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Shiny, Let’s Be Bad Guys: Exploiting and Mitigating the Top 10 Web App Vulnerabilities

Shiny, Let’s Be Bad Guys: Exploiting and Mitigating the Top 10 Web App Vulnerabilities






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    Shiny, Let’s Be Bad Guys: Exploiting and Mitigating the Top 10 Web App Vulnerabilities Shiny, Let’s Be Bad Guys: Exploiting and Mitigating the Top 10 Web App Vulnerabilities Presentation Transcript

    • Shiny,Let’s Be Bad Guys! Exploiting and Mitigating the Top 1 Web App Vulnerabilities 0 Mike Pirnat - @mpirnat David Stanek - @dstanek Text
    • Announcements
    • Schedule & Lunch• This session will run 9:00 AM - 12:20 PM• 20-minute break at 10:50 AM• Lunch 12:20 PM - 1:20 PM• Lunch moved to Exhibit Hall D
    • Volunteering Opportunities• Low-commitment! Fun!• SWAG bagging: Thursday 4-8 PM • Just do 10 bags! (~1/2 hr)• Registration Desk: any time • 1-2 hours helps • Friday => meet everyone!
    • Volunteering Info• Current needs: http://bit.ly/pycon-volunteering-status• More information: http://bit.ly/pycon2013-volunteer
    • Tutorial Feedback• Go here: • https://www.surveymonkey.com/s/ pycon2013_tutorials or • https://goo.gl/PvHDc• Be honest!
    • http://i.qkme.me/3r16r5.jpg
    • QWho here hasvulnerable apps?
    • Why it Matters• Your users• Your data• Your business
    • OWASP• http://www.owasp.org• Open Web Application Security Project• Non-profit focused on improving software security• Documentation and tools to help learn about security and protect your apps
    • OWASP Top Ten• Based on risk data from 8 firms• Over 500,000 vulnerabilities, hundreds of orgs, thousands of apps• Selected & prioritized by prevalence data combined with estimates of exploitability, detectability, and impact• Recently updated for 2013!
    • Today• Background on a type of vulnerability• Exploit it!• Discuss prevention• Django-specific advice where possible
    • Disclaimer
    • Setup: 1Make a virtualenv:$ virtualenv badguys$ cd badguys$ source bin/activate
    • Setup: 2Clone our repository:$ git clone https://github.com/mpirnat/lets-be-bad-guys srcOr pull the latest changes:$ cd src$ git pull
    • Setup: 3Install dependencies:$ cd src$ pip install -r requirements.txt
    • Setup: 2 & 3 (Offline/USB)• Extract the project: $ mkdir src $ unzip /Volumes/BADGUYS/project/ badguys.zip -d src/• Install dependencies: $ cd src $ pip install -r requirements.txt -i file:///Volumes/BADGUYS/software
    • Setup: 4Start up the app:$ python manage.py runserver
    • Find a Partner
    • 1Injection
    • Injection Attacks• When an application sends untrusted data to an interpreter• Can result in data loss/corruption, lack of accountability, denial of access• Can lead to complete host takeover
    • Trust No One• External users• Internal users• Administrators
    • Attack Vectors• GET parameters• POST parameters• PATH_INFO• Some HTTP headers: Cookie, Host• Uploaded Files
    • Possible Consequences• Creation of malicious SQL (or other queries)• Accessing private files on disk• Arbitrary code execution
    • Real-World Examples• Sony Playstation Network• Ruby on Rails• http://es.pn/Z0jnoi
    • SQL Injection• Unescaped user input causes the premature end of a SQL query and allows a malicious query to be executed... """ select * from users where username=%s; """• http://localhost:8000/injection/sql
    • Accessing Private Files• File system access + unvalidated user input allows attackers to navigate the file system• http://localhost:8000/injection/file- access
    • Arbitrary Code Execution• Unsafe input is dynamically evaluated or executed• http://localhost:8000/injection/code- execution
    • Prevention• Validate ALL user input• Sign cookies, don’t accept if signature is bogus/missing• Use ORMs or bind variables when talking to the database• Don’t use eval or exec, beware of pickle, user-supplied YAML, etc.
    • Django Advice• Make sure data types for your model are tight• Use Forms instead of ModelForms for stronger validation• Make new validators as needed for your application• Make sure your URL regexes for dynamic URLs are tight
    • Django Advice• Use the ORM when you can• When you can’t, use extreme caution!• Bind variables• No string concatenation/formatting of anything that came from the client
    • 2 BrokenAuthentication & Session Management
    • Broken Auth & Session Management• Attacker uses leaks or flaws in authentication or session management to impersonate users• Roll-your-own solutions contribute to the difficulty of finding these flaws
    • Possible Consequences• Compromised user accounts• Compromised administrative accounts• Unauthorized use of privileged functionality
    • Prevention• Hash or encrypt passwords• Don’t let credentials be easily overwritten• Don’t put session IDs in URLs• Allow session IDs to timeout/log out• Rotate session IDs after successful login• TLS connections for passwords, session IDs
    • Django Advice• Use django.contrib.auth• Consider https://github.com/yourlabs/ django-session-security middleware for timing out sessions• We’ll talk about transport layer security later on...
