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Java Secure Coding Practices

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Slides Used by Rajesh Nair - In OWASP Kerala Chapter Meet April 2015

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Java Secure Coding Practices

  1. 1. The OWASP Foundation http://www.owasp.org Escape ’Attacks!’ India, Kerala 2015 Rajesh P Board Member, OWASP Kerala Copyright © The OWASP Foundation Permission is granted to copy, distribute and/or modify the document under the terms of the OWASP License All trademarks, service marks, trade names, product names and logos appearing on the slides are the property of their respective owners Secure Coding Practice Series Parse what you code
  2. 2. The OWASP Foundation http://www.owasp.org 2
  3. 3. The OWASP Foundation http://www.owasp.org • Developer approaches application based on what it is intended to do • Attacker’s approach is based on what application can be made to do • Any action not specifically denied is considered allowed 3 Fundamental difference
  4. 4. The OWASP Foundation http://www.owasp.org • Minimize Attack Surface Area • Secure Defaults • Principle of Least Privilege • Principle of Defense in Depth • Fail Securely • External Systems are Insecure • Separation of Duties • Do not trust Security through Obscurity • Simplicity • Fix Security Issues Correctly 4 Security Principles
  5. 5. The OWASP Foundation http://www.owasp.org • Price related hidden fields, CSS visibility – perform server side validation • Cross Site Request Forgery (CSRF) • Sensitive Information Disclosure via Client- Side Storage and Comments • Hardcoded domain in HTML • HTML5: Form validation turned off • Password Submission using GET method 5 HTML
  6. 6. The OWASP Foundation http://www.owasp.org • Selects, radio buttons, and checkboxes Wrong Approach <input type="radio" name="acctNo" value="455712341234">Gold Card <input type="radio" name="acctNo" value="455712341235">Platinum Card String acctNo = getParameter('acctNo'); String sql = "SELECT acctBal FROM accounts WHERE acctNo = '?'"; 6 HTML
  7. 7. The OWASP Foundation http://www.owasp.org Right Approach <input type="radio" name="acctIndex" value="1" />Gold Credit Card <input type="radio" name="acctIndex" value="2" />Platinum Credit Card String acctNo = acct.getCardNumber(getParameter('acctIndex')) String sql = "SELECT acctBal FROM accounts WHERE acct_id = '?' AND acctNo ='?'"; 7 HTML
  8. 8. The OWASP Foundation http://www.owasp.org • Display of passwords in form, Autocomplete • Don’t populate password in form <input name="password" type="password" value="<%=pass%>" /> 8 HTML
  9. 9. The OWASP Foundation http://www.owasp.org • Ajax Hijacking • Cross Site Scripting: DOM, Poor validation • Dynamic code evaluation: Code, Script Injection, Unsafe XMLHTTPRequest – eval • Open Redirect • Path Manipulation – dot dot slash attack • Obfuscate Client Side JavaScript. Remember the jQuery.min, jQuery.dev versions 9 JavaScript
  10. 10. The OWASP Foundation http://www.owasp.org • jQuery Unsafe usage var txtAlertMsg = "Hello World: "; var txtUserInput = "test<script>alert(1)</script>"; $("#message").html( txtAlertMsg +"" + txtUserInput + ""); Safe usage (use text, not html) $("#userInput").text( "test<script>alert(1)</script>"); <-- treat user input as text 10 JavaScript
  11. 11. The OWASP Foundation http://www.owasp.org • Use of =, != for null comparison • Ignoring exception – try & catch • Persistent Cross Site Scripting • Use parameterized statements, validate input before string concatenation in dynamic SQL’s in stored procedures • Avoid xp_cmdshell • Never store passwords in plaintext 11 SQL
  12. 12. The OWASP Foundation http://www.owasp.org • Use stored procedures to abstract data access and allow for the removal of permissions to the base tables in the database 12 SQL
