Re: [quicwg/base-drafts] Import HTTP/2 Security Considerations (#3531)

Mike Bishop <> Thu, 19 March 2020 12:42 UTC

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Date: Thu, 19 Mar 2020 05:42:31 -0700
From: Mike Bishop <>
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Subject: Re: [quicwg/base-drafts] Import HTTP/2 Security Considerations (#3531)
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MikeBishop commented on this pull request.

> +of establishing authority are discussed in Section 11.1 of {{!SEMANTICS}}.
+## Cross-Protocol Attacks
+The use of ALPN in the TLS and QUIC handshakes establishes the target
+application protocol before application-layer bytes are processed.  Because all
+QUIC packets are encrypted, it is difficult for an attacker to control the
+plaintext bytes of an HTTP/3 connection which could be used in a cross-protocol
+attack on a plaintext protocol.
+## Intermediary Encapsulation Attacks
+The HTTP/3 field encoding allows the expression of names that are not valid
+field names in the syntax used by HTTP (Section 4.3 of {{!SEMANTICS}}). Requests
+or responses containing invalid field names MUST be treated as malformed
+({{malformed}).  An intermediary therefore cannot translate an HTTP/3 request or

I don't think this is a new restriction; it's a statement about the ramifications of a compliant implementation.  If you follow the previous MUST NOT, the ramification is that you cannot produce an invalid HTTP/1.1 request from an HTTP/3 request.

> +Pushed responses for which an origin server is not authoritative (see
+{{connection-reuse}}) MUST NOT be used or cached.

If this were pointing to an expanded description of handling pushed responses, I think that would be the right arrangement. This is pointing specifically to a discussion of when a server is authoritative.

> +denial-of-service attack.  Implementations SHOULD track the use of these
+features and set limits on their use.  An endpoint MAY treat activity that is
+suspicious as a connection error ({{errors}) of type H3_EXCESSIVE_LOAD.
+### Limits on Field Section Size
+A large field section ({{request-response}}) can cause an implementation to
+commit a large amount of state.  Header fields that are critical for routing can
+appear toward the end of a header field section, which prevents streaming of the
+header field section to its ultimate destination.  This ordering and other
+reasons, such as ensuring cache correctness, mean that an endpoint might need to
+buffer the entire header field section.  Since there is no hard limit to the
+size of a field section, some endpoints could be forced to commit a large amount
+of available memory for header fields.
+An endpoint can use the SETTINGS_MAX_HEADER_LIST_SIZE ({{settings-parameters}})

Seems to be up-to-date for now, though we might want to change it per #3452.

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