    • 3 Cross-SiteScripting (XSS)
    • XSS Attacks• Cross-Site Scripting (XSS)• The most prevalent web app security flaw• App includes user-supplied data in content sent to the browser without properly validating or sanitizing it
    • XSS Attacks• Stored: injected code permanently stored in database, message forum, comment, etc.• Reflected: injected code in live request to server, reflected back in error message or search result• DOM: injected code in browser DOM environment that causes scripts to run in unexpected ways (eg, reading from URL)
    • Possible Consequences• Execute scripts in a victim’s browser• Hijack sessions• Deface sites• Insert hostile content• Redirect users• Hijack browser (install malware)
    • Most Often Seen...• Places where user-created text is displayed to other users (comments, messages)• Form inputs where value is populated with user-supplied data• Script tags where user-supplied data is populated into script variables
    • XSS in Dynamic URLs• Part of the URL path is variable, isn’t validated, and gets included into the page• http://localhost:8000/cross-site- scripting/path-matching/your-path- here
    • XSS in QueryString Parameters• Unvalidated user input from a query string parameter is included in the page• http://localhost:8000/cross-site- scripting/query-params?qs=awesome
    • XSS in Form Fields• The value part of an input is prematurely terminated, allowing Javascript to be injected into the element (eg, adding an onclick)• http://localhost:8000/cross-site- scripting/form-field
    • QCan you trust the database?
    • Prevention• Escape all untrusted data based on the HTML context the data will be placed into• Whitelist input validation• Consider auto-sanitization libraries for rich content (eg, OWASP’s AntiSamy)• Update your parents’/in-laws’ browsers!
    • Django Advice• Be careful with the safe filter, django.utils.safestring, etc.• Be careful with your own template tags; django.utils.html.escape is your friend!• Use form.as_p, form.as_table, form.as_ul
    • 4 InsecureDirect Object References
    • Insecure DirectObject Reference• Expose a reference to an internal implementation object without verifying authorization• Attacker changes URL or GET/POST parameters, cookies
    • Possible Consequences• Compromise of all data that can be referenced by the vulnerable parameter• Unless the namespace is sparse, an attacker can easily access all available data of that type
    • Exercises• Manipulate parameters in the URL to access data that doesn’t belong to you• http://localhost:8000/direct-object- references
    • Prevention• Implement access controls on any direct references to restricted resources• Implement per-user or per-session indirect object references
    • Django Advice• Use permissions architecture to lock down views• Customize queryset for looking up objects that involve user ownership
    • 5 SecurityMisconfiguration
    • Security Misconfiguration• Insecure application settings• Unpatched flaws• Unused pages
    • Possible Consequences• Unauthorized access to some system data or functionality• Potential complete system compromise
    • Exercises• Demos and discussion• http://localhost:8000/misconfiguration
    • Prevention• Have a repeatable hardening process• Have a process for keeping on top of updates and patches• Architecture that provides secure separation between components• Periodic scans and audits
    • Django Advice• Don’t run in debug mode in production• Keep your SECRET_KEY secret!• Keep Python code out of webserver’s root• Don’t run admin publicly (if you can help it)• Don’t use the built-in admin for normal user admin tasks
    • QGateway to Social Engineering?
    • 6 SensitiveData Exposure
    • Sensitive Data Exposure• Failure to properly protect credit cards, tax ids, authentication credentials, etc.• Sensitive data deserves extra protection such as encryption at rest or in transit, special precautions when exchanged with the browser
    • Insecure Cryptographic Storage• Not encrypting worthy data• Unsafe key generation & storage, failure to rotate keys• Weak algorithms• Weak or unsalted hashes
    • Insufficient Transport Layer Protection• May not authenticate, encrypt, and protect the confidentiality and integrity of sensitive network traffic• May use weak algorithms• May use expired or invalid certificates• May use certificates incorrectly
    • Possible Consequences• Compromise of all data that should have been encrypted• This can be highly sensitive information: credentials, credit cards, personal data, health records, etc.
    • Possible Consequences• Expose individual users’ data• Account theft• Compromise an admin account?!• Poor SSL setup can facilitate phishing and man-in-the-middle attacks
    • Attack Vectors• Attacker monitors network traffic of your users• Maybe in public places (Starbucks, conference wi-fi, etc.)• Maybe back end connections• Maybe inside your network (!!!)
