A critical vulnerability (CVE-2022-1996) has been identified in the GitHub repository emicklei/go-restful prior to version v3.8., which affects the authorization process in the library. The vulnerability allows an attacker to bypass authorization controls by exploiting user-controlled keys. In this post, we will go through the details of the vulnerability, including its exploit, its impact, and the remediation steps required to fix this issue.

Vulnerability Details

The vulnerability lies in the way emicklei/go-restful handles authorization keys. Specifically, the library allows users to define custom keys that are then used for authorization purposes. However, this functionality does not properly restrict user-supplied keys, thereby allowing an attacker to bypass authorization checks by manipulating the key value.

Here's a code snippet that demonstrates how the vulnerability can be exploited

package main

import (
    "github.com/emicklei/go-restful/v3"
    "net/http"
)

func main() {
    ws := new(restful.WebService)
    ws.Route(ws.GET("/").To(handleRequest).Filter(authenticate))

    restful.Add(ws)
    http.ListenAndServe(":808", nil)
}

func authenticate(request *restful.Request, response *restful.Response, chain *restful.FilterChain) {
    authKey := request.Request.Header.Get("X-Auth-Key")
    if authKey == "secret-key" {
        chain.ProcessFilter(request, response)
    } else {
        response.WriteErrorString(http.StatusForbidden, "Forbidden")
    }
}

func handleRequest(request *restful.Request, response *restful.Response) {
    response.Write([]byte("Hello, authorized user!"))
}

In this example, the authenticate function is intended to allow access to the / endpoint only if the X-Auth-Key header matches the value "secret-key". However, an attacker can exploit this vulnerability by altering the value of the X-Auth-Key header and bypassing this check.

Impact

With this vulnerability, an attacker could gain unauthorized access to protected resources, potentially leading to unauthorized data access, manipulation, and other security breaches.

Remediation

To fix this vulnerability, users should update their emicklei/go-restful library to version v3.8. or later. The updated version includes a fix for this issue, ensuring that user-supplied keys are properly restricted and cannot be manipulated by an attacker.

Updating the library can be done by running the following command in your project directory

go get -u github.com/emicklei/go-restful/v3@v3.8.

Ensure that your project's go.mod file reflects the new version of the library.

Original Reference

For more information on this vulnerability, you can refer to the official GitHub security advisory GHSA-7v2w-8p67-mrw7, which provides additional details and context around the issue.

Conclusion

The CVE-2022-1996 vulnerability in emicklei/go-restful (prior to v3.8.) is a serious issue that enables attackers to bypass authorization controls by exploiting user-controlled keys. To protect your applications from exploitation, it is crucial to update the library to version v3.8. or later and ensure proper usage of authorization checks.

Timeline

Published on: 06/08/2022 13:15:00 UTC
Last modified on: 08/17/2022 04:15:00 UTC