#はじめに
IPAの「TLS暗号設定ガイドライン～安全なウェブサイトのために（暗号設定対策編）～」に沿って、CentOS8のSSLの設定を行ってみた。
#実施範囲
今回は、ローカル環境においてオレオレ証明書を使ったため、「TLS暗号設定ガイドライン チェックリスト」における②プロトコルバージョン設定、④暗号スイート設定を対象とし、③サーバ証明書設定は対象外とした。
また、「推奨セキュリティ型」、「高セキュリティ型」、「セキュリティ例外型」のうち**「推奨セキュリティ型]を「TLSv1.3あり」**で実施した。
さらにローカル環境ということで、設定内容の確認として、SSL Server Test (https://www.ssllabs.com/ssltest/) は使わずに、フリーソフトウェア testssl.sh (https://github.com/drwetter/testssl.sh) を用いた確認を実施した。
#環境
- CentOS 8.1
- Apache+mod_ssl 2.4.37
- OpenSSL 1.1.1
#手順
プロトコルバージョンの設定
今回、TLS1.2と1.3を使うため、以下のようにする。
/etc/httpd/conf.d/ssl.conf
SSLProtocol TLSv1.2 +TLSv1.3
暗号スイート設定
TLS1.2、1.3の推奨セキュリティ型設定を以下のように追加する(TLS暗号設定 暗号スイートの設定例参照)。
/etc/httpd/conf.d/ssl.conf
SSLCipherSuite "ECDHE+AESGCM:DHE+aRSA+AESGCM:ECDHE+AESCCM:DHE+aRSA+AESCCM:+AES256:ECDHE+CHACHA20:DHE+aRSA+CHACHA20:+DHE:ECDHE+AES128:ECDHE+CAMELLIA128:ECDHE+AES:ECDHE+CAMELLIA:+ECDHE+SHA:DHE+aRSA+AES128:DHE+aRSA+CAMELLIA128:DHE+aRSA+AES:DHE+aRSA+CAMELLIA:+DHE+aRSA+SHA"
SSLCipherSuite TLSv1.3 "TLS_AES_128_GCM_SHA256:TLS_AES_128_CCM_SHA256:TLS_AES_128_CCM_8_SHA256:TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256"
暗号スイート順序サーバ優先設定
以下を追加する
/etc/httpd/conf.d/ssl.conf
<VirtualHost _default_:443>
（中略）
SSLHonorCipherOrder On
<VirtualHost>
鍵交換パラメータの設定
###OpenSSL による DHE パラメータファイルの生成
以下により生成する。結構時間がかかる。
openssl dhparam -out dh2048.pem -outform PEM 2048
###DHE 鍵交換で使用するグループのパラメータファイルによる指定
SSLCertificateFileで指定したファイルに、dh2048.pemを追加する。
cat /etc/httpd/conf.d/ssl.cert/server.crt dh2048.pem > /etc/httpd/conf.d/ssl.cert/server_dh2048.crt
SSLCertificateFileの設定を上の出力ファイルに変更する。
/etc/httpd/conf/httpd.conf
SSLCertificateFile /etc/httpd/conf.d/ssl.cert/server_dh2048.crt
###ECDHE 鍵交換で使用するグループの設定
以下を追加する
/etc/httpd/conf/httpd.conf
SSLOpenSSLConfCmd Groups "X25519:X448:P-256:P-384:P-521"
HTTP Strict Transport Security（HSTS）の設定
以下を追加する
/etc/httpd/conf/httpd.conf
Header always set Strict-Transport-Security "max-age=31536000; includeSubDomains"
OCSP stapling の設定
以下を追加する
/etc/httpd/conf.d/ssl.conf
SSLStaplingCache "shmcb:/var/run/httpd/stapling_cache(32768)"
<VirtualHost *:443>
（中略）
SSLUseStapling on
</VirtualHost>
設定内容の確認
testssl.shのインストール
git clone https://github.com/drwetter/testssl.sh
testssl.shによる確認
以下コマンドを実行
$cd testssl.sh
$./testssl.sh localhost
確認結果
[root@localhost testssl.sh]# ./testssl.sh localhost
###########################################################
testssl.sh 3.1dev from https://testssl.sh/dev/
(b4c9437 2020-10-03 10:21:31 -- )
This program is free software. Distribution and
modification under GPLv2 permitted.
USAGE w/o ANY WARRANTY. USE IT AT YOUR OWN RISK!
Please file bugs @ https://testssl.sh/bugs/
###########################################################
Using "OpenSSL 1.0.2-chacha (1.0.2k-dev)" [~183 ciphers]
on localhost:./bin/openssl.Linux.x86_64
(built: "Jan 18 17:12:17 2019", platform: "linux-x86_64")
Start 2020-09-29 01:42:44 -->> 127.0.0.1:443 (localhost) <<--
rDNS (127.0.0.1): localhost.
