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Detect support for encrypt-then-mac extension

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In some cases, the "TLS extensions" line output for the "--server-defaults" option will not show `"encrypt-then-mac/#22"` even if the server supports this extension. The reason is that a server will only include this extension in the ServerHello message if it supports the extension and the selected cipher is a CBC cipher. So, if `determine_tls_extensions()` connects to the server with a non-CBC cipher, then it will not detect if the server supports the encrypt-then-mac extension.

It is possible that support for the extension will be detected by `get_server_certificate()`, but only if one of the calls to that function results in a CBC cipher being selected and OpenSSL 1.1.0 is being used (as prior versions did not support the encrypt-then-mac extension).

In this PR, if `determine_tls_extensions()` is called and `$TLS_EXTENSIONS` does not already contain `"encrypt-then-mac/#22"`, then an attempt will be made to connect to the server with only CBC ciphers specified in the ClientHello. If the connection is not successful (presumably because the server does not support any CBC ciphers), then a second connection attempt will be made with the "default" ciphers being specified in the ClientHello.

en.wikipedia.org is an example of a server that supports the encrypt-then-mac extension, but for which the support is not currently detected (unless OpenSSL 1.1.0 is used) since in the call to `determine_tls_extension()` a non-CBC cipher is selected.
This commit is contained in:
David Cooper 2017-01-13 12:13:20 -05:00 committed by GitHub
parent 436326a547
commit 91e0da3485
1 changed files with 24 additions and 9 deletions
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33
testssl.sh
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@ -5165,16 +5165,19 @@ sclient_connect_successful() {
# ALPN extensions in the same ServerHello. # ALPN extensions in the same ServerHello.
determine_tls_extensions() { determine_tls_extensions() {
local addcmd local addcmd
local -i success local -i success=1
local line params="" tls_extensions="" local line params="" tls_extensions=""
local alpn_proto alpn="" alpn_list_len_hex alpn_extn_len_hex local alpn_proto alpn="" alpn_list_len_hex alpn_extn_len_hex
local -i alpn_list_len alpn_extn_len local -i alpn_list_len alpn_extn_len
local cbc_cipher_list="ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA256:DH-RSA-AES256-SHA256:DH-DSS-AES256-SHA256:DHE-RSA-AES256-SHA:DHE-DSS-AES256-SHA:DH-RSA-AES256-SHA:DH-DSS-AES256-SHA:ECDHE-RSA-CAMELLIA256-SHA384:ECDHE-ECDSA-CAMELLIA256-SHA384:DHE-RSA-CAMELLIA256-SHA256:DHE-DSS-CAMELLIA256-SHA256:DH-RSA-CAMELLIA256-SHA256:DH-DSS-CAMELLIA256-SHA256:DHE-RSA-CAMELLIA256-SHA:DHE-DSS-CAMELLIA256-SHA:DH-RSA-CAMELLIA256-SHA:DH-DSS-CAMELLIA256-SHA:ECDH-RSA-AES256-SHA384:ECDH-ECDSA-AES256-SHA384:ECDH-RSA-AES256-SHA:ECDH-ECDSA-AES256-SHA:ECDH-RSA-CAMELLIA256-SHA384:ECDH-ECDSA-CAMELLIA256-SHA384:AES256-SHA256:AES256-SHA:CAMELLIA256-SHA256:CAMELLIA256-SHA:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:DHE-RSA-AES128-SHA256:DHE-DSS-AES128-SHA256:DH-RSA-AES128-SHA256:DH-DSS-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA:DH-RSA-AES128-SHA:DH-DSS-AES128-SHA:ECDHE-RSA-