[SOLVED] CS Java SQL python cache jquery js javascript Web Security

Web Security
1

Today
Web architecture
Basics of web security
2

What is the Web?
A platform for deploying applications, portably and securely
3

Web security: two sides
Web browser: (client side)
Interacts with the user
Fetches and renders pages from the server
Worry about users own data, malware, keyloggers,
Web application code: (server side)
Runs at web site: banks, e-merchants, blogs
Written in PHP, ASP, JSP, Python, Ruby, Node.js,
Decides which page to serve to which users/requests (authorized users, dynamic content, etc)
Worry about all users data, targeted attacks,
4

A historical perspective
The web is an example of bolt-on security
Originally, the web was invented to allow
physicists to share their research papers
Only textual web pages + links to other pages; no security model to speak of
Then we added embedded images
Crucial decision: a page can embed images loaded
from another web server
Then, Javascript, dynamic HTML, AJAX, CSS, frames, audio, video,
Today, a web site is a distributed application
5

URLs
Global identifiers of network-retrievable documents
Example: http://ecen4133.org:80/tmp/test?foo=1337#top
host
Are URLs case-sensitive?
Fragment
Protocol
Path
Query
6

HTML
Hypertext markup language (HTML)
Describes the content and formatting of Web pages Rendered within browser window
HTML features
Static document description language
Supports linking to other pages and embedding images by reference
User input sent to server via forms
HTML extensions
Additional media content (e.g., PDF, video) supported through plugins
Embedding programs in supported languages (e.g., JavaScript, Java) provides dynamic content that interacts with the user, modifies the browser user interface, and can access the client computer environment
7

HTTP protocol
HTTP is
widely used Simple
Stateless
Unencrypted
8

HTTP Protocol
Method File HTTP version
Headers
GET /index.html HTTP/1.1 Host: www.example.com
HTTP Request HTTP Reply
Browser
HTTP version
Web Server
Status code
Reason phrase

HTTP/1.1 200 OK
Date: Tue, 14 Feb 2012
Server: Apache/1.3.3.7
Last-Modified: Mon, 13 Feb 2012 Content-Length: 438
Set-Cookie:
Content-Type: text/html; charset=UTF-8
Headers

Hello World!