Service detected: HTTP
Testing protocols via sockets except NPN+ALPN
SSLv2 not offered (OK)
SSLv3 not offered (OK)
TLS 1 not offered
TLS 1.1 not offered
TLS 1.2 offered (OK)
TLS 1.3 offered (OK): final
NPN/SPDY not offered
ALPN/HTTP2 http/1.1 (offered)
Testing cipher categories
NULL ciphers (no encryption) not offered (OK)
Anonymous NULL Ciphers (no authentication) not offered (OK)
Export ciphers (w/o ADH+NULL) not offered (OK)
LOW: 64 Bit + DES, RC[2,4], MD5 (w/o export) not offered (OK)
Triple DES Ciphers / IDEA not offered
Obsoleted CBC ciphers (AES, ARIA etc.) offered
Strong encryption (AEAD ciphers) with no FS not offered
Forward Secrecy strong encryption (AEAD ciphers) offered (OK)
Testing server's cipher preferences
Has server cipher order? yes (OK) -- TLS 1.3 and below
Negotiated protocol TLSv1.3
Negotiated cipher TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Cipher per protocol
Hexcode Cipher Suite Name (OpenSSL) KeyExch. Encryption Bits Cipher Suite Name (IANA/RFC)
-----------------------------------------------------------------------------------------------------------------------------
SSLv2
-
SSLv3
-
TLSv1
-
TLSv1.1
-
TLSv1.2 (server order)
xc02f ECDHE-RSA-AES128-GCM-SHA256 ECDH 253 AESGCM 128 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
xc030 ECDHE-RSA-AES256-GCM-SHA384 ECDH 253 AESGCM 256 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
xcca8 ECDHE-RSA-CHACHA20-POLY1305 ECDH 253 ChaCha20 256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
x9e DHE-RSA-AES128-GCM-SHA256 DH 2048 AESGCM 128 TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
xc0a2 DHE-RSA-AES128-CCM8 DH 2048 AESCCM8 128 TLS_DHE_RSA_WITH_AES_128_CCM_8
xc09e DHE-RSA-AES128-CCM DH 2048 AESCCM 128 TLS_DHE_RSA_WITH_AES_128_CCM
x9f DHE-RSA-AES256-GCM-SHA384 DH 2048 AESGCM 256 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
xc0a3 DHE-RSA-AES256-CCM8 DH 2048 AESCCM8 256 TLS_DHE_RSA_WITH_AES_256_CCM_8
xc09f DHE-RSA-AES256-CCM DH 2048 AESCCM 256 TLS_DHE_RSA_WITH_AES_256_CCM
xccaa DHE-RSA-CHACHA20-POLY1305 DH 2048 ChaCha20 256 TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256
xc027 ECDHE-RSA-AES128-SHA256 ECDH 253 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
xc076 ECDHE-RSA-CAMELLIA128-SHA256 ECDH 253 Camellia 128 TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256
xc028 ECDHE-RSA-AES256-SHA384 ECDH 253 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
xc077 ECDHE-RSA-CAMELLIA256-SHA384 ECDH 253 Camellia 256 TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384
xc013 ECDHE-RSA-AES128-SHA ECDH 253 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
xc014 ECDHE-RSA-AES256-SHA ECDH 253 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
x67 DHE-RSA-AES128-SHA256 DH 2048 AES 128 TLS_DHE_RSA_WITH_AES_128_CBC_SHA256
xbe DHE-RSA-CAMELLIA128-SHA256 DH 2048 Camellia 128 TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA256
x6b DHE-RSA-AES256-SHA256 DH 2048 AES 256 TLS_DHE_RSA_WITH_AES_256_CBC_SHA256
xc4 DHE-RSA-CAMELLIA256-SHA256 DH 2048 Camellia 256 TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA256
x33 DHE-RSA-AES128-SHA DH 2048 AES 128 TLS_DHE_RSA_WITH_AES_128_CBC_SHA
x45 DHE-RSA-CAMELLIA128-SHA DH 2048 Camellia 128 TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA
x39 DHE-RSA-AES256-SHA DH 2048 AES 256 TLS_DHE_RSA_WITH_AES_256_CBC_SHA
x88 DHE-RSA-CAMELLIA256-SHA DH 2048 Camellia 256 TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA
TLSv1.3 (server order)
x1301 TLS_AES_128_GCM_SHA256 ECDH 253 AESGCM 128 TLS_AES_128_GCM_SHA256
x1304 TLS_AES_128_CCM_SHA256 ECDH 253 AESCCM 128 TLS_AES_128_CCM_SHA256
x1305 TLS_AES_128_CCM_8_SHA256 ECDH 253 AESCCM8 128 TLS_AES_128_CCM_8_SHA256
x1302 TLS_AES_256_GCM_SHA384 ECDH 253 AESGCM 256 TLS_AES_256_GCM_SHA384
