Lack of data validation - Header x-amzn-RequestId - Go

Need

Implementation of strict data validation for the x-amzn-RequestId Header

Context

1. Usage of Go 1.16 for building efficient and scalable applications
2. Usage of Gin for building web applications in Go

Description

Insecure Code Example

package main

import (
    "github.com/gin-gonic/gin"
)

func main() {
    r := gin.Default()

    r.POST("/data", func(c *gin.Context) {
        xAmznRequestId := c.GetHeader("x-amzn-RequestId")
        // process the request with the xAmznRequestId
    })

    r.Run()
}

In the code above, the server is using the Gin framework to handle HTTP requests. In the POST route handler for "/data", it is attempting to retrieve the value of the "x-amzn-RequestId" header from the request context. The vulnerability lies in the fact that there is no validation performed on the value of the "x-amzn-RequestId" header. This means that a malicious user could potentially pass in a dangerous character string via this header, which could lead to various types of attacks such as SQL Injection, Cross-Site Scripting (XSS), or Remote Code Execution (RCE), depending on how the server uses this header value. In addition, the server does not control server-side permission to modify certain fields, including the "x-amzn-RequestId" header. This means that a malicious user could potentially modify this header value in a way that could compromise the server's security or functionality. To mitigate this vulnerability, the server should implement input validation for the "x-amzn-RequestId" header value, and control server-side permission to modify this header.

Steps

1. Implement server-side validation for the x-amzn-RequestId header.
2. Define a whitelist of allowed characters for the x-amzn-RequestId header.
3. Reject or sanitize any input that contains potentially dangerous characters.
4. Use regular expressions or string manipulation functions to validate the input.
5. Consider using a middleware to handle the validation logic for all routes.
6. Return an appropriate error response if the input is invalid.

Secure Code Example

package main

import (
    "github.com/gin-gonic/gin"
    "net/http"
    "regexp"
)

func main() {
    r := gin.Default()

    r.Use(validateRequestId())

    r.POST("/data", func(c *gin.Context) {
        xAmznRequestId := c.GetHeader("x-amzn-RequestId")
        // process the request with the xAmznRequestId
    })

    r.Run()
}

func validateRequestId() gin.HandlerFunc {
    return func(c *gin.Context) {
        xAmznRequestId := c.GetHeader("x-amzn-RequestId")
        match, _ := regexp.MatchString("^[a-zA-Z0-9-]*$", xAmznRequestId)
        if !match {
            c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid x-amzn-RequestId header"})
            c.Abort()
            return
        }
        c.Next()
    }
}

The updated code includes a middleware function `validateRequestId()` that validates the `x-amzn-RequestId` header for every request. This function is added to the Gin engine using the `Use()` function, which applies it to all routes. The `validateRequestId()` function retrieves the `x-amzn-RequestId` header from the request context and checks it against a regular expression. The regular expression `^[a-zA-Z0-9-]*$` only allows alphanumeric characters and hyphens. This is a common pattern for request IDs, but you should adjust it according to your specific requirements. If the `x-amzn-RequestId` header does not match the regular expression, the function responds with a 400 Bad Request status and an error message. It also calls `c.Abort()` to prevent further processing of the request. If the `x-amzn-RequestId` header is valid, the function calls `c.Next()` to allow the next handler in the chain to process the request. This approach ensures that all requests have a valid `x-amzn-RequestId` header before they are processed by your application. It helps to prevent injection attacks and other security vulnerabilities related to unvalidated input.

References

Last updated

2023/09/18