CipherScan

$ ./cipherscan jve.linuxwall.info
........................
Target: jve.linuxwall.info:443

prio  ciphersuite                  protocols              pfs_keysize
1     ECDHE-RSA-AES128-GCM-SHA256  TLSv1.2                ECDH,P-256,256bits
2     ECDHE-RSA-AES256-GCM-SHA384  TLSv1.2                ECDH,P-256,256bits
3     DHE-RSA-AES128-GCM-SHA256    TLSv1.2                DH,2048bits
4     DHE-RSA-AES256-GCM-SHA384    TLSv1.2                DH,2048bits
5     ECDHE-RSA-AES128-SHA256      TLSv1.2                ECDH,P-256,256bits
6     ECDHE-RSA-AES128-SHA         TLSv1,TLSv1.1,TLSv1.2  ECDH,P-256,256bits
7     ECDHE-RSA-AES256-SHA384      TLSv1.2                ECDH,P-256,256bits
8     ECDHE-RSA-AES256-SHA         TLSv1,TLSv1.1,TLSv1.2  ECDH,P-256,256bits
9     DHE-RSA-AES128-SHA256        TLSv1.2                DH,2048bits
10    DHE-RSA-AES128-SHA           TLSv1,TLSv1.1,TLSv1.2  DH,2048bits
11    DHE-RSA-AES256-SHA256        TLSv1.2                DH,2048bits
12    DHE-RSA-AES256-SHA           TLSv1,TLSv1.1,TLSv1.2  DH,2048bits
13    AES128-GCM-SHA256            TLSv1.2
14    AES256-GCM-SHA384            TLSv1.2
15    AES128-SHA256                TLSv1.2
16    AES256-SHA256                TLSv1.2
17    AES128-SHA                   TLSv1,TLSv1.1,TLSv1.2
18    AES256-SHA                   TLSv1,TLSv1.1,TLSv1.2
19    DHE-RSA-CAMELLIA256-SHA      TLSv1,TLSv1.1,TLSv1.2  DH,2048bits
20    CAMELLIA256-SHA              TLSv1,TLSv1.1,TLSv1.2
21    DHE-RSA-CAMELLIA128-SHA      TLSv1,TLSv1.1,TLSv1.2  DH,2048bits
22    CAMELLIA128-SHA              TLSv1,TLSv1.1,TLSv1.2
23    DES-CBC3-SHA                 TLSv1,TLSv1.1,TLSv1.2

Certificate: trusted, 2048 bit, sha256WithRSAEncryption signature
TLS ticket lifetime hint: 300
OCSP stapling: not supported
Server side cipher ordering

Cipherscan tests the ordering of the SSL/TLS ciphers on a given target, for all major versions of SSL and TLS. It also extracts some certificates informations, TLS options, OCSP stapling and more. Cipherscan is a wrapper above the openssl s_client command line.

Cipherscan is meant to run on all flavors of unix. It ships with its own built of OpenSSL for Linux/64 and Darwin/64. On other platform, it will use the openssl version provided by the operating system (which may have limited ciphers support), or your own version provided in the -o command line flag.

Examples

Basic test:

$ ./cipherscan google.com
...................
Target: google.com:443

prio  ciphersuite                  protocols                    pfs_keysize
1     ECDHE-RSA-CHACHA20-POLY1305  TLSv1.2                      ECDH,P-256,256bits
2     ECDHE-RSA-AES128-GCM-SHA256  TLSv1.2                      ECDH,P-256,256bits
3     ECDHE-RSA-AES128-SHA         TLSv1.1,TLSv1.2              ECDH,P-256,256bits
4     ECDHE-RSA-RC4-SHA            SSLv3,TLSv1,TLSv1.1,TLSv1.2  ECDH,P-256,256bits
5     AES128-GCM-SHA256            TLSv1.2
6     AES128-SHA256                TLSv1.2
7     AES128-SHA                   TLSv1.1,TLSv1.2
8     RC4-SHA                      SSLv3,TLSv1,TLSv1.1,TLSv1.2
9     RC4-MD5                      SSLv3,TLSv1,TLSv1.1,TLSv1.2
10    ECDHE-RSA-AES256-GCM-SHA384  TLSv1.2                      ECDH,P-256,256bits
11    ECDHE-RSA-AES256-SHA384      TLSv1.2                      ECDH,P-256,256bits
12    ECDHE-RSA-AES256-SHA         SSLv3,TLSv1,TLSv1.1,TLSv1.2  ECDH,P-256,256bits
13    AES256-GCM-SHA384            TLSv1.2
14    AES256-SHA256                TLSv1.2
15    AES256-SHA                   SSLv3,TLSv1,TLSv1.1,TLSv1.2
16    ECDHE-RSA-AES128-SHA256      TLSv1.2                      ECDH,P-256,256bits
17    ECDHE-RSA-DES-CBC3-SHA       SSLv3,TLSv1,TLSv1.1,TLSv1.2  ECDH,P-256,256bits
18    DES-CBC3-SHA                 SSLv3,TLSv1,TLSv1.1,TLSv1.2

