Project: WASC Threat Classification

Threat Type: Attack

Reference ID: WASC-9


Cross-Site Request Forgery

A cross-site request forgery is an attack that involves forcing a victim to send an HTTP request to a target destination without their knowledge or intent in order to perform an action as the victim. The underlying cause is application functionality using predictable URL/form actions in a repeatable way. The nature of the attack is that CSRF exploits the trust that a web site has for a user. By contrast, cross-site scripting (XSS) [9] exploits the trust that a user has for a web site. Like XSS, CSRF attacks are not necessarily cross-site, but they can be. Cross-site request forgery is also known as CSRF, XSRF, one-click attack, session riding, confused deputy, and sea surf.


CSRF attacks are effective in a number of situations, including:

  • The victim has an active session on the target site.
  • The victim is authenticated via HTTP auth on the target site.
  • The victim is on the same local network as the target site.


CSRF has primarily been used to perform an action against a target site using the victim’s privileges, but recent techniques have been discovered [5] to disclose information by gaining access to the response. The risk of information disclosure is dramatically increased when the target site is vulnerable to XSS, because XSS can be used as a platform for CSRF, allowing the attack to operate within the bounds of the same-origin policy.