Copyright © The OWASP Foundation Permission is granted to copy, distribute and/or modify this document under the terms of the OWASP License. The OWASP Foundation OWASP Attacking Web Services Jason Alexander

OWASP 2 What are Web Services?  No single definition  SOA, SOAP, REST, XML, WSDL, UDDI “ A web service is a software component developed to support interoperability over a network using an interface described in WSDL. Other systems communicate with the web service using SOAP messages that are typically transported using the HTTP protocol with XML messaging.”

OWASP What are Web Services..cont  For our purposes, web services are communication protocols that:  Use XML as the base meta language  Provide computer to computer communication  Use standard protocols, often in line with W3C, OASIS and WS-I  Designed to be platform and transport independent 3

OWASP What are Web Services..cont  Why are they popular? -Quote “lets expose our mainframe API’s through SOAP and use plentiful Java developers on Win/Lin instead of rare CICS developers on expensive mainframes to extend system functionality”  With an argument like that, what PHB could say no? 4

OWASP What are Web Services..cont  Usually deployed over port 80/443 Web Services We poke holes in your firewall so you don’t have to OR FBP -Firewall bypass protocol 5

OWASP Threats  All the “usual suspects”  Injection Attacks  Scripting Attacks  Broken Authentication  Security Mis-configuration  OWASP Top 10 any one? And more……… 6

OWASP Attacking Web Services  Follows basic concept of Web Application attacks  Discovery  Enumeration & information Gathering  Identifying Attack Vectors  Exploitation  Whitebox assessment – code analysis 7

OWASP Discovery  Find Web Services entry points  This is in the WSDL  How to find the WSDL?  UDDI –Universal Description Discovery and Integration  UBR – Universal Business Registry  Google is your friend !  inurl:wsdl site:example.com 8

OWASP Discovery..cont 9

OWASP Discovery..cont 10

OWASP Discovery..cont  Google Sample inurl:wsdl site:nhs.uk  ?WSDL  smx?WSDL   Crawling technique  wget –l 50 –r  Find. –name *wsdl* 11

OWASP Enumeration & information Gathering  Standard Web application enumeration  telnet  HEAD / HTTP/1.0  HTTP/ OK  Server Microsoft-IIS/5.0  X-Powered-By:ASP.net 12

OWASP Enumeration & information Gathering..cont  WSDL – All an attacker needs to know to interface with the service  Auto-Generated by WS framework  Generally not created or consumed by humans  No access controls generally enforced on WSDL’s  Do you really need to provide a WSDL ????? 13

OWASP Enumeration & information Gathering..cont  WSDL Example: Ebay Price Watching 14 <definitions name="eBayWatcherService" targetNamespace= " xmlns:tns=" e.wsdl" xmlns:xsd=" xmlns:soap=" xmlns=" <input message="tns:getCurrentPriceRequest" name="getCurrentPrice"/> <output message="tns:getCurrentPriceResponse" name="getCurrentPriceResponse"/> <soap:binding style="rpc" transport=" <soap:body use="encoded" namespace="urn:xmethods-EbayWatcher" encodingStyle=" /> <soap:body use="encoded" namespace="urn:xmethods-EbayWatcher" encodingStyle=" />

OWASP Enumeration & information Gathering..cont  Using Tools to profile web services  wsKnight  Wsdigger  SoapUI etc DEMO 15

OWASP Attack Vectors  Most of the web application attack vectors can be applied to web services  Injection & Scripting attacks apply  Specific SOAP orientated attacks  XML Poisoning  SOAP message brute forcing  SOAP parameter manipulation  XML parser attacks  Could take a whole lot of time to discuss all attacks! 16

OWASP Attack Vectors..cont  Spot the attack! <SOAP-ENV:Envelope SOAP-ENV:encodingStyle=" xmlns:SOAP-ENC=" xmlns:xsi=" xmlns:SOAP-ENV=" xmlns:xsd=" ' default 17

OWASP Attack Vectors..cont DEMO 18

OWASP Counter Measures  Do you need a WSDL?  Has it been sanitised?  Secure coding. Utilise OWASP resources  OWASP Coding guide – Input validation  OWASP TOP 10  OWASP Testing Guide  OWASP WS project – needs volunteers  es_Security_Project es_Security_Project 19

OWASP Counter Measures..cont  Protect messages in transit  TLS is the BEST option and fits most models  XML signing and encryption have their uses but are difficult to implement  WS-Security  Web Application Firewalls (WAF)  Do they work in a SOAP/XML environment?  New breed of technology – XML gateways!  Regular firewalls do not work! 20

OWASP Resources  DISCO:  UDDI OASIS Standard:  Understanding UDDI:  WebServices Testing: Tools  Net Square wsPawn  OWASP WebScarab: Web Services plugin OWASP WebScarab  Mac OSX Soap Client:  Foundstone WsDigger:  SoapBox  SoapUI:  SOAPClient4XG:  CURL: On-line tools  Web Services Directory:  Seekda:  UDDI Browser:  Xmethods:  WSIndex: 21

OWASP References   Hacking web services by Sheeraj Shah  How to Break Web Software by Mike Andrews and James Whittaker  Attacking Web Services by Alex Stamos 22