Windows Security 2002 BlackHat New Orleans WhiteHat Security “Web Application Security” and “Presenting” Jeremiah Grossman

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

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

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.

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

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.

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.

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.

Unescaped Special Characters The Level of Trust : Searches/Queries/Templates Path: Or better yet…

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

HTML Character Filtering Proper handling of special characters > =>> < "=>" & =>& Null characters should all be removed. %00

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.

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

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

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

Spidering

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

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.

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

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

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

Common Directories

Common Log Files

Common Backup Files

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

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

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.

Client-Side Scripting Languages DHTML (HTML, XHTML, HTML x.0) Opens all the doors. " JavaScript (1.x)Browser/DOM Manipulation " Java (Applets)Malicious Applets " VBScriptBrowser/DOM Manipulation " FlashDangerous Third-Party Interactivity " ActiveXLet me count the ways… " XML/XSLAnother Door Opener " CSSBrowser/DOM Manipulation

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

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?

2 Types of CSS  Click on a link to activate Click Here  Auto-Execute by viewing HTML run evil JavaScript

Dangerous HTML “HTML Bad” " Malicious Java Applications " Altering HTML Page Characteristics " Embedding Third-Party Applications (Flash, etc.) " Directly calling in other uncontrolled HTML " Altering HTML Page Characteristics " Directly calling in other uncontrolled HTML " SCRing Protocol attacks and other abuses " Directly calling in other uncontrolled HTML " META Refreshes. (Client-Redirects) " ActiveX (Nuff Said) " JavaScript/VBScript Loading " Style Sheet and Scripting Alterations

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

Power of the Dots and Slashes piping input to the command line. " Path Directory Traversal " " DotDot Slash: " " Dot Slash: " " Double DotDot Slash: "

More Filter Bypassing " Method Alteration(HEAD, PUT, POST, GET, ect.) " URL Encode " " Null Characters " " More… " Alternate Case, Unicode, String Length, Multi-Slash, etc.

More Filter Bypassing " Method Alteration(HEAD, PUT, POST, GET, ect.) " URL Encode " " Null Characters " " More… " Alternate Case, Unicode, String Length, Multi-Slash, etc.

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

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

Spider XML Log

Attempts XML Log

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.

Thank You! BlackHat and Attendees Questions? Jeremiah Grossman WhiteHat Security All presentation updates will be available on and community.whitehatsec.com