112 lines
4.6 KiB
Markdown
112 lines
4.6 KiB
Markdown
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# Introduction
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CryptCheck is a Ruby toolbox that help anybody to check for cryptography security
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level and best practices compliance.
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CryptCheck is released under
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[AGPLv3+](https://www.gnu.org/licenses/agpl-3.0.en.html) license.
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# Preliminary warning
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**/!\ This tool use custom weak builds of OpenSSL library and OpenSSL Ruby extension /!\**.
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Those builds are cryptographically weaken to be able to test for (very) weak and
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today totally deprecated ciphers.
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Don’t deploy it on production machine to avoid any security troubles, or use VM
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to isolate them !
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# Setup
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## Ruby
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You need a fully operationnal Ruby stack.
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Because of the warning above, don’t use your system Ruby.
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I recommend to use [RBEnv](https://github.com/sstephenson/rbenv) and it
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[Ruby-build](https://github.com/sstephenson/ruby-build) plugin to build a new
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ruby environment instead of your system one.
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Currently supported Ruby stack is v2.2.2.
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## OpenSSL library and Ruby extension
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To be able to test for (very) weak ciphers and to have access to DH parameters,
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CryptCheck need custom build of OpenSSL library and patched build of OpenSSL Ruby
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extension.
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Once you have cloned CryptCheck repository, just run `make` inside to
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build the needed libraries.
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If `make` fails with the following error :
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```
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make: *** No rule to make target 'lib/libssl.so.1.0.0', needed by 'libs'. Stop.
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```
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just run again `make` (if you understand this problem, contact me !).
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The built libraries (*libcrypto.so*, *libssl.so* and *openssl.so*) are located
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under the *lib* directory.<br/>
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CryptCheck use *LD_LIBRARY_PATH* and Ruby load path hack to inject those weaken
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libraries instead of the system ones.
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## Ruby dependencies
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CryptCheck relies on few Ruby libraries, managed with [Bundler](http://bundler.io/).
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To fetch and install them, just run `bundle install`.
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# Usage
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Simply run the corresponding runner of what you want to test :
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* HTTPS : ```bin/check_https example.org```
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* XMPP : ```bin/check_xmpp example.org```
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* SMTP : ```bin/check_smtp example.org```
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If you want more information of what is going on under the hood, run the command
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with debug enabled, like ```bin/check_https example.org debug```
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## Understanding results
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Rank goes from "A+" (perfect) to "F" (very weak).<br/>
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"M" means your certificate and your hostname mismatch.<br/>
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"T" means your certificate is not issued by a valid root certificate authority.
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Only a perfect setup gets a perfect score and a "A" rank :).<br/>
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"A" score is based on [RFC 7525](https://tools.ietf.org/html/rfc7525) recommandations.
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* Protocol
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* SSL (v2 and v3) are totally [deprecated](https://tools.ietf.org/html/rfc7568)
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now, because of very serious known vulnerabilities
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([Poodle](https://www.openssl.org/~bodo/ssl-poodle.pdf)…).
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Using one of them cap your rank to "F".
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* TLSv1 and TLSv1.1 suffer of the
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[Poodle TLS](https://community.qualys.com/blogs/securitylabs/2014/12/08/poodle-bites-tls)
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vulnerability.
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* TLSv1.2 is the only remaining protocol with no known vulnerabilities, so if
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you don’t support it, your rank is cap to "B".
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* Key size
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* If you use certificate key less than 2048 bits, your rank is cap to "B".
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* Ciphers
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* Very weak ciphers, including MD5 hash, anonymous DH parameters, NULL ciphers
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(yes, it exits…), export ciphers ([Freak](https://freakattack.com/)) or weak
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ciphers (RC4, DES…) cap your rank to "F".
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* 3DES is considered weak and must be avoided, using it cap your score to "C".
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* Score
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* Protocol score is based on the **weakest** protocol you support :<br/>
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SSLv2 = 0, SSLv3 = 20, TLSv1 = 60, TLSv1.1 = 80, TLSv1.2 = 100.
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* Key score is based on your certificate key size :<br/>
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<512 = 10, <1024 = 20, <2048 = 50, <4096 = 90, ≥4096 = 100.
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* Cipher score is based on the **weakest** cipher you support :<br/>
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0 = 0, <112 = 10, <128 = 50, <256 = 90, ≥256 = 100.
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* Overall score is based on the other scores :<br/>
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overall = 0.3 * protocol + 0.3 * key + 0.4 * cipher
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* Best practices
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* PFS : you gain this flag when you support **only**
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[perfect forward secrecy](https://en.wikipedia.org/wiki/Forward_secrecy)
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ciphers (DHE or ECDHE)
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* HSTS : you gain this flag when you protect yourself with
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[HTTP Strict Transport Security](https://tools.ietf.org/html/rfc6797).
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* Long HSTS : you gain this flag when you support HSTS with a duration of at
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least 6 monthes.
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* Rank
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* Rank is based on your overall score and above caps :<br/>
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<20 = F, <35 = E, <50 = D, <65 = C, <80 = B, ≥80 = A.
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* If you get an "A" and you have all the best practices above, you get "A+".
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