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CVE-2020-8903

Estado: ModificadaAlta (7.3)—

A vulnerability in Google Cloud Platform's guest-oslogin versions between 20190304 and 20200507 allows a user that is only granted the role "roles/compute.osLogin" to escalate privileges to root. Using their membership to the "adm" group, users with this role are able to read the DHCP XID from the systemd journal. Using the DHCP XID, it is then possible to set the IP address and hostname of the instance to any value, which is then stored in /etc/hosts.

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An attacker can then point metadata.google.internal to an arbitrary IP address and impersonate the GCE metadata server which make it is possible to instruct the OS Login PAM module to grant administrative privileges. All images created after 2020-May-07 (20200507) are fixed, and if you cannot update, we recommend you edit /etc/group/security.conf and remove the "adm" user from the OS Login entry.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (2)

Google — Guest-osloginOpensuse — Leap

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2020-8903",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 6.9,
          "accessVector": "LOCAL",
          "vectorString": "AV:L/AC:M/Au:N/C:C/I:C/A:C",
          "authentication": "NONE",
          "integrityImpact": "COMPLETE",
          "accessComplexity": "MEDIUM",
          "availabilityImpact": "COMPLETE",
          "confidentialityImpact": "COMPLETE"
        },
        "acInsufInfo": false,
        "impactScore": 10,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 3.4,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      }
    ],
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "cve-coordination@google.com",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 7.3,
          "Automatable": "NOT_DEFINED",
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "exploitMaturity": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "ACTIVE",
          "attackComplexity": "HIGH",
          "attackRequirements": "NONE",
          "privilegesRequired": "LOW",
          "subIntegrityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "HIGH",
          "vulnAvailabilityImpact": "HIGH",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "HIGH",
          "vulnConfidentialityImpact": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
        }
      }
    ]
  },
  "affected": [
    {
      "source": "cve-coordination@google.com",
      "affectedData": [
        {
          "vendor": "Google LLC",
          "product": "guest-oslogin",
          "versions": [
            {
              "status": "affected",
              "version": "20190304",
              "lessThan": "20200507",
              "versionType": "date"
            },
            {
              "status": "unaffected",
              "version": "20200507",
              "versionType": "date"
            }
          ],
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2020-06-22T14:15:11.643",
  "references": [
    {
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00037.html",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "cve-coordination@google.com"
    },
    {
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00047.html",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "cve-coordination@google.com"
    },
    {
      "url": "https://cloud.google.com/support/bulletins/#gcp-2020-008",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "cve-coordination@google.com"
    },
    {
      "url": "https://github.com/GoogleCloudPlatform/guest-oslogin/pull/29",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "cve-coordination@google.com"
    },
    {
      "url": "https://gitlab.com/gitlab-com/gl-security/gl-redteam/red-team-tech-notes/-/tree/master/oslogin-privesc-june-2020",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "cve-coordination@google.com"
    },
    {
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00037.html",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00047.html",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://cloud.google.com/support/bulletins/#gcp-2020-008",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://github.com/GoogleCloudPlatform/guest-oslogin/pull/29",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://gitlab.com/gitlab-com/gl-security/gl-redteam/red-team-tech-notes/-/tree/master/oslogin-privesc-june-2020",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "cve-coordination@google.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-276"
        }
      ]
    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-276"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "A vulnerability in Google Cloud Platform's guest-oslogin versions between 20190304 and 20200507 allows a user that is only granted the role \"roles/compute.osLogin\" to escalate privileges to root. Using their membership to the \"adm\" group, users with this role are able to read the DHCP XID from the systemd journal. Using the DHCP XID, it is then possible to set the IP address and hostname of the instance to any value, which is then stored in /etc/hosts. An attacker can then point metadata.google.internal to an arbitrary IP address and impersonate the GCE metadata server which make it is possible to instruct the OS Login PAM module to grant administrative privileges. All images created after 2020-May-07 (20200507) are fixed, and if you cannot update, we recommend you edit /etc/group/security.conf and remove the \"adm\" user from the OS Login entry."
    },
    {
      "lang": "es",
      "value": "Una vulnerabilidad en las versiones entre 20190304 y 20200507 de guest-oslogin de Google Cloud Platform, permite a un usuario al que solo se le otorga el rol \"roles/compute.osLogin\" para escalar privilegios a root. Al usar su membresía en el grupo \"adm\", los usuarios con este rol son capaces de leer el XID de DHCP desde el diario systemd. Con el XID de DHCP, es posible configurar la dirección IP y el nombre de host de la instancia en cualquier valor, que luego es almacenada en /etc/hosts. Un atacante puede luego apuntar a metadata.google.internal en una dirección IP arbitraria y suplantar al servidor de metadatos GCE que hace posible que el módulo PAM de inicio de sesión del Sistema Operativo otorgue privilegios administrativos. Todas las imágenes creadas  después del 07 de mayo 2020 (20200507) están corregidas, y si no puede actualizar, le recomendamos editar /etc/group/security.conf y eliminar el usuario \"adm\" de la entrada de inicio de sesión del sistema operativo"
    }
  ],
  "lastModified": "2026-06-17T03:27:09.223",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:google:guest-oslogin:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "9751996A-374C-4002-A06F-CA2B0A5D7609",
              "versionEndIncluding": "20200507.00",
              "versionStartIncluding": "20190304.00"
            }
          ],
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "B620311B-34A3-48A6-82DF-6F078D7A4493"
            },
            {
              "criteria": "cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "B009C22E-30A4-4288-BCF6-C3E81DEAF45A"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve-coordination@google.com"
}