Certificate: trusted, 2048 bit, sha1WithRSAEncryption signature
TLS ticket lifetime hint: 100800
OCSP stapling: not supported
Server side cipher ordering

Testing STARTTLS:

darwin $ ./cipherscan -o ./openssl-mine -starttls xmpp jabber.ccc.de:5222
.........
.........
prio  ciphersuite           protocols    pfs_keysize
1     DHE-RSA-AES256-SHA    SSLv3,TLSv1  DH,1024bits
2     AES256-SHA            SSLv3,TLSv1
3     EDH-RSA-DES-CBC3-SHA  SSLv3,TLSv1  DH,1024bits
4     DES-CBC3-SHA          SSLv3,TLSv1
5     DHE-RSA-AES128-SHA    SSLv3,TLSv1  DH,1024bits
6     AES128-SHA            SSLv3,TLSv1
7     RC4-SHA               SSLv3,TLSv1
8     RC4-MD5               SSLv3,TLSv1

Certificate: UNTRUSTED, 2048 bit, sha1WithRSAEncryption signature

Exporting to JSON with the -j command line option:

$ /cipherscan -j -starttls xmpp jabber.ccc.de:5222
{
    "target": "jabber.ccc.de:5222",
    "date": "Sat, 19 Apr 2014 11:40:40 -0400",
    "ciphersuite": [
        {
            "cipher": "DHE-RSA-AES256-SHA",
            "protocols": [
                "SSLv3",
                "TLSv1"
            ],
            "pubkey": [
                "2048"
            ],
            "sigalg": [
                "sha1WithRSAEncryption"
            ],
            "trusted": "False",
            "pfs": "DH,1024bits"
        }
    ]
}

Analyzing configurations

The motivation behind cipherscan is to help operators configure good TLS on their endpoints. To help this further, the script analyze.py compares the results of a cipherscan with the TLS guidelines from https://wiki.mozilla.org/Security/Server_Side_TLS and output a level and recommendations.

$ ./analyze.py -t jve.linuxwall.info
jve.linuxwall.info:443 has intermediate tls

Changes needed to match the old level:
* consider enabling SSLv3
* add cipher DES-CBC3-SHA
* use a certificate with sha1WithRSAEncryption signature
* consider enabling OCSP Stapling

Changes needed to match the intermediate level:
* consider enabling OCSP Stapling

Changes needed to match the modern level:
* remove cipher AES128-GCM-SHA256
* remove cipher AES256-GCM-SHA384
* remove cipher AES128-SHA256
* remove cipher AES128-SHA
* remove cipher AES256-SHA256
* remove cipher AES256-SHA
* disable TLSv1
* consider enabling OCSP Stapling

In the output above, analyze.py indicates that the target jve.linuxwall.info matches the intermediate configuration level. If the administrator of this site wants to reach the modern level, the items that failed under the modern tests should be corrected.

analyze.py does not make any assumption on what a good level should be. Sites operators should now what level they want to match against, based on the compatibility level they want to support. Again, refer to https://wiki.mozilla.org/Security/Server_Side_TLS for more information.

Note on Nagios mode: analyse.py can be ran as a nagios check with --nagios. The exit code will then represent the state of the configuration:

• 2 (critical) for bad tls
• 1 (warning) if it doesn't match the desired level
• 0 (ok) if it matches. cipherscan can take more than 10 seconds to complete. To alleviate any timeout issues, you may want to run it outside of nagios, passing data through some temporary file.

OpenSSL

Cipherscan uses a custom release of openssl for linux 64 bits and darwin 64 bits. OpenSSL is build from a custom branch maintained by Peter Mosmans that includes a number of patches not merged upstream. It can be found here: https://github.com/PeterMosmans/openssl

You can build it yourself using following commands:

git clone https://github.com/PeterMosmans/openssl.git --depth 1 -b 1.0.2-chacha
cd openssl
./Configure zlib no-shared experimental-jpake enable-md2 enable-rc5 \
enable-rfc3779 enable-gost enable-static-engine linux-x86_64
make depend
make
make report

The statically linked binary will be apps/openssl.

Contributors

• Julien Vehent julien@linuxwall.info (original author)
• Hubert Kario hkario@redhat.com
• Pepi Zawodsky git@maclemon.at
• Michael Zeltner m@niij.org
• Simon Deziel simon.deziel@gmail.com