CAMELLIA128-SHA256:ECDHE-ECDSA-CAMELLIA128-SHA256:DHE-RSA-CAMELLIA128-SHA256:DHE-DSS-CAMELLIA128-SHA256:DH-RSA-CAMELLIA128-SHA256:DH-DSS-CAMELLIA128-SHA256:DHE-RSA-SEED-SHA:DHE-DSS-SEED-SHA:DH-RSA-SEED-SHA:DH-DSS-SEED-SHA:DHE-RSA-CAMELLIA128-SHA:DHE-DSS-CAMELLIA128-SHA:DH-RSA-CAMELLIA128-SHA:DH-DSS-CAMELLIA128-SHA:ECDH-RSA-AES128-SHA256:ECDH-ECDSA-AES128-SHA256:ECDH-RSA-AES128-SHA:ECDH-ECDSA-AES128-SHA:ECDH-RSA-CAMELLIA128-SHA256:ECDH-ECDSA-CAMELLIA128-SHA256:AES128-SHA256:AES128-SHA:CAMELLIA128-SHA256:SEED-SHA:CAMELLIA128-SHA:IDEA-CBC-SHA:ECDHE-RSA-DES-CBC3-SHA:ECDHE-ECDSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:EDH-DSS-DES-CBC3-SHA:DH-RSA-DES-CBC3-SHA:DH-DSS-DES-CBC3-SHA:ECDH-RSA-DES-CBC3-SHA:ECDH-ECDSA-DES-CBC3-SHA:DES-CBC3-SHA:EXP1024-DHE-DSS-DES-CBC-SHA:EDH-RSA-DES-CBC-SHA:EDH-DSS-DES-CBC-SHA:DH-RSA-DES-CBC-SHA:DH-DSS-DES-CBC-SHA:EXP1024-DES-CBC-SHA:DES-CBC-SHA:EXP-EDH-RSA-DES-CBC-SHA:EXP-EDH-DSS-DES-CBC-SHA:EXP-DES-CBC-SHA:EXP-RC2-CBC-MD5:EXP-DH-DSS-DES-CBC-SHA:EXP-DH-RSA-DES-CBC-SHA"
local cbc_cipher_list_hex="c0,28, c0,24, c0,14, c0,0a, 00,6b, 00,6a, 00,69, 00,68, 00,39, 00,38, 00,37, 00,36, c0,77, c0,73, 00,c4, 00,c3, 00,c2, 00,c1, 00,88, 00,87, 00,86, 00,85, c0,2a, c0,26, c0,0f, c0,05, c0,79, c0,75, 00,3d, 00,35, 00,c0, 00,84, c0,3d, c0,3f, c0,41, c0,43, c0,45, c0,49, c0,4b, c0,4d, c0,4f, c0,27, c0,23, c0,13, c0,09, 00,67, 00,40, 00,3f, 00,3e, 00,33, 00,32, 00,31, 00,30, c0,76, c0,72, 00,be, 00,bd, 00,bc, 00,bb, 00,9a, 00,99, 00,98, 00,97, 00,45, 00,44, 00,43, 00,42, c0,29, c0,25, c0,0e, c0,04, c0,78, c0,74, 00,3c, 00,2f, 00,ba, 00,96, 00,41, 00,07, c0,3c, c0,3e, c0,40, c0,42, c0,44, c0,48, c0,4a, c0,4c, c0,4e, c0,12, c0,08, 00,16, 00,13, 00,10, 00,0d, c0,0d, c0,03, 00,0a, fe,ff, ff,e0, 00,63, 00,15, 00,12, 00,0f, 00,0c, 00,62, 00,09, fe,fe, ff,e1, 00,14, 00,11, 00,08, 00,06, 00,0b, 00,0e"
local using_sockets=true local using_sockets=true
[[ "$OPTIMAL_PROTO" == "-ssl2" ]] && return 0 [[ "$OPTIMAL_PROTO" == "-ssl2" ]] && return 0
"$SSL_NATIVE" && using_sockets=false "$SSL_NATIVE" && using_sockets=false
if "$using_sockets"; then if "$using_sockets"; then
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 if [[ -z $STARTTLS ]]; then
for alpn_proto in $ALPN_PROTOs; do for alpn_proto in $ALPN_PROTOs; do
alpn+=",$(printf "%02x" ${#alpn_proto}),$(string_to_asciihex "$alpn_proto")" alpn+=",$(printf "%02x" ${#alpn_proto}),$(string_to_asciihex "$alpn_proto")"
@ -5183,11 +5186,16 @@ determine_tls_extensions() {
alpn_list_len_hex=$(printf "%04x" $alpn_list_len) alpn_list_len_hex=$(printf "%04x" $alpn_list_len)
alpn_extn_len=$alpn_list_len+2 alpn_extn_len=$alpn_list_len+2
alpn_extn_len_hex=$(printf "%04x" $alpn_extn_len) alpn_extn_len_hex=$(printf "%04x" $alpn_extn_len)
tls_sockets "03" "$TLS12_CIPHER" "all" "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, 00,10,${alpn_extn_len_hex:0:2},${alpn_extn_len_hex:2:2},${alpn_list_len_hex:0:2},${alpn_list_len_hex:2:2}$alpn" tls_extensions+=", 00,10,${alpn_extn_len_hex:0:2},${alpn_extn_len_hex:2:2},${alpn_list_len_hex:0:2},${alpn_list_len_hex:2:2}$alpn"
else fi
tls_sockets "03" "$TLS12_CIPHER" "all" "00,01,00,01,02, 00,02,00,00, 00,04,00,00, 00,12,00,00, 00,16,00,00, 00,17,00,00" if [[ ! "$TLS_EXTENSIONS" =~ "encrypt-then-mac" ]]; then
tls_sockets "03" "$cbc_cipher_list_hex, 00,ff" "all" "$tls_extensions"
success=$?
