Git/testssl.sh
1
0
Fork 0
mirror of https://github.com/drwetter/testssl.sh.git synced 2026-02-01 10:45:12 +01:00
Code Issues Packages Projects Releases Wiki Activity

Flag absence of extended master secret extension

Browse Source 
This PR fixes #2806 and implements a feature request. TLS >=1.2 MUST support
support the extended_master_secret extension to address an attack resulting
from TLS session parameters not being properly authenticated in a Triple
Handshake scanario (https://ieeexplore.ieee.org/document/6956559).

Only if the extension is missing there will be a medium severity level
finding. JSON output will be generated in any case.

Also in determine_tls_extensions() some documenation about tls extensions
to be send were added.
This commit is contained in:
Dirk
2026-01-14 20:22:59 +01:00
parent 251d5ac02a
commit 52ffa95696
1 changed files with 32 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

33
testssl.sh
View File

@@ -8223,6 +8223,12 @@ determine_tls_extensions() {
"$SSL_NATIVE" && using_sockets=false
if "$using_sockets"; then
# 01 max_fragment_length, RFC 6066
# 02 client_certificate_url, RFC 6066
# 04 truncated_hmac, RFC 6066
# signed_certificate_timestamp, RFC 6962
# encrypt_then_mac, RFC 7366
# extended_master_secret, RFC 7627
tls_extensions="00,01,00,01,02, 00,02,00,00, 00,04,00,00, 00,12,00,00, 00,16,00,00, 00,17,00,00"
if [[ -z $STARTTLS ]]; then
for alpn_proto in $ALPN_PROTOs; do
@@ -10407,6 +10413,7 @@ certificate_info() {
return $ret
}
run_server_defaults() {
local ciph newhostcert sni
local match_found
@@ -10421,6 +10428,7 @@ run_server_defaults() {
local -a -i success
local cn_nosni cn_sni sans_nosni sans_sni san tls_extensions extn client_auth_ca
local using_sockets=true
local spaces=" "
"$SSL_NATIVE" && using_sockets=false
@@ -10677,7 +10685,7 @@ run_server_defaults() {
pr_headlineln " Testing server defaults (Server Hello) "
outln
pr_bold " TLS extensions (standard) "
pr_bold " TLS extensions "
if [[ ${#TLS_EXTENSIONS[*]} -eq 0 ]]; then
outln "(none)"
fileout "TLS_extensions" "INFO" "(none)"
@@ -10702,6 +10710,28 @@ run_server_defaults() {
outln "$tls_extensions"
fi
# We want to check whether the (for >=TLS 1.2) mandatory "extended master secret" extension is supported by
# the server. Otherwise it would violate RFC 9325 https://www.rfc-editor.org/rfc/rfc9325#section-3.5
# and cause connection problems.
jsonID="TLS_misses_extension_23"
if [[ $(has_server_protocol "tls1_2") -eq 1 ]] && [[ $(has_server_protocol "tls1_3") -eq 1 ]] ; then
:
elif [[ $tls_extensions =~ \#23 ]]; then
# Was the last handshake >= TLS 1.2 ?
if grep -qE 'Protocol.*(TLSv1.3|TLSv1.2)' $TEMPDIR/$NODEIP.parse_tls_serverhello.txt ; then
fileout "$jsonID" "INFO" "Extended master secret extension detected"
debugme outln "${spaces}Extended master secret extension detected"
else
out "$spaces"
prln_warning "Fixme: Server supports TLS 1.2 or 1.3 but last ServerHello was < TLS 1.2"
fileout "$jsonID" "WARN" "Server supports TLS 1.2 or 1.3 but last ServerHello was < TLS 1.2"
fi
else
out "$spaces"
prln_svrty_medium "No extended master secret extension, violates RFC 9325 & may cause connection problems"
fileout "$jsonID" "MEDIUM" "No extended master secret extension, violates RFC 9325 & may cause connection problems"
fi
pr_bold " Session Ticket RFC 5077 hint "
jsonID="TLS_session_ticket"
if [[ -z "$sessticket_lifetime_hint" ]]; then
@@ -10923,6 +10953,7 @@ run_server_defaults() {
return $ret
}
get_session_ticket_lifetime_from_serverhello() {
awk '/session ticket.*lifetime/ { print $(NF-1) "$1" }'
}