  13. 13. The OWASP Foundation http://www.owasp.org • The Java libraries (java.lang, java.util etc, often referred to as the Java API) are themselves written in Java, although methods marked as native. The Sun JVM is written in C, JVM running on your machine is a platform-dependent executable and hence could have been originally written in any language. The Oracle JVM (HotSpot) is written in the C++ programming language. Java Compiler provided By Oracle is written in JAVA itself. Many Java vulnerabilities are really C vulnerabilities that occur in an implementation of Java. 13 About Java
  14. 14. The OWASP Foundation http://www.owasp.org • Secure data types – char[], GuardedString • Zip Bombs private static final int LINE_LIMIT = 1000000; int totalLinesRead = 0; while ((s = reader.readLine()) != null) { doSomethingWithLine(s); totalLinesRead++; if (totalLinesRead > LINE_LIMIT) { throw new Exception("File being read is too big."); } } 14 Java
  15. 15. The OWASP Foundation http://www.owasp.org • Do not ignore values returned by methods. private void deleteFile() { File tempFile = new File(tempFileName); if (tempFile.exists()) { if (!tempFile.delete()) { // handle failure to delete the file } } } 15 Java
  16. 16. The OWASP Foundation http://www.owasp.org • Release resources in all cases. The try-with- resource syntax introduced in Java SE 7 automatically handles the release of many resource types. try (final InputStream in = Files.newInputStream(path)) { handler.handle(new BufferedInputStream(in)); } 16 Java - DOS
  17. 17. The OWASP Foundation http://www.owasp.org • Billion laughs attack - XML entity expansion causes an XML document to grow dramatically during parsing. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); dbf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSI NG, true); DocumentBuilder parser = dbf.newDocumentBuilder(); parser.parse(xmlfile); 17 Java
  18. 18. The OWASP Foundation http://www.owasp.org • Add security wrapper around native method calls – use JNI defensively • Make public static fields final • java.lang.SecurityManager – policy • In Struts deny direct jsp access explicitly • Use SecureRandom for PRNG, 128 bit length SecureRandom random = new SecureRandom(); byte bytes[] = new byte[20]; random.nextBytes(bytes); 18 Java
  19. 19. The OWASP Foundation http://www.owasp.org • JSP Source code disclosure • Non-Final classes let an attacker extend a class in a malicious manner • Packages are by default open, not sealed, which means a rogue class can be added to your package • Check uploaded file header than just extension alone https://www.owasp.org/images/0/08/OWASP_S CP_Quick_Reference_Guide_v2.pdf 19 Java
  20. 20. The OWASP Foundation http://www.owasp.org • Override the clone method to make classes unclonable unless required. Cloning allows an attacker to instantiate a class without running any of the class constructors. 20 Java Cloning
  21. 21. The OWASP Foundation http://www.owasp.org • Define the following method in each of your classes: public final Object clone() throws java.lang.CloneNotSupportedException { throw new java.lang.CloneNotSupportedException(); } 21 Java Cloning
  22. 22. The OWASP Foundation http://www.owasp.org • If a clone is required, one can make one’s clone method immune to overriding by using the final keyword: public final Object clone() throws java.lang.CloneNotSupportedException { return super.clone(); } 22 Java Cloning
  23. 23. The OWASP Foundation http://www.owasp.org • Unfavour serialization of objects containing sensitive information – transient fields private final void writeObject(ObjectOutputStream out) throws java.io.IOException { throw new java.io.IOException("Object cannot be serialized"); } 23 Java Serialization
  24. 24. The OWASP Foundation http://www.owasp.org • Prevent deserialization of objects containing sensitive information private final void readObject(ObjectInputStream in) throws java.io.IOException { throw new java.io.IOException("Class cannot be deserialized"); } 24 Java Deserialization
  25. 25. The OWASP Foundation http://www.owasp.org • deny access by default isAdmin = false; try { codeWhichMayFail(); isAdmin = isUserInRole(“Administrator”); } catch (Exception ex) { log.write(ex.toString()); } 25 Java