    • Prevention• Encrypt sensitive data at rest• Encrypt offsite backups; manage keys separately• Use strong standard algorithms, strong keys• Hash passwords with strong standard algorithm & use appropriate salt• Protect passwords & keys from unauthorized access
    • Prevention• Require SSL for all sensitive pages; redirect non-SSL requests to SSL• Set the “secure” flag on sensitive cookies• Use only strong SSL algorithms• Ensure your cert is valid, not expired, not revoked, and matches your domain• SSL/encryption on the back end too
    • Django Advice• Use django.contrib.auth for proper password salting and hashing• Require SSL in Apache or Nginx• Require SSL using middleware: • http://www.redrobotstudios.com/blog/2010/02/06/ requiring-https-for-certain-paths-in-django/ • http://djangosnippets.org/snippets/2833/ • http://djangosnippets.org/snippets/1467/
    • 7 Missing Function LevelAccess Control
    • Missing Function Level Access Control• Application doesn’t protect its functions properly• Misconfiguration• Forgot proper code checks
    • Attack Vectors• Authorized user changes a URL or parameter to a privileged function• Anonymous users could access private functions that aren’t protected
    • Possible Consequences• Compromised user accounts• Compromised administrative accounts• Unauthorized use of privileged functionality
    • Exercises• Manipulate the URL to access privileged functionality• http://localhost:8000/missing-access- control
    • Prevention• Consider every page; public or private?• If authentication is required, make sure that checks are in place• If additional authorization is required, make sure that checks are in place• Deny all by default; explicitly grant access to users or roles
    • Django Advice• Use the permissions architecture to lock down views• Don’t use the built-in admin for normal user admin tasks
    • 8 Cross-SiteRequest Forgery
    • CSRF Attacks• Cross-Site Request Forgery (CSRF)• Attacker tricks victim into submitting forged HTTP requests• Attack succeeds if user is authorized/ authenticated
    • Attack Vectors• Image tags• Cross-Site Scripting (XSS)• Fake buttons• Phishing forms• Other techniques
    • Possible Consequences• Cause victim to change any data the victim is allowed to change• Cause victim to perform any function the victim is authorized to use• Impact varies based on victim’s role• Think of some possibilities...
    • Real-World Examples• Facebook: http://amolnaik4.blogspot.com/ 2012/08/facebook-csrf-worth- usd-5000.html• Google/Gmail: http://cryptogasm.com/2012/02/does- google-understand-csrf/
    • CSRF via Image• Craft an “image” link that triggers some site functionality• http://localhost:8000/csrf/image
    • What if...<img src="http://example.com/transferFunds?amount=1500&destinationAccount=attackersAcct#"width="0" height="0" />
    • CSRF via Form Post• Create an innocuous-looking form that POSTs to a vulnerable location• http://localhost:8000/csrf/third-party- site
    • Prevention• Don’t “do” things on a GET• Include a unique token in a hidden field (often used in concert with a cookie)• Validate token to make sure the request is from on-site• Avoid putting the token into a query string
    • Django Advice• Don’t change the built-in settings!• Do use the CSRF middleware and template tag in forms• Be VERY CAREFUL about deactivating it (csrf_exempt decorator)• Be careful about APIs (Tastypie, oauth)
    • 9Using Known VulnerableComponents
    • Components with Known Vulnerabilities• Libraries, frameworks, and other modules almost always run with full privilege• Hard to stay up to date on everything• Do you even know all the components in use, let alone their versions?• Components with known problems can be identified & exploited with automated tools
    • Attack Vectors• Attacker identifies a weak component through scanning or manual analysis• Customize exploit as needed• More difficult the deeper the component is in the application
    • Possible Consequences• Full range of weaknesses are possible• Impact could be minimal, or...• Complete host takeover!• Data compromise!
    • Prevention• Don’t use components you don’t write (unrealistic)• Keep components up to date• Identify all components and versions• Monitor security of these components
    • Django AdviceWhen @jacobian says there are newsecurity releases for Django, upgrade!
    • 10UnvalidatedRedirects & Forwards
    • Redirection Abuse• Attacker tricks user into visiting a URL that redirects or forwards the request without validating the redirect location• Users prone to click because the link is to a legitimate site
    • Possible Consequences• Install malware• Phishing/information disclosure• Bypass access controls
    • External Redirection• Use a redirection URL to redirect to an external location• http://localhost:8000/redirects-and- forwards/redirects
    • Forwards• Manipulate a forward parameter to gain access to privileged functionality• http://localhost:8000/redirects-and- forwards/forwards
    • Prevention• Don’t use redirects or forwards• Don’t involve user-supplied data to build the redirect location• Ensure the supplied value is valid and authorized for the user
    • Django Advice• Use django.utils.http.is_safe_url to check redirect URLs• Used by django.contrib.auth internally• Consider wrapping is_safe_url if you have to allow other off-domain URLs
    • QWho here hasvulnerable apps?
    • Parting Thoughts
    • Think Likea Bad Guy
    • Don’t Stop at Ten
    • Constant Change
    • Think Positive
    • Announcements• Lunch—moved to Exhibit Hall D• Feedback—https://goo.gl/PvHDc• Volunteer: http://bit.ly/pycon2013-volunteer http://bit.ly/pycon-volunteering-status
    • Links• http://www.owasp.org• https://www.owasp.org/index.php/ Category:OWASP_Top_Ten_Project• https://docs.djangoproject.com/en/dev/ topics/security/• https://github.com/mpirnat/lets-be-bad-guys
    • Contact UsMike Pirnathttp://mike.pirnat.com@mpirnatDavid Stanekhttp://traceback.org@dstanek