The document presents a presentation by Jeremiah Grossman on web application security, discussing its importance and common mistakes such as trusting client-side data and improper input handling. It details various attack methodologies including cross-site scripting, parameter tampering, and session management issues. Additionally, it offers recommendations for securing web applications by filtering and escaping input data and not relying on client-side data validation.

1. Black Hat New Orleans Windows Security 2002 “ Web Application Security and Arsenal” Presenter: Jeremiah Grossman Copyright 2002 WhiteHat Security All Rights Reserved

2. Topics Web Application Security Landscape Why is Web Application Security Important Common Web Application Security Mistakes Web Application Attack Methodologies

3. Web Application Security Landscape Entertainment Message Boards WebMail Guest Books Voting Polls E-Commerce Shopping Auctions Banking Stock Trading Just Plain Crazy Printers PDA’s Cell Phones System Configuration .NET/Passport

4. Web Application The Simple Definition A web application or web service is a software application that is accessible using a web browser or HTTP(s) user agent.

5. Web Application The “EASIER” Definition If it runs on port 80 or port 443, then is probably a web application.

9. Why is Web Application Security Important? Easiest way to compromise hosts, networks and users. Widely deployed. No Logs! (POST Request payload) Incredibly hard to defend against or detect. Most don’t think of locking down web applications. Intrusion detection is a joke. Firewall? What firewall? I don’t see no firewall… Encrypted transport layer does nothing. How much easier can it get!? Unicode.

10. Common Web Application Security Mistakes Trusting Client-Side Data Unescaped Special Characters HTML Output Character Filtering SUID ActiveX/JavaScript Authentication Lack of User Authentication before performing critical task.

11. Trusting Client-Side Data DO NOT TRUST CLIENT-SIDE DATA!!! Trusting client-side data is #1 cause of vulnerabilities. Identify all input parameters that trust client-side data.

12. Unescaped Special Characters The Level of Trust : Searches/Queries/Templates Path: http://foo.com/cgi?val=string&file=/html/name.db Or better yet… http://www.foo.com/cgi?string=root&file=../../../../../etc/passwd

13. Unescaped Special Characters ! @ $ % ^ & * ( ) -_ + ` ~ \ | [ ] { } ; : ' &quot; ? / , . > < Check for: Unescaped special characters within input strings

14. HTML Character Filtering Proper handling of special characters > => &gt; < => &lt; &quot; => &quot; & => &amp; Null characters should all be removed. %00

15. More mistakes… SUID (Does a web application really need root?) Authentication mechanisms using technologies such as JavaScript or ActiveX. Lack of re-authenticating the user before issuing new passwords or performing critical tasks. Hosting of uncontrolled data on a protected domain.

16. WhiteHat Arsenal GUI Web-Based Interface Session Based Discovery Utilities Active Assessment Encoding/Decoding Reporting

17. Web Application Penetration Methodologies Information Gathering & Discovery Input/Output Client-Side Data Manipulation

18. Information Gathering & Discovery Spidering /Site Map Identifiable Characteristics Error and Response Codes File / Application Enumeration

19. Spidering

20. Spidering/Site Crawling Site Map Service Map Documentation Hidden Services CGI's and Forms Email addresses

21. Identifiable Characteristics Comment Lines URL Extensions Meta Tags Cookies Client-Side scripting languages Enormous wealth of information about process flows, debug command, system types and configurations.

22. Error and Response Codes HTTP Response Headers Server: IBM/Apache 1.3.19 Cookie Characteristics Error Messages Exception Messages (Java / SQL) 404 Error Pages Failed Login Locked Account Database or file non-existent

23. File/Application Enumeration Commonly referred to as “forced browsing” or “CGI Scanning”.

24. File/Application Enumeration Sample Files Template Directories Temp or Backup files Hidden Files Vulnerable CGIs

25. Common Directories

26. Common Log Files

27. Common Backup Files

28. Input/Output Client-Side Data Manipulation URL Manipulation CGI Parameter Tampering HTTP Client-Header Injection Filter/Intrusion Detection Evasion Protocol/Method Manipulation Overflows

29. Input Manipulation Parameter Tampering &quot;Twiddling Bits.&quot; Cross-Site Scripting Filter-Bypass Manipulation OS Commands Meta Characters Path/Directory Traversal Hidden Form Field Manipulation HTTP Headers

30. Cross-Site Scripting Bad name given to a dangerous security issue Attack targets the user of the system rather than the system itself. Outside client-side languages executing within the users web environment with the same level of privilege as the hosted site.

