Copyright © The OWASP Foundation Permission is granted to copy, distribute and/or modify this document under the terms of the Creative Commons Attribution-ShareAlike 2.5 License. To view this license, visit The OWASP Foundation OWASP AppSec Seattle Oct Advanced Web Services Security & Hacking Justin Derry, OWASP Brisbane Chapter Leader Practice Leader, b-sec Consulting

OWASP AppSec Seattle Presentation Agenda  Web Services & Technology  What is a Web Service  Where are they commonly used & why  Are you Exposing yourself (Willingly/Unwillingly?)  What’s happening right now.  An Attackers Toolkit  Known common attacks against XML  XML Interceptor Toolkit  Case Studies (XML Web Service & WS-Security Web Service)  Web Services Security  WS-Security  Web Services Appliances (What they can/can’t do)  Common Mistakes and pitfalls

OWASP AppSec Seattle What is a Web Service?  Many things could be called a Web Service.  For this presentation we are talking about… “A Web Service is a system designed to support interoperable communication from machine to machine over a network. It includes an interface described in a machine-processable format (WSDL), and is typically conveyed using HTTP with XML serialization.”

OWASP AppSec Seattle XML Web Service Communication  Typical Web Service Communication Packet

OWASP AppSec Seattle Common Application Uses  Public Web Applications  AJAX (maps.google.com, mp3act.net)  Application API’s Google, Yahoo, Ebay, Flickr, Amazon, IMDB, etc.  Internet Payment Hubs (Most major banks use XML Web Services for Credit Card Processing, or similar XML Technology)  Business B2B Communication Gateways  Extends the business outside their internal network  Communicate easily with third parties (trusted or un- trusted)

OWASP AppSec Seattle Are you exposing yourself?  Vendor Applications  In-house applications that share data with partners  Developers writing a tool to solve a problem without business awareness  New Technologies (AJAX, Web 2.0, Google)  Maybe not called a Web Service but has similar characteristics to an XML Web Service

OWASP AppSec Seattle Known Common Web Service Attacks  Parsing Exploits  SAX/DOM Known Common Exploits on Vendor Frameworks  Custom parsers that are poorly written  XML Injection (Passed into XML Stream)  XPath Injection Attacks  XML Manipulation (i.e. CDATA Manipulation etc.)  WSDL Discovery and Manipulation with schemas  DoS attacks against Web Services  Typical HTTP/S Style Header Injection attacks  Common Application Attacks (SQL Injection etc.)

OWASP AppSec Seattle Vulnerability Breakdown (Real-world) source: b-sec Application Reviews

OWASP AppSec Seattle Increasing Attacks & Web Services  Increasing use of Web Service technology  Vendors are using to rapidly deploy applications and services  Research into exploits is increasing  It’s a “Cool & New” technology we should use it “Today over 70% of attacks against a company's Web site or Web application come at the 'Application Layer' not the Network or System layer” (Gartner Group)

OWASP AppSec Seattle XML Interceptor Toolkit (1.0)  Windows Forms.NET Toolkit (vb.net 2.0)  Developed in Australia  Currently in initial release for OWASP Seattle 06  Work in Progress – Do you want to get involved?

OWASP AppSec Seattle Web Interceptor Features  Currently in initial release for OWASP Seattle 06  Supports XML TCP Capture as Proxy (initial)  Allows replay/manipulation of XML POST requests  Easy interface to inject and force header changes  Support for some automated attacks  Saving and recording of attack history  Perform most XML related attacks through the tool  Includes basic security functions (Base64/MD5/SHA)  Support for SSL to be available shortly (Oct/Nov)  Support for HTTP/S Injection and Proxy tool as well (Oct/Nov)

OWASP AppSec Seattle Web Interceptor – Demo & Download  Demo initial features available in Release 1.0 of Interceptor Toolkit (XML Interception & Replay)  Download available at