fi
if [[ $success -ne 0 ]] && [[ $success -ne 2 ]]; then
tls_sockets "03" "$TLS12_CIPHER" "all" "$tls_extensions"
success=$?
fi fi
success=$?
[[ $success -eq 2 ]] && success=0 [[ $success -eq 2 ]] && success=0
[[ $success -eq 0 ]] && tls_extensions="$(grep -a 'TLS Extensions: ' "$TEMPDIR/$NODEIP.parse_tls_serverhello.txt" | sed 's/TLS Extensions: //' )" [[ $success -eq 0 ]] && tls_extensions="$(grep -a 'TLS Extensions: ' "$TEMPDIR/$NODEIP.parse_tls_serverhello.txt" | sed 's/TLS Extensions: //' )"
if [[ -r "$TEMPDIR/$NODEIP.parse_tls_serverhello.txt" ]]; then if [[ -r "$TEMPDIR/$NODEIP.parse_tls_serverhello.txt" ]]; then
@ -5200,16 +5208,23 @@ determine_tls_extensions() {
elif "$HAS_SPDY" && [[ -z $STARTTLS ]]; then elif "$HAS_SPDY" && [[ -z $STARTTLS ]]; then
params="-nextprotoneg \"$NPN_PROTOs\"" params="-nextprotoneg \"$NPN_PROTOs\""
fi fi
success=1
addcmd="" addcmd=""
if [[ -z "$OPTIMAL_PROTO" ]] && [[ -z "$SNI" ]] && "$HAS_NO_SSL2"; then if [[ -z "$OPTIMAL_PROTO" ]] && [[ -z "$SNI" ]] && "$HAS_NO_SSL2"; then
addcmd="-no_ssl2" addcmd="-no_ssl2"
elif [[ ! "$OPTIMAL_PROTO" =~ ssl ]]; then elif [[ ! "$OPTIMAL_PROTO" =~ ssl ]]; then
addcmd="$SNI" addcmd="$SNI"
fi fi
$OPENSSL s_client $STARTTLS $BUGS -connect $NODEIP:$PORT $PROXY $addcmd $OPTIMAL_PROTO -tlsextdebug $params </dev/null 2>$ERRFILE >$TMPFILE if [[ ! "$TLS_EXTENSIONS" =~ "encrypt-then-mac" ]]; then
sclient_connect_successful $? $TMPFILE $OPENSSL s_client $STARTTLS $BUGS -connect $NODEIP:$PORT $PROXY $addcmd $OPTIMAL_PROTO -tlsextdebug $params -cipher $cbc_cipher_list </dev/null 2>$ERRFILE >$TMPFILE
if [[ $? -eq 0 ]]; then sclient_connect_successful $? $TMPFILE
success=$?
fi
if [[ $success -ne 0 ]]; then
$OPENSSL s_client $STARTTLS $BUGS -connect $NODEIP:$PORT $PROXY $addcmd $OPTIMAL_PROTO -tlsextdebug $params </dev/null 2>$ERRFILE >$TMPFILE
sclient_connect_successful $? $TMPFILE
success=$?
fi
if [[ $success -eq 0 ]]; then
success=0 success=0
tls_extensions=$(grep -a 'TLS server extension ' $TMPFILE | sed -e 's/TLS server extension //g' -e 's/\" (id=/\/#/g' -e 's/,.*$/,/g' -e 's/),$/\"/g') tls_extensions=$(grep -a 'TLS server extension ' $TMPFILE | sed -e 's/TLS server extension //g' -e 's/\" (id=/\/#/g' -e 's/,.*$/,/g' -e 's/),$/\"/g')
tls_extensions=$(echo $tls_extensions) # into one line tls_extensions=$(echo $tls_extensions) # into one line