From 5b346313f1cecd3c4c79b6e104094e50bb1cfa75 Mon Sep 17 00:00:00 2001 From: Jacob Champion Date: Mon, 22 May 2023 16:46:23 -0700 Subject: [PATCH] docs: encourage strong server verification with SCRAM The server verification in libpq's SCRAM implementation can be subverted in various ways. While mitigations for some of the issues exist, it's probably wise for most users to combine it with strong server authentication, to avoid entering a SCRAM exchange with an untrusted server. Recommend that in the docs. --- doc/src/sgml/runtime.sgml | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml index dbe23db54f..cf93d9443c 100644 --- a/doc/src/sgml/runtime.sgml +++ b/doc/src/sgml/runtime.sgml @@ -2021,6 +2021,21 @@ pg_dumpall -p 5432 | psql -d postgres -p 5433 authentication with them. The TCP client must connect using gssencmode=require. + + + + While the SCRAM authentication method () + theoretically provides a form of server authentication without the use of + certificates, the current SCRAM implementation does not protect the entire + authentication exchange. A spoofed server (or an active attacker on the + network) may tamper with the startup packet or attempt to bypass the + client's server verification step. Additionally, an attacker on the wire + may use an intercepted SCRAM exchange to begin a brute-force attack + against the password offline. It's recommended to employ strong server + authentication, using one of the above anti-spoofing measures, to prevent + these attacks. + + -- 2.25.1