Implementation of secure and appropriate Cache Control headers
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
}
The code above is a simple HTTP server written in Go using the Gin framework. The server has a single route ("/") that responds with "Hello, World!".
The vulnerability lies in the lack of HTTP security headers, specifically the Cache-Control header. The Cache-Control header defines how, and for how long the individual response can be cached by the browser and other intermediate caches.
Without the Cache-Control header, or if it's set with insecure values, sensitive information might be stored in caches and could be accessed by unauthorized users. This can lead to information disclosure and other security issues.
In the provided code, there is no Cache-Control header set in the server responses, which makes the application vulnerable to the mentioned risks.
package main
import (
"github.com/gin-gonic/gin"
)
func main() {
r := gin.Default()
r.Use(func(c *gin.Context) {
c.Header("Cache-Control", "no-store, no-cache, must-revalidate")
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 updated code includes a middleware function that sets the
Cache-Control header to a secure value (
no-store, no-cache, must-revalidate) for all HTTP responses. This function is added using the
Use method of the gin router (
r), which applies the middleware to all routes and endpoints in the application.
The
Cache-Control header is used to prevent sensitive information from being stored in the cache of the client's web browser. By setting this header to
no-store, no-cache, must-revalidate, the application instructs the browser not to store the response in its cache, not to use a cached response to satisfy a subsequent request without successful validation on the server, and to revalidate the cache entry after every request.
This change helps to mitigate the risk of sensitive information being exposed through the browser's cache, which could potentially be accessed by an attacker.
After updating the code, it's important to test the application to verify that the
Cache-Control header is being set correctly for all relevant routes and endpoints. Once this has been confirmed, the updated code can be deployed to production.