GHSA-875X-G8P7-5W27

Vulnerability from github – Published: 2024-07-15 16:37 – Updated: 2024-07-15 21:38
VLAI?
Summary
The FIDO2/Webauthn Support for PHP library allows enumeration of valid usernames
Details

Summary

The ProfileBasedRequestOptionsBuilder method returns allowedCredentials without any credentials if no username was found.

Details

When WebAuthn is used as the first or only authentication method, an attacker can enumerate usernames based on the absence of the allowedCredentials property in the assertion options response. This allows enumeration of valid or invalid usernames.

Proposal how to resolve it:

return $this->publicKeyCredentialRequestOptionsFactory->create(
            $this->profile,
            count($allowedCredentials) <= 0 ? self::getRandomCredentials(): $allowedCredentials,
            $optionsRequest->userVerification,
            $extensions
);

private static function getRandomCredentials(): array
{
        $credentialSources = [];
        for ($i = 0; $i <= rand(0,1); $i++) {
            $credentialSources[] = new PublicKeyCredentialSource(
                random_bytes(32),
                "public-key",
                [],
                "basic",
                new EmptyTrustPath(),
                Uuid::v7(),
                random_bytes(77),
                Uuid::v7()->__toString(),
                rand(0, 6000),
                null
            );
        }
        return array_map(
            static fn (PublicKeyCredentialSource $credential): PublicKeyCredentialDescriptor => $credential->getPublicKeyCredentialDescriptor(),
            $credentialSources
        );
}

PoC

curl https://example.com/assertion/options \ -H 'content-type: application/json' \ --data-raw '{"username":"NotMeRandomUsername123"}'

Impact

By knowing which usernames are valid, attackers can focus their efforts on a smaller set of potential targets, increasing the efficiency and likelihood of successful attacks.

Severity ?
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "web-auth/webauthn-lib"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.5.0"
            },
            {
              "fixed": "4.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "web-auth/webauthn-framework"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.5.0"
            },
            {
              "fixed": "4.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-39912"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-204"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-07-15T16:37:49Z",
    "nvd_published_at": "2024-07-15T20:15:03Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nThe ProfileBasedRequestOptionsBuilder method returns allowedCredentials without any credentials if no username was found.\n\n### Details\n\nWhen WebAuthn is used as the first or only authentication method, an attacker can enumerate usernames based on the absence of the `allowedCredentials` property in the assertion options response. This allows enumeration of valid or invalid usernames.\n\n#### Proposal how to resolve it:\n \n```\nreturn $this-\u003epublicKeyCredentialRequestOptionsFactory-\u003ecreate(\n            $this-\u003eprofile,\n            count($allowedCredentials) \u003c= 0 ? self::getRandomCredentials(): $allowedCredentials,\n            $optionsRequest-\u003euserVerification,\n            $extensions\n);\n\nprivate static function getRandomCredentials(): array\n{\n        $credentialSources = [];\n        for ($i = 0; $i \u003c= rand(0,1); $i++) {\n            $credentialSources[] = new PublicKeyCredentialSource(\n                random_bytes(32),\n                \"public-key\",\n                [],\n                \"basic\",\n                new EmptyTrustPath(),\n                Uuid::v7(),\n                random_bytes(77),\n                Uuid::v7()-\u003e__toString(),\n                rand(0, 6000),\n                null\n            );\n        }\n        return array_map(\n            static fn (PublicKeyCredentialSource $credential): PublicKeyCredentialDescriptor =\u003e $credential-\u003egetPublicKeyCredentialDescriptor(),\n            $credentialSources\n        );\n}\n```\n\n### PoC\n\ncurl https://example.com/assertion/options \\\n  -H \u0027content-type: application/json\u0027 \\\n  --data-raw \u0027{\"username\":\"NotMeRandomUsername123\"}\u0027\n\n### Impact\n\nBy knowing which usernames are valid, attackers can focus their efforts on a smaller set of potential targets, increasing the efficiency and likelihood of successful attacks.\n",
  "id": "GHSA-875x-g8p7-5w27",
  "modified": "2024-07-15T21:38:21Z",
  "published": "2024-07-15T16:37:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/web-auth/webauthn-framework/security/advisories/GHSA-875x-g8p7-5w27"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-39912"
    },
    {
      "type": "WEB",
      "url": "https://github.com/web-auth/webauthn-framework/commit/64de11f6cddc71e56c76e0cc4573bf94d02be045"
    },
    {
      "type": "WEB",
      "url": "https://github.com/web-auth/webauthn-framework/commit/a9d1352897fba552e659e1445a771dec2d4ed05a"
    },
    {
      "type": "WEB",
      "url": "https://github.com/web-auth/webauthn-lib/commit/b6798de27cdedd8681fe4c9b13ace0ff2456d18b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/web-auth/webauthn-framework"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "The FIDO2/Webauthn Support for PHP library allows enumeration of valid usernames "
}


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