  26. 26. The OWASP Foundation http://www.owasp.org 26 Return after sendRedirect
  27. 27. The OWASP Foundation http://www.owasp.org • Response splitting allows an attacker to take control of the response body by adding extra CRLFs into headers String author = request.getParameter(AUTHOR_PARAM); ... Cookie cookie = new Cookie("author", author); cookie.setMaxAge(cookieExpiration); response.addCookie(cookie); 27 Response Splitting
  28. 28. The OWASP Foundation http://www.owasp.org If an attacker submits a malicious string, such as “Rajesh PrnHTTP/1.1 200 OKrn...", then the HTTP response would be split into two responses of the following form: HTTP/1.1 200 OK ... Set-Cookie: author=Rajesh P HTTP/1.1 200 OK ... Clearly, the second response is completely controlled by the attacker and can be constructed with any header and body content desired. Response Splitting
  29. 29. The OWASP Foundation http://www.owasp.org Attacker Proxy Web Server 302 302 200 (Gotcha!) 1st attacker request (response splitter) 1st attacker request (response splitter) request /account?id=victim 200 (Gotcha!) 200 (Victim’s account data) Victim request /index.html request /index.html 200 (Victim’s account data) Response Splitting
  30. 30. The OWASP Foundation http://www.owasp.org • How to Identify new vulnerability disclosures in Java? – NVD, CVE • Always remove older versions of Java on devices while updating to the new secure version 30 Miscellaneous
  31. 31. The OWASP Foundation http://www.owasp.org The OWASP Enterprise Security API Custom Enterprise Web Application Enterprise Security API Authenticator User AccessController AccessReferenceMap Validator Encoder HTTPUtilities Encryptor EncryptedProperties Randomizer ExceptionHandling Logger IntrusionDetector SecurityConfiguration Existing Enterprise Security Services/Libraries 31
  32. 32. The OWASP Foundation http://www.owasp.org Validate: getValidDate() getValidCreditCard() getValidInput() getValidNumber() … Validating Untrusted Input / Output BackendController Business Functions User Data Layer Presentation Layer Validate: getValidDate() getValidCreditCard() getValidSafeHTML() getValidInput() getValidNumber() getValidFileName() getValidRedirect() safeReadLine() … Validation Engine Validation Engine
  33. 33. The OWASP Foundation http://www.owasp.org OWASP Top Ten Coverage 33 OWASP Top Ten A1. Cross Site Scripting (XSS) A2. Injection Flaws A3. Malicious File Execution A4. Insecure Direct Object Reference A5. Cross Site Request Forgery (CSRF) A6. Leakage and Improper Error Handling A7. Broken Authentication and Sessions A8. Insecure Cryptographic Storage A9. Insecure Communications A10. Failure to Restrict URL Access OWASP ESAPI Validator, Encoder Encoder HTTPUtilities (upload) AccessReferenceMap User (csrftoken) EnterpriseSecurityException, HTTPUtils Authenticator, User, HTTPUtils Encryptor HTTPUtilities (secure cookie, channel) AccessController
  34. 34. The OWASP Foundation http://www.owasp.org • Disgruntled staff • Unintentional program execution • Identify Training need, Certification • Urgent and Frequent patches • Selection of Third Party Libraries • “Drive by” attacks, such as side effects or direct consequences of a virus, worm or Trojan attack 34 Why Static Code Analysis
  35. 35. The OWASP Foundation http://www.owasp.org • Categories of Vulnerability Sources • URL, Parameter Tampering • Header Manipulation • Cookie Poisoning • Categories of Vulnerability Sinks • SQL, XPath, XML, LDAP Injection • Cross-site Scripting • HTTP Response Splitting • Command Injection • Path Traversal 35 LAPSE+ Static Code Analysis
  36. 36. The OWASP Foundation http://www.owasp.org 36 Free Static Analysis Tools
  37. 37. The OWASP Foundation http://www.owasp.org Thank you! Until next time, stay secure! rajesh.nair@owasp.or g https://www.facebook.com/OWASPKerala https://www.twitter.com/owasp_kerala

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