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Update ciphers for server preference

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This PR was developed in response to #845. It adds to the list of ciphers used to determine whether the server has a cipher order in order to help avoid cases in which testssl.sh cannot determine a cipher order.

In order to create this list I scanned thousands of servers in order to determine what ciphers they support, including (1) about 20 thousand U.S. government web sites, (2) all of the sites listed at badssl.com, (3) all of the test servers listed at https://github.com/tlswg/tls13-spec/wiki/implementations, (4) about 30 additional non-U.S. government sites, and (5) one server configured as described in #845. I scanned each of these servers using OpenSSL 1.0.2-chacha, 1.0.2o, and 1.1.1.

Then I ran collection information through a script that created the updated list. For each scanned server, and for each of the 3 versions of OpenSSL, the script checked whether $list_fwd contained at least two ciphers from the list. If it didn't, then it would add one of the ciphers supported by the server (and by OpenSSL) to the list. In choosing among the ciphers supported by the server that were not already in $list_fwd, it would choose the cipher that was supported by the most other servers.

The list contain a few oddities as a result of the servers that I scanned. The script added two TLSv1.3 ciphers, since I scanned at least one server that only supports TLSv1.3. The list also includes ADH-AES256-GCM-SHA384 and AECDH-AES128-SHA, which may only be supported by null.badssl.com.

I made one manual change to the list - adding TLS_CHACHA20_POLY1305_SHA256. I did this since the number of TLSv1.3 servers scanned was so small, I didn't think it was safe to assume that all servers that support TLSv1.3 would support both TLS_AES_256_GCM_SHA384 and TLS_AES_128_GCM_SHA256.

