CVE-2019-17190

{
  "id": "CVE-2019-17190",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 7.2,
          "accessVector": "LOCAL",
          "vectorString": "AV:L/AC:L/Au:N/C:C/I:C/A:C",
          "authentication": "NONE",
          "integrityImpact": "COMPLETE",
          "accessComplexity": "LOW",
          "availabilityImpact": "COMPLETE",
          "confidentialityImpact": "COMPLETE"
        },
        "acInsufInfo": false,
        "impactScore": 10,
        "baseSeverity": "HIGH",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 3.9,
        "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
      }
    ]
  },
  "affected": [
    {
      "source": "cve@mitre.org",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ]
    }
  ],
  "published": "2020-01-27T16:15:11.220",
  "references": [
    {
      "url": "http://packetstormsecurity.com/files/156844/Avast-Secure-Browser-76.0.1659.101-Local-Privilege-Escalation.html",
      "tags": [
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "http://seclists.org/fulldisclosure/2020/Mar/25",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://www.avast.com/bug-bounty-credits/en/a-tribute-to-our-security-research-community",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "http://packetstormsecurity.com/files/156844/Avast-Secure-Browser-76.0.1659.101-Local-Privilege-Escalation.html",
      "tags": [
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://seclists.org/fulldisclosure/2020/Mar/25",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.avast.com/bug-bounty-credits/en/a-tribute-to-our-security-research-community",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-863"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "A Local Privilege Escalation issue was discovered in Avast Secure Browser 76.0.1659.101. The vulnerability is due to an insecure ACL set by the AvastBrowserUpdate.exe (which is running as NT AUTHORITY\\SYSTEM) when AvastSecureBrowser.exe checks for new updates. When the update check is triggered, the elevated process cleans the ACL of the Update.ini file in %PROGRAMDATA%\\Avast Software\\Browser\\Update\\ and sets all privileges to group Everyone. Because any low-privileged user can create, delete, or modify the Update.ini file stored in this location, an attacker with low privileges can create a hard link named Update.ini in this folder, and make it point to a file writable by NT AUTHORITY\\SYSTEM. Once AvastBrowserUpdate.exe is triggered by the update check functionality, the DACL is set to a misconfigured value on the crafted Update.ini and, consequently, to the target file that was previously not writable by the low-privileged attacker."
    },
    {
      "lang": "es",
      "value": "Se detectó un problema de Escalada de Privilegios Local en Avast Secure Browser versión 76.0.1659.101. La vulnerabilidad es debido a una ACL no segura establecida por el archivo AvastBrowserUpdate.exe (que se ejecuta como la cuenta NT AUTHORITY\\SYSTEM) cuando el archivo AvastSecureBrowser.exe busca nuevas actualizaciones. Cuando la comprobación de actualización es activada, el proceso elevado limpia la ACL del archivo Update.ini en %PROGRAMDATA%\\Avast Software\\Browser\\Update\\ y establece todos los privilegios para el grupo Everyone. Debido a que cualquier usuario con poco privilegiado puede crear, eliminar o modificar el archivo Update.ini almacenado en esta ubicación, un atacante con pocos privilegios puede crear un enlace físico llamado Update.ini en esta carpeta y hacer que apunte hacia un archivo escribible por la cuenta NT AUTHORITY\\SYSTEM. Una vez que el archivo AvastBrowserUpdate.exe es activado por la funcionalidad de comprobación de actualización, la DACL es establecida en un valor mal configurado en el archivo Update.ini diseñado y, en consecuencia, en el archivo de destino que previamente no era escribible por parte de un usuario poco privilegiado"
    }
  ],
  "lastModified": "2026-06-17T02:23:26.663",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:avast:secure_browser:76.0.1659.101:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "C71BBFA5-0BAF-4897-BF47-F282ED240060"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve@mitre.org"
}