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Securing Your Rails App Mike Nicholaides @nicholaides promptworks.com

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http://promptworks.com! @promptworks

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http://xkcd.com/327/

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Security

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Security is hard

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Seriously. It’s really hard.

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Are we secure?

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Awareness

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Know your risks • data • system • network • identity

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Know your environment •server •network •hardware

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Know your perimeter •ops architecture •libraries & services

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Security Strategy

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Minimize risks Security Strategy

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Visibility Security Strategy

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Audit Logs •key transactions •blocked access attempts •append-only logs

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Alerting •business anomalies •usage anomalies

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Have a plan Security Strategy

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Security as part of the process Security Strategy

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That’s great, but what about my Rails app?

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Users can submit arbitrary input Fundamental Security Problem:

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POST /users HTTP/1.1 Host: innocent-corporation.com Content-Type: application/json Content-Length: 26 ! { "user": { "name": "Joe Hacker", "admin": true } }

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Don’t trust user input

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• params • cookies • request headers • url path • incoming emails • uploaded ﬁles • input from other services • scraped from the web Don’t trust user input

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Blacklisting

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Blacklisting: Good class Account < ActiveRecord::Base validates :subdomain, exclusion: { in: ['www', 'mail'] } end

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Blacklisting: Good “WWW” “ www” “” “wwww”

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Blacklisting: Bad blacklist = /SELECT|INSERT|UPDATE|DELETE/ ! name = params[:name].gsub(blacklist, '') ! Account.where("name = #{name}")

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Blacklisting: Bad select selSELECTect SELECT/**/id FROM ... TRUNCATE, DROP, ALTER

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Blacklisting •occasionally effective •must know ALL bad inputs

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Whitelisting

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Whitelisting class User property :admin, Boolean property :name, String property :address, String ! attr_accessible :name, :address end

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Whitelisting •most effective •least ﬂexible

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Sanitization <%= sanitize(@user.bio) %>

About Me

I'm a resourceful developer

About Me

performXSS();

I'm a resourceful developer

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DON’T ROLL YOUR OWN

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1756

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Sanitization •effective, but hard •don’t roll your own

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Safe Data Handling becomes performXSS(); <script> performXSS(); </script>

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Safe Data Handling becomes 'N Sync WHERE band = '\'N Sync'

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Safe Data Handling /songs?band=Mary%20Kate%20%26%20Ashley becomes Mary Kate & Ashley

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Safe Data Handling • super effective • don’t roll your own (if you can help it)

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Semantic Checks if current_user.owns? account if account.balance > 0

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Handling User Input • Blacklist • Whitelist • Sanitization • Safe data handling • Semantic checks

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Recommendations

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Learn

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Rails Security Guide

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Code Review

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Code Review • Trace user-controllable data • Signatures of common vulnerabilities • review risky code

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Brakeman

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Lean on the community

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The Ruby Toolbox

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Don’t roll your own •sanitization •escaping/encoding •authentication •cryptography

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Devise

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http://www.schneierfacts.com

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http://www.schneierfacts.com

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Use Rails

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Keep Rails up-to-date

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Ruby on Rails: Security

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Keep gems up-to-date

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bundle outdated Outdated gems included in the bundle: * awesome_print (1.2.0 > 1.1.0) * axiom-types (0.0.5 > 0.0.4) * builder (3.2.2 > 3.1.4) * cliver (0.3.1 > 0.2.2) * coderay (1.1.0 > 1.0.9) * database_cleaner (1.2.0 > 1.0.1) * descendants_tracker (0.0.3 > 0.0.1) * guard (2.0.3 > 1.8.3) * guard-rubocop (1.0.0 > 0.2.2) * haml_coffee_assets (1.14.1 > 1.14.0) ...

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bundler-audit Name: actionpack Version: 3.2.10 Advisory: OSVDB-91452 Criticality: Medium URL: http://www.osvdb.org/show/osvdb/91452 Title: XSS vulnerability in sanitize_css in Action Pack Solution: upgrade to ~> 2.3.18, ~> 3.1.12, >= 3.2.13 ! Name: actionpack Version: 3.2.10 Advisory: OSVDB-91454 Criticality: Medium URL: http://osvdb.org/show/osvdb/91454 Title: XSS Vulnerability in the `sanitize` helper of Ruby on Rails Solution: upgrade to ~> 2.3.18, ~> 3.1.12, >= 3.2.13

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Keep your code clean

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http://agileinaﬂash.blogspot.com/

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Regression tests for vulnerabilities

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Outside security audit

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Security is hard

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http://xkcd.com/538/

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@nicholaides mike@promptworks.com