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CSRF-ATTACK

this section is talking about csrf attack and its prevention

If you have not been familiar with HTML / HTTP, you can pass this section temporily

Table of Contents

CSRF

CSRF ( Cross-site request forgery ) is a type of malicious exploit of a website whereby unauthorized commands are transmitted from a user that the website trusts

CSRF-Examples

  1. If a bank transfer money by a url http://www.examplebank.com/withdraw?amount=A&for=B
  • A is the amount to transfer
  • B is the target account name

  1. An attacker send a link to victims via email http://www.examplebank.com/withdraw?amount=1000&for=AttackerAccount

  2. Any logged in victim click the link would send $1000 to AttackerAccount

CSRF-XSS

  • XSS exploits the trust a user has for a particular site
  • CSRF exploits the trust that a site has in a user's browser

CSRF-Prevention

  • Synchronizer Token Pattern
    1. Server generate a unique secret token and bind it to user session
    2. Server render the form with that token
    <input type="hidden" name="csrfmiddlewaretoken" value="KbyUmhTLMpYj7CD2di7JKP1P3qmLlkPt" />
    1. When client request comes, check the request token with the session token
    • same as session token : valid request
    • different from session token : invalid request
    1. destroy the token in session

References