Preventing CSRF with the same-site cookie attribute

 

After Deep review on HttpCookie Source it's confirm that we cannot do this with the code, as there is no way to add extra attribute on Cookie and class is marked as sealed.

But still anyhow I manage solution by modifying web.config as below.

<rewrite>
  <outboundRules>
    <rule name="Add SameSite" preCondition="No SameSite">
      <match serverVariable="RESPONSE_Set_Cookie" pattern=".*" negate="false" />
      <action type="Rewrite" value="{R:0}; SameSite=strict" />
      <conditions>
      </conditions>
    </rule>
    <preConditions>
      <preCondition name="No SameSite">
        <add input="{RESPONSE_Set_Cookie}" pattern="." />
        <add input="{RESPONSE_Set_Cookie}" pattern="; SameSite=strict" negate="true" />
      </preCondition>
    </preConditions>
  </outboundRules>
</rewrite>