Enforcement of secure and properly configured HTTP headers - Referrer-Policy
package main
import (
"github.com/gin-gonic/gin"
)
func main() {
r := gin.Default()
r.GET("/", func(c *gin.Context) {
c.String(200, "Hello, World!")
})
r.Run() // listen and serve on 0.0.0.0:8080
}
In the above code, we are setting up a simple server using the Gin framework in Go. The server responds to GET requests at the root ("/") endpoint with "Hello, World!".
However, the code is vulnerable because it does not set the
Referrer-Policy HTTP header. This header controls how much referrer information (sent via the
Referer header) should be included with requests.
Not setting the
Referrer-Policy or setting it to an insecure value can expose sensitive information in the URL, such as session IDs or other user-specific data, to other sites. This can lead to potential privacy leaks or other security issues.
In this case, the absence of the
Referrer-Policy means that browsers will use their default behavior, which might be to send the full URL in the
Referer header, potentially exposing sensitive data.
package main
import (
"github.com/gin-gonic/gin"
)
func main() {
r := gin.Default()
r.Use(func(c *gin.Context) {
c.Header("Referrer-Policy", "strict-origin-when-cross-origin")
c.Next()
})
r.GET("/", func(c *gin.Context) {
c.String(200, "Hello, World!")
})
r.Run() // listen and serve on 0.0.0.0:8080
}
The above code fixes the vulnerability by adding a middleware function that sets the
Referrer-Policy HTTP header to
strict-origin-when-cross-origin for all responses.
The middleware function is added using the
Use function of the gin router
r. This function takes a handler function as an argument, which is called for every HTTP request. The handler function sets the
Referrer-Policy header using the
Header method of the gin context
c. The
Next method is then called to pass control to the next middleware function in the chain.
The
strict-origin-when-cross-origin value for the
Referrer-Policy header means that the full URL will be sent as referrer to same-origin destinations, but only the origin will be sent as referrer to cross-origin destinations in a secure (HTTPS) context, and no referrer will be sent in an insecure (HTTP) context. This is a secure configuration that helps to protect sensitive information.
After adding the middleware function, the server is started with the
Run method as before. The server will now send the
Referrer-Policy header with all responses, not just the root route ('/').
You should test the application to ensure that the
Referrer-Policy header is being set correctly. You can do this by sending a request to the server and checking the headers in the response.