Since most of the servers that I scanned were U.S. government servers, it may not be a representative sample. However, since the new list only adds to the current list, it can only be an improvement. Also, the updated list still only includes 37 ciphers, so many more could be added without creating any problems.
This commit is contained in:
David Cooper 2018-04-25 16:21:38 -04:00 committed by GitHub
parent 90b671fbb3
commit d257dae5d5
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 11 additions and 10 deletions
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testssl.sh
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@ -5422,9 +5422,10 @@ run_server_preference() {
local -a cipher proto
local proto_ossl proto_txt proto_hex cipherlist i
local -i ret=0 j sclient_success str_len
local list_fwd="DES-CBC3-SHA:RC4-MD5:DES-CBC-SHA:RC4-SHA:AES128-SHA:AES128-SHA256:AES256-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA:ECDH-RSA-DES-CBC3-SHA:ECDH-RSA-AES128-SHA:ECDH-RSA-AES256-SHA:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:DHE-DSS-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:AES256-SHA256"
# now reversed offline via tac, see https://github.com/thomassa/testssl.sh/commit/7a4106e839b8c3033259d66697893765fc468393 :
local list_reverse="AES256-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-DSS-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDH-RSA-AES256-SHA:ECDH-RSA-AES128-SHA:ECDH-RSA-DES-CBC3-SHA:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:ECDHE-RSA-AES128-SHA:AES256-SHA:AES128-SHA256:AES128-SHA:RC4-SHA:DES-CBC-SHA:RC4-MD5:DES-CBC3-SHA"
local list_fwd="DES-CBC3-SHA:RC4-MD5:DES-CBC-SHA:RC4-SHA:AES128-SHA:AES128-SHA256:AES256-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA:ECDH-RSA-DES-CBC3-SHA:ECDH-RSA-AES128-SHA:ECDH-RSA-AES256-SHA:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:DHE-DSS-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:AES256-SHA256:ECDHE-RSA-DES-CBC3-SHA:ECDHE-RSA-AES128-SHA256:AES256-GCM-SHA384:AES128-GCM-SHA256:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-SHA256:ADH-AES256-GCM-SHA384:AECDH-AES128-SHA:ECDHE-RSA-RC4-SHA:ECDHE-ECDSA-AES128-SHA"
local list_reverse="ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-RC4-SHA:AECDH-AES128-SHA:ADH-AES256-GCM-SHA384:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-GCM-SHA256:AES128-GCM-SHA256:AES256-GCM-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-DES-CBC3-SHA:AES256-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-DSS-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDH-RSA-AES256-SHA:ECDH-RSA-AES128-SHA:ECDH-RSA-DES-CBC3-SHA:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:ECDHE-RSA-AES128-SHA:AES256-SHA:AES128-SHA256:AES128-SHA:RC4-SHA:DES-CBC-SHA:RC4-MD5:DES-CBC3-SHA"
tls13_list_fwd="TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256"
tls13_list_reverse="TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384"
local has_cipher_order=false
local addcmd="" addcmd2=""
local using_sockets=true
@ -5446,11 +5447,11 @@ run_server_preference() {
# and the -no_ssl2 isn't provided.
addcmd="-no_ssl2 $SNI"
fi
$OPENSSL s_client $(s_client_options "$STARTTLS -cipher $list_fwd $BUGS -connect $NODEIP:$PORT $PROXY $addcmd") </dev/null 2>$ERRFILE >$TMPFILE
$OPENSSL s_client $(s_client_options "$STARTTLS -cipher $list_fwd -ciphersuites $tls13_list_fwd $BUGS -connect $NODEIP:$PORT $PROXY $addcmd") </dev/null 2>$ERRFILE >$TMPFILE
if ! sclient_connect_successful $? $TMPFILE && [[ -z "$STARTTLS_PROTOCOL" ]]; then
pr_warning "no matching cipher in this list found (pls report this): "
outln "$list_fwd . "
fileout "$jsonID" "WARN" "Could not determine server cipher order, no matching cipher in list found (pls report this): $list_fwd"
outln "$list_fwd:$tls13_list_fwd . "
fileout "$jsonID" "WARN" "Could not determine server cipher order, no matching cipher in list found (pls report this): $list_fwd:$tls13_list_fwd"
tmpfile_handle ${FUNCNAME[0]}.txt
return 1
# we assume the problem is with testing here but it could be also the server side
@ -5460,11 +5461,11 @@ run_server_preference() {
debugme tm_out "(workaround #188) "
determine_optimal_proto $STARTTLS_PROTOCOL
[[ ! "$STARTTLS_OPTIMAL_PROTO" =~ ssl ]] && addcmd2="$SNI"
$OPENSSL s_client $(s_client_options "$STARTTLS $STARTTLS_OPTIMAL_PROTO -cipher $list_fwd $BUGS -connect $NODEIP:$PORT $PROXY $addcmd2") </dev/null 2>$ERRFILE >$TMPFILE
$OPENSSL s_client $(s_client_options "$STARTTLS $STARTTLS_OPTIMAL_PROTO -cipher $list_fwd -ciphersuites $tls13_list_fwd $BUGS -connect $NODEIP:$PORT $PROXY $addcmd2") </dev/null 2>$ERRFILE >$TMPFILE
if ! sclient_connect_successful $? $TMPFILE; then
pr_warning "no matching cipher in this list found (pls report this): "
outln "$list_fwd . "
fileout "$jsonID" "WARN" "Could not determine cipher order, no matching cipher in list found (pls report this): $list_fwd"
outln "$list_fwd:$tls13_list_fwd . "
fileout "$jsonID" "WARN" "Could not determine cipher order, no matching cipher in list found (pls report this): $list_fwd:$tls13_list_fwd"
tmpfile_handle ${FUNCNAME[0]}.txt
return 1
fi
@ -5482,7 +5483,7 @@ run_server_preference() {
fi
# second client hello with reverse list
$OPENSSL s_client $(s_client_options "$STARTTLS -cipher $list_reverse $BUGS -connect $NODEIP:$PORT $PROXY $addcmd2") </dev/null 2>>$ERRFILE >$TMPFILE
$OPENSSL s_client $(s_client_options "$STARTTLS -cipher $list_reverse -ciphersuites $tls13_list_reverse $BUGS -connect $NODEIP:$PORT $PROXY $addcmd2") </dev/null 2>>$ERRFILE >$TMPFILE
# first handshake worked above so no error handling here
cipher2=$(get_cipher $TMPFILE) # cipher2 from 2nd serverhello