Cross-Site Request Forgery (CSRF) abuses the normal ability of browsers to make cross-origin requests by crafting a resource on one origin that causes a victims browser to make a request to another origin. CSRF takes advantage of web applications that fail to enforce strong authorization of actions during a user’s session. SOS is proposed an additional policy type of the Content Security Policy. The name is intended to evoke the SOS of Morse code, which is both easy to transmit and easy to understand.”]
Source: https://deadliestwebattacks.com/2013/08/08/and-they-have-a-plan/