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Merge pull request #2588 from drwetter/fix_2582

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Mute socat killing & improve STARTTLS grading explanation
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Dirk Wetter 2024-10-15 12:26:35 +02:00 committed by GitHub
commit b2e6f990b9
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1 changed files with 7 additions and 4 deletions
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testssl.sh
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@ -19322,7 +19322,7 @@ run_starttls_injection() {
esac
uds="$TEMPDIR/uds"
$SOCAT FD:5 UNIX-LISTEN:$uds &
$SOCAT FD:5 UNIX-LISTEN:$uds 2>/dev/null &
socat_pid=$!
if "$HAS_UDS"; then
@ -22934,11 +22934,11 @@ run_rating() {
pr_headlineln " Rating (experimental) "
outln
[[ -n "$STARTTLS_PROTOCOL" ]] && set_grade_cap "T" "STARTTLS is prone to MITM downgrade attacks. A secure TLS upgrade can only be ensured client-side. You should use TLS only (=implicit TLS) rather than STARTTLS as per RFC 8314, for other than SMTP and SIEVE"
[[ -n "$STARTTLS_PROTOCOL" ]] && set_grade_cap "T" "STARTTLS is prone to MITM downgrade attacks. A secure TLS upgrade can only be ensured client-side. As per RFC 8314 you should use implicit TLS rather than STARTTLS. For SMTP (port 25) and SIEVE this is not possible."
# TL;DR: STARTTLS connections are inherently insecure. A MITM can always intercept the connection, unless the client checks e.g. the
# certificate accordingly. A secure STARTTLS client is the key but we can't test for it. For other than SMTP and SIEVE (there's no implicit TLS port)
# you should use implicit TLS as per RFC 8314. Especially e-mail transfer via port 25 is broken and amendments so far are duct tape.
# certificate accordingly. A secure STARTTLS client is the key but we can't test for it. Especially e-mail transfer via port 25 is broken
# as message delivery is still more important than security. Amendments like DANE and MTA-STS are duct tape and depend on the client.
# Explanation: There are active MitM attacks possible when using STARTTLS like https://github.com/tintinweb/striptls or
# https://github.com/libcrack/starttlsstrip. It depends on the client only whether it can detect such downgrade attack.
@ -22946,6 +22946,9 @@ run_rating() {
# accept those wrong certificates -- delivering e-mails is more important. There is an e-mail submission port 587 but a mail server
# cannot just switch to it and continue to receive mail from everyone. Even if you advertise this via SRV record (RFC 6186).
# TLSA Records/DANE and MTA-STS (RFC-8461) on the server side can help too,
#
# For other than SMTP on port 25 and port 587 and SIEVE (there's no implicit TLS port) you should use implicit TLS as per RFC 8314.
# Instead of port 587 (STARTTLS) implicit TLS on port 465 should be considered.
pr_bold " Rating specs"; out " (not complete) "; outln "SSL Labs's 'SSL Server Rating Guide' (version 2009q from 2020-01-30)"
pr_bold " Specification documentation "; pr_url "https://github.com/ssllabs/research/wiki/SSL-Server-Rating-Guide"