Introduction to Web Application Security Rex Booth, CISSP, PMP Senior Manager, Grant Thornton LLP

Introduction: Rex Booth Senior Manager at Grant Thornton 10+ years of IT experience Former web application developer Leads cybersecurity group for Grant Thornton's public sector practice Experience with information security from a variety of perspectives including developer, auditor, and ISSO

Agenda Why target web applications? Web application attack surface overview Attack examples Client layer attacks Application layer attacks Data layer attacks 3rd party trust attacks Live Demonstration Best Practices and Remediation resources Questions

Why target web applications? Incentives Valuable targets Financial Competitive advantage (corporate or national) Force multiplier Reputation / Prestige Absence of effective deterrents Soft targets: Weak or poorly implemented security Low cost of entry: cheap and easy access “Wild West” mentality regarding probability of detection, capture and punishment

Agenda Why target web applications? Web application attack surface overview Attack examples Client layer attacks Application layer attacks Data layer attacks 3rd party trust attacks Live Demonstration Best Practices and Remediation resources Questions

Web application attack surface 3rd Party Trusts Client layer: HTML, JavaScript, Flash, etc Application layer: Business logic (.Net, Java, etc) Data layer: Access components, RDBMS Client layer: Code and functionality executed on the client-side Various vulnerabilities Two key points: Never trust client-supplied data Don’t introduce vulnerabilities by trying to offload cycles from the server to the client

Web application attack surface 3rd Party Trusts Client layer: HTML, JavaScript, Flash, etc Application layer: Business logic (.Net, Java, etc) Data layer: Access components, RDBMS Application layer: Expression and capture of business rules and business policy logic in code; Workflows based on the ordered tasks of passing documents or data from one participant (a person or a software system) to another; Do those expressions introduce vulnerabilities? Attacks on specific technology and poor implementation

Web application attack surface 3rd Party Trusts Client layer: HTML, JavaScript, Flash, etc Application layer: Business logic (.Net, Java, etc) Data layer: Access components, RDBMS Data layer: Likely the most valuable component of your application to your organization Less focused on code and logic, more focused on good implementation and maintenance, proper technology

Web application attack surface 3rd Party Trusts Client layer: HTML, JavaScript, Flash, etc Application layer: Business logic (.Net, Java, etc) Data layer: Access components, RDBMS 3rd Party Trusts: Critical to maintain awareness of system interactions Federal Sector C&A Interconnection Agreements Potential to affect all layers of the application Repeat the attack surfaces at the client, application and data layers for each 3rd party trust

Agenda Why target web applications? Web application attack surface overview Attack examples Client layer attacks Application layer attacks Data layer attacks 3rd party trust attacks Live Demonstration Best Practices and Remediation resources Questions

Injection Attacks SQL injection is the most common web attack An attacker inserts commands that are used to dynamically construct SQL queries Attacker may be able to view or modify any data in a database Severity can be equivalent to a full database compromise Other injections include XML, LDAP, code injection, remote file inclusions Any action that takes input from the user and uses it in a query or function

SQL Injection Scenario You wish to edit your credit card number in your account profile on http://www.shoppingsite.com To verify your identity, the site asks for the last 4 digits of your credit card The application then passes your input to the following query SELECT * FROM credit_cards WHERE digits = ‘your_input’

SQL Injection Scenario What if the attacker enters 1234’ OR ‘1’ = ‘1 The full query then becomes SELECT * FROM credit_cards WHERE digits = ‘1234’ OR ‘1’ = ‘1’; This query will always return true and, therefore, will return every card in the database.

Cross Site Scripting (XSS) Affects the client web browser. Scripting code from URL or HTML Form gets rendered in the page sent by the server. 2 types of XSS Persistent / Stored: attack code gets stored in the application data store and affects all users who visit the page. Non-Persistent / Reflected: attack code does not get stored and can only affect 1 user at a time. One of the most prolific and dangerous vulnerabilities on the web.

Cross Site Scripting (XSS) Scenario What if we change “shawn” to: “><script>alert(document.cookie)</script>

Cross Site Scripting (XSS) Scenario

Cross Site Request Forgery (CSRF) Affects the client browser. The vulnerability allows an attacker to force the browser to fraudulently execute application functionality. Leverages the user’s authenticated session on the target application. Not *really* a vulnerability, rather an exploit of expected functionality.

Authentication and Authorization Lack of authentication / authorization. Unauthorized data access. Unauthorized system functionality access. Predictable session identifiers. Session Fixation. Session Replay. Brute forcing of credentials.

Session Fixation Example Session Fixation occurs when a session identifier is not refreshed after successful authentication The following sequence describes an application vulnerable to Session Fixation: When a user browses to www.whatever.com, they receive Cookie: my_cookie=abcdefg After logging in, the application elevates my_cookie=abcdefg from unauthenticated to authenticated status Why is this a problem? The initial value may have been sent over an unencrypted channel Attacker could use XSS to set a known value in the target browser The application may accept any value prior to authentication, making this even easier for an attacker

Business Logic Flaws Flaw in the design and/or implementation of the project design. Booking a ticket on a web application without paying. Registering an account without completing all required steps. Apply the same coupon/discount multiple times on the same order. Account lockout on auction sites. Setting your own pricing on a product. No way to detect this type of vulnerability using automated tools.

Host and 3rd Party Code Keeping up with patches Patch management 3rd party code dependency updates Host security Unused network services Password Policy Brute forcing Logging Hidden/Old/Unreferenced files Building a good relationship with SysAdmins

Agenda Why target web applications? Web application attack surface overview Attack examples Client layer attacks Application layer attacks Data layer attacks 3rd party trust attacks Live Demonstration Best Practices and Remediation resources Questions

Agenda Why target web applications? Web application attack surface overview Attack examples Client layer attacks Application layer attacks Data layer attacks 3rd party trust attacks Live Demonstration Best Practices and Remediation resources Questions

Best Practices Summary Input validation and output encoding Strong authentication and password management Effective access controls Safe error handling and meaningful logging Protection of data at rest and in motion Proper system and database configuration See the OWASP Secure Coding Practices Quick Reference Guide for more information

Remediation Resources Incorporating security into the SDLC https://buildsecurityin.us-cert.gov http://www.owasp.org http://www.webappsec.org/ Post-deployment remediation Two basic approaches: fix the underlying problem or get in between the threat and the asset The latter, including web application firewalls, are not a panacea, but can be useful

Questions Ask now or contact via email: Rex.Booth@us.gt.com