31. Client-Side Scripting Languages DHTML (HTML, XHTML, HTML x.0) Opens all the doors. JavaScript (1.x) Browser/DOM Manipulation Java (Applets) Malicious Applets VBScript Browser/DOM Manipulation Flash Dangerous Third-Party Interactivity ActiveX Let me count the ways… XML/XSL Another Door Opener CSS Browser/DOM Manipulation

32. The Scenarios Trick a user to re-login to a spoofed page Compromise authentication credentials Load dangerous of malicious ActiveX Re-Direct a user or ALL users Crash the machine or the browser

33. CSS Danger “The Remote Launch Pad.” Successfully CSS a user via a protected domain. Utilizing a Client-Side utility (JavaScript, ActiveX, VBScript, etc.), exploit a browser hole to download a trojan/virus. User is unknowingly infected/compromised within a single HTTP page load. ActiveX Netcat Anyone?

34. 2 Types of CSS Click on a link to activate <A HREF=“http://www.evil_javascript_link”> Click Here </A> Auto-Execute by viewing HTML <SCRIPT>run evil JavaScript</SCRIPT>

35. Dangerous HTML “HTML Bad” <APPLET> Malicious Java Applications <BODY> Altering HTML Page Characteristics <EMBED> Embedding Third-Party Applications (Flash, etc.) <FRAME> Directly calling in other uncontrolled HTML <FRAMESET> Directly calling in other uncontrolled HTML <HTML> Altering HTML Page Characteristics <IFRAME> Directly calling in other uncontrolled HTML <IMG> SCRing Protocol attacks and other abuses <LAYER> Directly calling in other uncontrolled HTML <ILAYER> Directly calling in other uncontrolled HTML <META> META Refreshes. (Client-Redirects) <OBJECT> ActiveX (Nuff Said) <SCRIPT> JavaScript/VBScript Loading <STYLE> Style Sheet and Scripting Alterations

36. Dangerous Attributes “Attributes Bad” ATTRIBUTE DANGER LIST (Any HTML Tag that has these attributes) STYLE SRC HREF TYPE

37. Power of the Dots and Slashes piping input to the command line. Path Directory Traversal http://foo.com/app.cgi?directory=/path/to/data DotDot Slash: http://foo.com/app.cgi?dir=path/to/data../../../../etc/passwd Dot Slash: http://foo.com/app.cgi?dir=path/to/data../../../../etc/././passwd Double DotDot Slash: http://foo.com/app.cgi?dir=path/to/data....//….//….//etc/passwd

38. More Filter Bypassing Method Alteration (HEAD, PUT, POST, GET, ect.) URL Encode http://www.foo.com/cgi?value=%46%72%68%86 Null Characters http://www.foo.com/cgi?value=file%00.html More… Alternate Case, Unicode, String Length, Multi-Slash, etc.

39. Authentication & Session Management Brute/Reverse Force Session Hi-Jacking Session Replay Session Forgoing Page Sequencing

40. Reporting XML/HTML Based Manual Hack Attack Log w/ Descriptor Common Directory Force Browsing Common Log File Force Browsing Backup File Force Browsing Spider Log

41. Spider XML Log

42. Attempts XML Log

43. A few quick things to help secure a web application. Do Not Trust Client-Side Data Escape and filter all input/output data Set-up parameter and request method allow lists. Don’t use what your not expecting to receive.

44. Thank You! Questions? Jeremiah Grossman [email_address] WhiteHat Security All presentation updates will be available on www.whitehatsec.com and community.whitehatsec.com