Security Checklist

Adapted from SecurityChecklist.org | Hacker News Discussion

Instructions

• Create a Github Gist from the README for the project you are auditing to enable the clicking checkboxes as you perform each operation.
• When creating the Gist replace example.com with the domain you are auditing.

Checklist

• Is the website only served over https?

$ curl -s -I http://example.org | grep '^HTTP'
HTTP/1.1 301 Moved Permanently
$ curl -s -I https://example.org | grep '^HTTP'
HTTP/1.1 200 OK

• Is the HSTS http-header set?

$ curl -s -I https://example.org | grep '^Strict'
Strict-Transport-Security: max-age=63072000; includeSubdomains; always

• Is the server certificate at least 2048 bits?

$ openssl s_client -showcerts -connect example.org:443 |& grep '^Server public key'
Server public key is 2048 bit

• Is TLS1.2 the only supported protocol?

$ curl --sslv3 https://example.org
curl: (35) Server aborted the SSL handshake
$ curl --tlsv1.0 -I https://example.org
curl: (35) Server aborted the SSL handshake
$ curl --tlsv1.1 -I https://example.org
curl: (35) Server aborted the SSL handshake
$ curl --tlsv1.2 -s -I https://example.org | grep 'HTTP'
HTTP/1.1 200 OK

• Do all supported symmetric ciphers use at least 256 bit keys?

$ nmap --script ssl-enum-ciphers -p 443 example.org
PORT    STATE SERVICE
443/tcp open  https
| ssl-enum-ciphers:
|   TLSv1.2:
|     ciphers:
|       TLS_DHE_RSA_WITH_AES_256_CBC_SHA - strong
|       TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 - strong
|       TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 - strong
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA - strong
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 - strong
|       TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 - strong
|     compressors:
|       NULL
|_  least strength: strong              

• Is the Diffie-Hellman prime at least 4096 bits?

$ openssl s_client -connect example.com:443 -cipher "EDH" |& grep "^Server Temp Key"
Server Temp Key: DH, 4096 bits

• Have you ensured that your content cannot be embedded in a frame on another website?

$ curl -s -I https://example.org | grep '^X-Frame-Options'
X-Frame-Options: SAMEORIGIN
$ curl -s -I https://example_2.org | grep '^X-Frame-Options'
X-Frame-Options: DENY # Also acceptable

• Have you ensured that the Internet Explorer content sniffer is disabled?

$ curl -s -I https://example.org | grep '^X-Content'
X-Content-Type-Options: nosniff

• Do all assets delivered via a content delivery network include subresource integrity hashes?

<link
  rel="stylesheet"
  href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.2/css/bootstrap.min.css"
  integrity="sha384-y3tfxAZXuh4HwSYylfB+J125MxIs6mR5FOHamPBG064zB+AFeWH94NdvaCBm8qnd"
  crossorigin="anonymous"
>

• Are password checks done during user sign-up, to ensure minimum length passwords of at least 8 characters. Consider checking password entropy using strong_password?

• Are you storing only the hash of your users password, and not the cleartext password, using (say) BCrypt?

• Are failed login attempts throttled and IP addresses banned after a number of unsuccessful attempts, using (say) Rack::Attack?

• Are you only allowing ssh login attempts via VPN or using fail2ban to throttle ssh login attempts?

sudo fail2ban-client status sshd

• Have you disabled password-based login over ssh, and only allowed key-based login?

$ cat /etc/ssh/sshd_config  | grep '^Password'
PasswordAuthentication no

• Do session cookies have the 'Secure' and 'HttpOnly' flag set?

$ curl -s -I example.com/url_that_sets_cookie | grep '^Set-Cookie'
Set-Cookie: ****;Path=/;Expires=Fri, 16-Mar-2018 19:18:51 GMT;Secure;HttpOnly;Priority=HIGH

• Do forms prevent cross-site request forgery using a hidden field?

$ curl -s https://example.com/url_with_form | grep csrf
<meta name="csrf-param" content="authenticity_token" />
<meta name="csrf-token" content="+Y18jUBDT3eaxb+qrAk/TebfzybOyxShFwspkdgVw2eym0LE8b6TCJ8l6kXSUv5Mv772VpnvQ7G0VSigK4Ez1w==" />

$ curl -s https://example.com/url_with_form | grep hidden | grep authenticity_token
<input type="hidden" name="authenticity_token" value="8FKbxvZoUIc1lUUK5BFpxvX15ZjETB5z2zuevU+4+TOQvg3kdLG+5RU0O4LeNL0rM4hultbMXAIA0UXtAadxLA==" />

• Are all user uploads validated for expected content type?

• Are the permissions of all uploaded files readonly?

• Are all form fields validated, either with regex where applicable or at a least to prevent excessively large input?

Example, name fields must be less than 250 characters to prevent pasting a novel into the field.

• Are there unit tests (say, using Capybara) which show that one authenticated user cannot access another user's content?

• Have you made sure that database passwords, server signing keys, and hash salts are not checked into source control?

• Have you reviewed your account recovery flow to ensure this doesn't invalidate everything completed on this checklist?