From 3b2939febdeb7f92051f95a3b08cf86e221ce21d Mon Sep 17 00:00:00 2001 From: Guilhem Moulin Date: Mon, 3 Aug 2020 20:27:38 +0200 Subject: libinterimap: abort on PREAUTH greeting received on plaintext connections Set "STARTTLS = NO" to ignore. This is similar to CVE-2020-12398 and CVE-2020-14093. --- tests/preauth-plaintext/imapd | 44 ++++++++++++++++++++++++++++++++ tests/preauth-plaintext/interimap.remote | 1 + tests/preauth-plaintext/t | 19 ++++++++++++++ 3 files changed, 64 insertions(+) create mode 100755 tests/preauth-plaintext/imapd create mode 120000 tests/preauth-plaintext/interimap.remote create mode 100644 tests/preauth-plaintext/t (limited to 'tests/preauth-plaintext') diff --git a/tests/preauth-plaintext/imapd b/tests/preauth-plaintext/imapd new file mode 100755 index 0000000..8f3ac30 --- /dev/null +++ b/tests/preauth-plaintext/imapd @@ -0,0 +1,44 @@ +#!/usr/bin/perl -T + +use warnings; +use strict; + +use Errno qw/EINTR/; +use Socket qw/INADDR_LOOPBACK AF_INET SOCK_STREAM pack_sockaddr_in + SOL_SOCKET SO_REUSEADDR SHUT_RDWR/; + +socket(my $S, AF_INET, SOCK_STREAM, 0) or die; +setsockopt($S, SOL_SOCKET, SO_REUSEADDR, pack("l", 1)) or die; +bind($S, pack_sockaddr_in(10143, INADDR_LOOPBACK)) or die "bind: $!\n"; +listen($S, 1) or die "listen: $!"; + +while (1) { + my $sockaddr = accept(my $conn, $S) or do { + next if $! == EINTR; + die "accept: $!"; + }; + + # minimum CAPABILITY list, see tests/snippets/dovecot/interimap-required-capabilities.conf + $conn->printflush("* PREAUTH [CAPABILITY IMAP4rev1 ENABLE UIDPLUS LIST-EXTENDED QRESYNC LIST-STATUS] IMAP4rev1 Server\r\n"); + my $x; + + $x = $conn->getline() // next; + $x =~ /\A(\S+) ENABLE QRESYNC\r\n/ or die; + $conn->printflush("* ENABLED QRESYNC\r\n$1 OK ENABLE completed\r\n"); + + $x = $conn->getline() // next; + $x =~ /\A(\S+) LIST .*\r\n/ or die; + $conn->print("* LIST (\\Noselect) \"~\" \"\"\r\n"); + $conn->print("* LIST () \"~\" INBOX\r\n"); + $conn->print("* STATUS INBOX (UIDNEXT 1 UIDVALIDITY 1 HIGHESTMODSEQ 1)\r\n"); + $conn->printflush("$1 OK LIST completed\r\n"); + + close($conn); +} + +END { + if (defined $S) { + shutdown($S, SHUT_RDWR) or warn "shutdown: $!"; + close($S) or print STDERR "Can't close: $!\n"; + } +} diff --git a/tests/preauth-plaintext/interimap.remote b/tests/preauth-plaintext/interimap.remote new file mode 120000 index 0000000..ad49677 --- /dev/null +++ b/tests/preauth-plaintext/interimap.remote @@ -0,0 +1 @@ +../starttls/interimap.remote \ No newline at end of file diff --git a/tests/preauth-plaintext/t b/tests/preauth-plaintext/t new file mode 100644 index 0000000..427d57b --- /dev/null +++ b/tests/preauth-plaintext/t @@ -0,0 +1,19 @@ +# Test IMAP MiTM via PREAUTH greeting +# For background see CVE-2020-12398, CVE-2020-14093 and +# https://gitlab.com/muttmua/mutt/commit/3e88866dc60b5fa6aaba6fd7c1710c12c1c3cd01 + +env -i USER="remote" HOME="$HOME_remote" "$TESTDIR/imapd" & PID=$! +trap "ptree_abort $PID" EXIT INT TERM + +! interimap --debug || error +grep -Fx 'remote: ERROR: PREAUTH greeting on plaintext connection? MiTM in action? Aborting, set "STARTTLS = NO" to ignore.' <"$STDERR" || error +! grep '^remote: C: ' <"$STDERR" || error "wrote command in MiTM'ed PREAUTH connection!" + + +# Ignore the warning when STARTTLS is explicitely disabled +echo "STARTTLS = NO" >>"$XDG_CONFIG_HOME/interimap/config" +interimap --debug || true + +grep -Fx "remote: S: * STATUS INBOX (UIDNEXT 1 UIDVALIDITY 1 HIGHESTMODSEQ 1)" <"$STDERR" || error + +# vim: set filetype=sh : -- cgit v1.2.3