x1303 TLS_CHACHA20_POLY1305_SHA256 ECDH 253 ChaCha20 256 TLS_CHACHA20_POLY1305_SHA256
Testing robust forward secrecy (FS) -- omitting Null Authentication/Encryption, 3DES, RC4
FS is offered (OK) TLS_AES_256_GCM_SHA384 TLS_CHACHA20_POLY1305_SHA256 ECDHE-RSA-AES256-GCM-SHA384
ECDHE-RSA-AES256-SHA384 ECDHE-RSA-AES256-SHA DHE-RSA-AES256-GCM-SHA384
ECDHE-RSA-CHACHA20-POLY1305 DHE-RSA-CHACHA20-POLY1305 DHE-RSA-AES256-CCM8
DHE-RSA-AES256-CCM DHE-RSA-AES256-SHA256 DHE-RSA-AES256-SHA
ECDHE-RSA-CAMELLIA256-SHA384 DHE-RSA-CAMELLIA256-SHA256 DHE-RSA-CAMELLIA256-SHA
TLS_AES_128_GCM_SHA256 TLS_AES_128_CCM_SHA256 TLS_AES_128_CCM_8_SHA256
ECDHE-RSA-AES128-GCM-SHA256 ECDHE-RSA-AES128-SHA256 ECDHE-RSA-AES128-SHA
DHE-RSA-AES128-GCM-SHA256 DHE-RSA-AES128-CCM8 DHE-RSA-AES128-CCM
DHE-RSA-AES128-SHA256 DHE-RSA-AES128-SHA ECDHE-RSA-CAMELLIA128-SHA256
DHE-RSA-CAMELLIA128-SHA256 DHE-RSA-CAMELLIA128-SHA
Elliptic curves offered: prime256v1 secp384r1 secp521r1 X25519 X448
DH group offered: Unknown DH group (2048 bits)
Testing server defaults (Server Hello)
TLS extensions (standard) "renegotiation info/#65281" "EC point formats/#11" "session ticket/#35"
"supported versions/#43" "key share/#51" "supported_groups/#10"
"max fragment length/#1" "application layer protocol negotiation/#16"
"encrypt-then-mac/#22" "extended master secret/#23"
Session Ticket RFC 5077 hint 300 seconds, session tickets keys seems to be rotated < daily
SSL Session ID support yes
Session Resumption Tickets: yes, ID: yes
TLS clock skew Random values, no fingerprinting possible
Signature Algorithm SHA256 with RSA
Server key size RSA 2048 bits (exponent is 65537)
Server key usage --
Server extended key usage --
Serial / Fingerprints 10E4C9CA96C8D66CDBEBA985B85AFF1CC115E500 / SHA1 6719A785AAFC505E5B2B0247DB30C66D2971288A
SHA256 B1552EA11105499B23708A1902EA781EC8BB2DF16A05C6ED7EB871E1A7E02812
Common Name (CN) (no CN field in subject)
subjectAltName (SAN) missing (NOT ok) -- Browsers are complaining
Trust (hostname) certificate does not match supplied URI (same w/o SNI)
Chain of trust NOT ok (self signed)
EV cert (experimental) no
Certificate Validity (UTC) 28 >= 60 days (2020-09-27 11:34 --> 2020-10-27 11:34)
ETS/"eTLS", visibility info not present
Certificate Revocation List --
OCSP URI --
NOT ok -- neither CRL nor OCSP URI provided
OCSP stapling not offered
OCSP must staple extension --
DNS CAA RR (experimental) not offered
Certificate Transparency --
Certificates provided 1
Issuer (Default Company Ltd from XX)
Intermediate Bad OCSP (exp.) Ok
Testing HTTP header response @ "/"
HTTP Status Code 200 OK
HTTP clock skew 0 sec from localtime
Strict Transport Security 365 days=31536000 s, includeSubDomains
Public Key Pinning --
Server banner Apache
Application banner --
Cookie(s) (none issued at "/")
Security headers --
Reverse Proxy banner --
Testing vulnerabilities
Heartbleed (CVE-2014-0160) not vulnerable (OK), no heartbeat extension
CCS (CVE-2014-0224) not vulnerable (OK)
Ticketbleed (CVE-2016-9244), experiment. not vulnerable (OK)
ROBOT Server does not support any cipher suites that use RSA key transport
Secure Renegotiation (RFC 5746) supported (OK)
Secure Client-Initiated Renegotiation not vulnerable (OK)
CRIME, TLS (CVE-2012-4929) not vulnerable (OK)
BREACH (CVE-2013-3587) no gzip/deflate/compress/br HTTP compression (OK) - only supplied "/" tested
POODLE, SSL (CVE-2014-3566) not vulnerable (OK), no SSLv3 support
TLS_FALLBACK_SCSV (RFC 7507) No fallback possible (OK), no protocol below TLS 1.2 offered
SWEET32 (CVE-2016-2183, CVE-2016-6329) not vulnerable (OK)
FREAK (CVE-2015-0204) not vulnerable (OK)
DROWN (CVE-2016-0800, CVE-2016-0703) not vulnerable on this host and port (OK)
make sure you don't use this certificate elsewhere with SSLv2 enabled services
https://censys.io/ipv4?q=B1552EA11105499B23708A1902EA781EC8BB2DF16A05C6ED7EB871E1A7E02812 could help you to find out
