JSF Input Validation
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SOURCE Seattle 2011 - Krishna Raja
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JSF Input Validation
- 1. JSF Security © 2011 Security Compass inc. 1
- 2. JSF Input Validation abcd <script> 24c;-- Validated Input © 2011 Security Compass inc. 2
- 3. MyFaces: validateRegExpr Tag <%@ taglib uri="http://myfaces.apache.org/tomahawk" prefix="t" %> Using Apache Tomahawk tag library <h:outputLabel for="zip1" value="Zip"/> <t:inputText value="#{order.zipCode}" id="zip1"> <t:validateRegExpr pattern="d{5}" message="ZIP Code must be 5 digits"/> </t:inputText> © 2011 Security Compass inc. 3
- 4. Facelets Implementation <html ... xmlns:ui="http://java.sun.com/jsf/facelets" xmlns:t="http://myfaces.apache.org/tomahawk"> <h:inputText type="text" id="val“ value="#{SimpleBean.val}" required="true"> <t:validateRegExpr pattern="[a-zA-Z]{1,100}" /> </h:inputText> © 2011 Security Compass inc. 4
- 6. Mojarra Validators xmlns:mj=http://mojarra.dev.java.net/mojarra_ext <h:inputText type="text" id="val“ value="#{SimpleBean.val}" required="true"> <mj:regexValidator pattern="[a-zA-Z]{1,50}"/> </h:inputText> There also exists: <mj:creditCardValidator/> © 2011 Security Compass inc. 6
- 7. JSF 2.0 Validators • Part of JSF 2.0 core tag library • Can leverage: – <f:validateLength …/> – <f:validateLongRange …/> – <f:validateDoubleRange …/> – <f:validateRegex pattern=“…”/> © 2011 Security Compass inc. 7
- 8. Demo: JSF 2.0 Validators
- 9. Other JSF Validation Techniques • Validation in Action Controller – Validation tied closely to biz logic – Dependence between different fields • Custom validation methods – More complex validation (i.e. built-in JSF validator doesn’t suit your need) © 2011 Security Compass inc. 9
- 10. Output Encoding in JSF <script>alert('xss') < > (') © 2011 Security Compass inc. 10
- 11. <h:outputText> & <h:outputFormat> <h:outputText value="#{param.name}"/> escape attribute is set to “true” by default <h:outputFormat value=“#{param.name}”/> © 2011 Security Compass inc. 11
- 12. Output encoding with Facelets <ui:define name="body"> This will safely encode as an HTML element in a Facelet: <h:outputText value="#{SimpleBean.val}"> </h:outputText> </ui:define> EL expression is automatically encoded © 2011 Security Compass inc. 12
- 13. But there’s a problem … • <h:outputText> and <h:outputFormat> cannot be used safely within: – HTML attribute – JavaScript or CSS • Similar problem with: Facelets ${bean.name} © 2011 Security Compass inc. 13
- 14. Problems with RichFaces • Some tags can lead to XSS • Never use user-supplied data with: – <a4j:loadScript> – <a4j:loadStyle> – <rich:componentControl> • Known vulnerabilities exist with: <rich:editor>, <rich:effect>, <rich:gmap>, <rich:virtualEarth> © 2011 Security Compass inc. 14
- 15. Solution: OWASP ESAPI EL <p> <input type="text“ value="${esapi:encodeForHTMLAttribute(dangerous)}"/> </p> <p> <script language="javascript"> var str=${esapi:encodeForJavaScript(dangerous)}; </script> </p> © 2011 Security Compass inc. 15
- 18. ESAPI AccessController • Interface that provides access control for – URLs – Business functions – Data services & files • Contains: – assertAuthorizedForURL(String URL) © 2011 Security Compass inc. 18
- 20. Defending Against CSRF Anti-CSRF tokens
- 21. What about JSF “view state”? • javax.faces.STATE_SAVING_METHOD – Can save and restore state of the view between requests to server STATE_SAVING_METHOD + JSESSIONID = Anti-CSRF Token ??? © 2011 Security Compass inc. 21
- 22. Problem: Padding Oracle Attack • Recently discovered exploit against CBC- mode encryption with PKCS#5 padding • Incorrect padding can result in java.crypto.BadPaddingException • Can use to decrypt STATE_SAVING_METHOD © 2011 Security Compass inc. 22
- 23. Solution: OWASP CSRF Guard • Version 3 recently released! • Library that injects per-session or per- request tokens into HTML • Can use 2 strategies to inject token: – JavaScript DOM Manipulation – JSP Tag Library © 2011 Security Compass inc. 23