
        "summary": "CVE-2021-42298 Microsoft Defender Remote Code Execution Vulnerability - CSAF",
        "url": "https://msrc.microsoft.com/csaf/advisories/2021/msrc_cve-2021-42298.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Exploitability Index",
        "url": "https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1"
      },
      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
        "url": "https://support.microsoft.com/lifecycle"
      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "Microsoft Defender Remote Code Execution Vulnerability",
    "tracking": {
      "current_release_date": "2021-11-09T08:00:00.000Z",
      "generator": {
        "date": "2026-01-06T16:30:40.827Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2021-42298",
      "initial_release_date": "2021-11-09T08:00:00.000Z",
      "revision_history": [
        {
          "date": "2021-11-09T08:00:00.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "1"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "category": "product_version_range",
            "name": "\u003c1.1.18700.3",
            "product": {
              "name": "Microsoft Malware Protection Engine \u003c1.1.18700.3",
              "product_id": "1"
            }
          },
          {
            "category": "product_version",
            "name": "1.1.18700.3",
            "product": {
              "name": "Microsoft Malware Protection Engine 1.1.18700.3",
              "product_id": "11902"
            }
          }
        ],
        "category": "product_name",
        "name": "Microsoft Malware Protection Engine"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2021-42298",
      "notes": [
        {
          "category": "general",
          "text": "Microsoft",
          "title": "Assigning CNA"
        },
        {
          "category": "faq",
          "text": "First version of the Microsoft Malware Protection Engine with this vulnerability addressed: First version of the Microsoft Malware Protection Engine with this vulnerability addressed, Version  1.1.18700.3: Version  1.1.18700.3\nSee Manage Updates Baselines Microsoft Defender Antivirus for more information.\nVulnerability scanners are looking for specific binaries and version numbers on devices. Microsoft Defender files are still on disk even when disabled. Systems that have disabled Microsoft Defender are not in an exploitable state.\nIn response to a constantly changing threat landscape, Microsoft frequently updates malware definitions and the Microsoft Malware Protection Engine. In order to be effective in helping protect against new and prevalent threats, antimalware software must be kept up to date with these updates in a timely manner.\nFor enterprise deployments as well as end users, the default configuration in Microsoft antimalware software helps ensure that malware definitions and the Microsoft Malware Protection Engine are kept up to date automatically. Product documentation also recommends that products are configured for automatic updating.\nBest practices recommend that customers regularly verify whether software distribution, such as the automatic deployment of Microsoft Malware Protection Engine updates and malware definitions, is working as expected in their environment.\nMicrosoft typically releases an update for the Microsoft Malware Protection Engine once a month or as needed to protect against new threats. Microsoft also typically updates the malware definitions three times daily and can increase the frequency when needed.\nDepending on which Microsoft antimalware software is used and how it is configured, the software may search for engine and definition updates every day when connected to the Internet, up to multiple times daily. Customers can also choose to manually check for updates at any time.\nThe Microsoft Malware Protection Engine, mpengine.dll, provides the scanning, detection, and cleaning capabilities for Microsoft antivirus and antispyware software.\nDefender runs on all supported version of Windows.\nYes, Microsoft System Center Endpoint Protection, Microsoft System Center 2012 R2 Endpoint Protection, Microsoft System Center 2012 Endpoint Protection and Microsoft Security Essentials.\nYes.\u00a0 In addition to the changes that are listed for this vulnerability, this update includes defense-in-depth updates to help improve security-related features.\nCustomers should verify that the latest version of the Microsoft Malware Protection Engine and definition updates are being actively downloaded and installed for their Microsoft antimalware products.\nOpen the Windows Security program. For example, type Security in the Search bar, and select the Windows Security program.\nIn the navigation pane, select Virus \u0026amp; threat protection.\nUnder Virus \u0026amp; threat protection updates in the main window, select Check for updates\nSelect Check for updates again.\nIn the navigation pane, select Settings, and then select About.\nExamine the Engine Version number. The update was successfully installed if the Malware Protection Engine version number or the signature package version number matches or exceeds the version number that you are trying to verify as installed.\nFor affected software, verify that the Microsoft Malware Protection Engine version is 1.1.18700.3 or later.\nAdministrators of enterprise antimalware deployments should ensure that their update management software is configured to automatically approve and distribute engine updates and new malware definitions. Enterprise administrators should also verify that the latest version of the Microsoft Malware Protection Engine and definition updates are being actively downloaded, approved and deployed in their environment.\nFor end-users, the affected software provides built-in mechanisms for the automatic detection and deployment of this update. For these customers, the update will be applied within 48 hours of its availability. The exact time frame depends on the software used, Internet connection, and infrastructure configuration.\nEnd users that do not wish to wait can manually update their antimalware software.",
          "title": "Microsoft Defender is disabled in my environment, why are vulnerability scanners showing that I am vulnerable to this issue?"
        }
      ],
      "product_status": {
        "fixed": [
          "11902"
        ],
        "known_affected": [
          "1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2021-42298 Microsoft Defender Remote Code Execution Vulnerability - HTML",
          "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42298"
        },
        {
          "category": "self",
          "summary": "CVE-2021-42298 Microsoft Defender Remote Code Execution Vulnerability - CSAF",
          "url": "https://msrc.microsoft.com/csaf/advisories/2021/msrc_cve-2021-42298.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2021-11-09T08:00:00.000Z",
          "details": "1.1.18700.3:Security Update:https://docs.microsoft.com/en-us/microsoft-365/security/defender-endpoint/manage-updates-baselines-microsoft-defender-antivirus?view=o365-worldwide",
          "product_ids": [
            "1"
          ],
          "url": "https://docs.microsoft.com/en-us/microsoft-365/security/defender-endpoint/manage-updates-baselines-microsoft-defender-antivirus?view=o365-worldwide"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "environmentalsScore": 0.0,
            "exploitCodeMaturity": "UNPROVEN",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "remediationLevel": "OFFICIAL_FIX",
            "reportConfidence": "CONFIRMED",
            "scope": "UNCHANGED",
            "temporalScore": 6.8,
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C",
            "version": "3.1"
          },
          "products": [
            "1"
          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Remote Code Execution"
        },
        {
          "category": "exploit_status",
          "details": "Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation More Likely;Older Software Release:Exploitation More Likely"
        }
      ],
      "title": "Microsoft Defender Remote Code Execution Vulnerability"
    }
  ]
}