LOGJAM (CVE-2015-4000), experimental not vulnerable (OK): no DH EXPORT ciphers, no common prime detected
BEAST (CVE-2011-3389) not vulnerable (OK), no SSL3 or TLS1
LUCKY13 (CVE-2013-0169), experimental potentially VULNERABLE, uses cipher block chaining (CBC) ciphers with TLS. Check patches
Winshock (CVE-2014-6321), experimental not vulnerable (OK)
RC4 (CVE-2013-2566, CVE-2015-2808) no RC4 ciphers detected (OK)
Running client simulations (HTTP) via sockets
Android 4.4.2 TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
Android 5.0.0 TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
Android 6.0 TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
Android 7.0 (native) TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
Android 8.1 (native) TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 253 bit ECDH (X25519)
Android 9.0 (native) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Android 10.0 (native) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Chrome 74 (Win 10) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Chrome 79 (Win 10) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Firefox 66 (Win 8.1/10) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Firefox 71 (Win 10) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
IE 6 XP No connection
IE 8 Win 7 No connection
IE 8 XP No connection
IE 11 Win 7 TLSv1.2 DHE-RSA-AES128-GCM-SHA256, 2048 bit DH
IE 11 Win 8.1 TLSv1.2 DHE-RSA-AES128-GCM-SHA256, 2048 bit DH
IE 11 Win Phone 8.1 TLSv1.2 ECDHE-RSA-AES128-SHA256, 256 bit ECDH (P-256)
IE 11 Win 10 TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
Edge 15 Win 10 TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 253 bit ECDH (X25519)
Edge 17 (Win 10) TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 253 bit ECDH (X25519)
Opera 66 (Win 10) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Safari 9 iOS 9 TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
Safari 9 OS X 10.11 TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
Safari 10 OS X 10.12 TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
Safari 12.1 (iOS 12.2) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Safari 13.0 (macOS 10.14.6) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Apple ATS 9 iOS 9 TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
Java 6u45 No connection
Java 7u25 No connection
Java 8u161 TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
Java 11.0.2 (OpenJDK) TLSv1.3 TLS_AES_128_GCM_SHA256, 256 bit ECDH (P-256)
Java 12.0.1 (OpenJDK) TLSv1.3 TLS_AES_128_GCM_SHA256, 256 bit ECDH (P-256)
OpenSSL 1.0.2e TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
OpenSSL 1.1.0l (Debian) TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 253 bit ECDH (X25519)
OpenSSL 1.1.1d (Debian) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Thunderbird (68.3) TLSv1.3 TLS_AES_128_GCM_SHA256, 253 bit ECDH (X25519)
Rating (experimental)
Rating specs (not complete) SSL Labs's 'SSL Server Rating Guide' (version 2009q from 2020-01-30)
Specification documentation https://github.com/ssllabs/research/wiki/SSL-Server-Rating-Guide
Protocol Support (weighted) 0 (0)
Key Exchange (weighted) 0 (0)
Cipher Strength (weighted) 0 (0)
Final Score 0
Overall Grade T
Grade cap reasons Grade capped to T. Issues with the chain of trust (self signed)
Grade capped to M. Domain name mismatch
Done 2020-09-29 01:44:26 [ 103s] -->> 127.0.0.1:443 (localhost) <<--
考察
- 証明書関連、ドメイン名のミスマッチの脆弱性が残っているが、暗号系はOKっぽい？
- OCSP stapling 関連が not OK、not offeredとなっている。オレオレ証明書が原因くさい。
- DH group offered が"Unknown DH group (2048 bits)"となっているが、"鍵交換パラメータの設定"の設定をしなかった場合、何等かのグループ名が設定されており2048ビットになっている。"鍵交換パラメータの設定"はあえて設定する必要はない？
- LUCKY13 (CVE-2013-0169), experimental の脆弱性がでているが、これはTLS1.2の暗号スイートを「高セキュリティ型設定」に変更すると消える。
#参考