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Database

Lack of data validation - Header x-amzn-RequestId

Need

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

Context

• Usage of Go 1.16 for building efficient and scalable applications

• Usage of Gin for building web applications in Go

Description

1. Non compliant code

package main

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

func main() {
...

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.

2. Steps

• Implement server-side validation for the x-amzn-RequestId header.

• Define a whitelist of allowed characters for the x-amzn-RequestId header.

• Reject or sanitize any input that contains potentially dangerous characters.

• Use regular expressions or string manipulation functions to validate the input.

• Consider using a middleware to handle the validation logic for all routes.

• Return an appropriate error response if the input is invalid.

3. Secure code example

package main

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

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.

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