OWASP AppSec Seattle Case Study (XML Web Service)  Windows Forms.NET Client (Demo shows interface)  Remotely deployed to Call Center/Support  Connected over Public Internet to Application  Basic XML Web Services used (.NET Framework without WS-* or additional controls)

OWASP AppSec Seattle Exploiting a Web Service through XML  Performing SQL Injection attacks using an XML message and the Interceptor Toolkit.  How to use CDATA in XML Fields to pass Cross Site Scripting..  How we did it (Web Interceptor Example)

OWASP AppSec Seattle Case Study Risks Identified  Assumed No Interface – No Attacks  No Data Validation (most OWASP Top Ten Missing)  Serious SQL Injection & XSS Flaws  Passed through XML to Web Interface  XML Not encrypted (Replay/Data Interception)  Returned Error Messages in XML

OWASP AppSec Seattle Case Study (WS-Security Enabled Service)  Financial Institution (i.e. Bank)  Transactional Gateway Solution for their clients  Credit Card Processing/Account Processing  Significant risks with exposing transactional data  Implemented a WS-Security Gateway

OWASP AppSec Seattle Case Study 2 (Where did it all go wrong!)  Assumed WS-Security Protects 100%  Messages not sent over SSL (Sniffing/Replay)  XML Gateway Appliance misconfigured  Sensitive data was passed in clear text  API Toolkit was basic and had no security  Assumed XML Gateway was doing it’s job  Assumed end user’s knew what they were doing

OWASP AppSec Seattle What is WS-Security?  Provides a core standard framework and schema for XML messaging security  Implements the following capabilities for XML  Authentication  Confidentiality  Integrity

OWASP AppSec Seattle WS-Security Messages

OWASP AppSec Seattle Implementing WS-Security Securely  Ensure you are using Standard 1.1 (latest)  Implement an Authentication Token (either UsernameToken, BinaryToken, etc.)  Provide a Digital Hash of the Message (integrity)  Use Message encryption if passing sensitive data  Implement SSL technology to ensure messages cannot be captured and replayed  Use a WS-* Gateway to inspect and verify messages received prior to receiving them on the Web Service Endpoint

OWASP AppSec Seattle Web Service Appliance/Gateways  Market Space is Growing in size (Rapidly)  Vendor solutions provides assistance to the problem and are not a complete solution  Use all the features not just the simple things  WS-Security Authentication Validation  Schema Validation  Search for known common exploits in strings (i.e. SQL Injection, XSS Attacks, etc.)  Specify trusted hosts (IP Addresses or Agent Types) & Restrict

OWASP AppSec Seattle Other Standards XML (WS-*)  Oasis-Open Working groups releasing other standards for XML Web Services

OWASP AppSec Seattle Common Mistakes  Assumption that WS-Security solves everything  Assumption (No Interface means no attacks – service is hidden)  Belief in vendors without performing testing  Supply insecure API to remote users  Forget to disable WSDL publishing of service  Web Service has minimal or no application security controls (i.e. OWASP Top Ten)

OWASP AppSec Seattle OWASP Top Ten & Web Services  (1) Data Validation = Validate Everything  (2) Access Control = Implement Authentication (WS-Security)  (3) Authentication/Session Management = Replay attacks in XML  (4) Cross Site Scripting = (See – 1, Integration with applications)  (5) Buffer Overflow = Watch for this, validate and address in code  (6) Injection Flaws = Watch for this, validate and address in code  (7) Error Handling = Don’t return detailed error messages  (8) Insecure Storage = Watch for this, store appropriately  (9) Denial of Service = Detect & Alert, similar to web application  (10) Insecure Configuration Management = Similar to web application (Avoid WSDL Publishing etc unless necessary)

OWASP AppSec Seattle Summary  Implement WS-Security (C,I,A)  Implement OWASP Guidelines for Applications  Identify & Test Vendor Applications  Don’t rely 100% on XML security gateways to provide all the security  Disable WSDL Publishing if you don’t need it

OWASP AppSec Seattle Questions? Justin Derry Application Security Practice Leader B-sec Consulting Pty Ltd (Australia)