+3.2.5 Phishing Resistance
---+3.2.5.1 Channel Binding
---+3.2.5.2 Verifier Name Binding

3.2.5 Phishing Resistance

Phishing attacks, previously referred to in SP 800-63B as “verifier impersonation,” are attempts by fraudulent verifiers and RPs to fool an unwary claimant into presenting an authenticator to an impostor. In some prior versions of SP 800-63, protocols that are resistant to phishing attacks were also referred to as “strongly MitM-resistant.”

In this document, phishing resistance is the ability of the authentication protocol to prevent the disclosure of authentication secrets and valid authenticator outputs to an impostor verifier (i.e., an attacker fraudulently posing as the verifier) without relying on the vigilance of the claimant. How the claimant is directed to the impostor verifier is not relevant. For example, regardless of whether the claimant was directed there via search engine optimization or prompted by email, it is considered to be a phishing attack.

Approved cryptographic algorithms SHALL be used to establish phishing resistance where required. Keys used for this purpose SHALL provide at least the minimum security strength specified in the latest revision of [SP800-131A] (i.e., 112 bits as of the date of this publication).

Phishing resistance requires single- or multi-factor cryptographic authentication. Authenticators that involve the manual entry of an authenticator output (e.g., out-of-band and OTP authenticators) SHALL NOT be considered phishing-resistant because the manual entry does not bind the authenticator output to the specific session being authenticated. For example, an impostor verifier could relay an authenticator output to the verifier and successfully authenticate.

Two methods of phishing resistance are recognized: channel binding and verifier name binding. Channel binding is considered more secure than verifier name binding because it is not vulnerable to the misissuance or misappropriation of verifier certificates, but both methods satisfy the requirements for phishing resistance.

1. Übersicht

Bezeichnung Standard
3.2.5.1 Channel Binding

An authentication protocol with channel binding SHALL establish an authenticated protected channel with the verifier. The protocol SHALL then strongly and irreversibly bind a channel identifier negotiated in establishing the authenticated protected channel to the authenticator output (e.g., by signing the two values together using a private key controlled by the claimant for which the public key is known to the verifier). The verifier SHALL validate the signature or other information used to prove phishing resistance. This prevents an impostor verifier — even one that has obtained a certificate that represents the actual verifier — from successfully relaying that authentication on a different authenticated protected channel.

An example of a phishing-resistant authentication protocol that uses channel binding is client-authenticated TLS [RFC8446] in which the client signs the authenticator output along with earlier messages from the protocol that are unique to the particular TLS connection being negotiated. Personal identity verification (PIV) and common access card (CAC) cards, which use client-authenticated TLS, provide phishing resistance through channel binding.

3.2.5.2 Verifier Name Binding

An authentication protocol with verifier name binding SHALL establish an authenticated protected channel with the verifier. The protocol SHALL then generate an authenticator output that is cryptographically bound to a verifier identifier that is authenticated as part of the protocol. In the case of DNS identifiers, the verifier identifier SHALL be either the authenticated hostname of the verifier or a parent domain that is at least one level below the public suffix [PSL] associated with that hostname. The binding MAY be established by choosing an associated authenticator secret, deriving an authenticator secret using the verifier identifier, cryptographically signing the authenticator output with the verifier identifier, or using similar cryptographically secure means.

WebAuthn [WebAuthn], which is used by authenticators that implement the Fast Identity Online 2 (FIDO2) specifications [FIDO2], is an example of a standard that provides phishing resistance through verifier name binding by choosing an authenticator secret based on the authenticated domain name of the verifier.

1.1 Referenzen

1.2 Identifizierte Anforderungen

1.3 Zugehörige Regulierungen

2. Identifizierte Anforderungen

Anforderungen
Quelle Anforderung

3. Zugehörige Regulierungen

Regulierungen
Quelle Regulierung
  • NIST -

    EN: Publications of the National Institute of Standards and Technology (NIST), U.S. Department of Commerce, https://www.nist.gov/, from their electronic versions (OSCAL; SP 800-63-4 from its HTML version, https://pages.nist.gov/800-63-4/). Works of NIST employees are not subject to copyright protection in the United States (17 U.S.C. § 105); the OSCAL content is dedicated to the public domain worldwide (CC0 1.0); outside the United States NIST grants the right to reprint its technical series publications in all formats (NIST copyright statement). Republished courtesy of the National Institute of Standards and Technology; each document names its citation. Divided into sections and converted into the GRCA format, the wording unchanged. Only the versions published by NIST are authoritative.

    DE: Veröffentlichungen des National Institute of Standards and Technology (NIST), U.S. Department of Commerce, https://www.nist.gov/, aus ihren elektronischen Fassungen (OSCAL; SP 800-63-4 aus ihrer HTML-Fassung, https://pages.nist.gov/800-63-4/). Werke von NIST-Beschäftigten sind in den USA urheberrechtlich nicht geschützt (17 U.S.C. § 105); die OSCAL-Inhalte sind weltweit gemeinfrei gestellt (CC0 1.0); außerhalb der USA räumt das NIST das Recht ein, seine Technical-Series-Publikationen in allen Formaten neu zu veröffentlichen (Copyright-Hinweis des NIST). „Republished courtesy of the National Institute of Standards and Technology“; jedes Dokument nennt seine Zitierangabe. In Abschnitte aufgeteilt und in das GRCA-Format umgewandelt, der Wortlaut unverändert. Maßgeblich sind allein die vom NIST veröffentlichten Fassungen.