server-side-prototype-pollution.bcheck

metadata:
    language: v1-beta
    name: "Server-side prototype pollution (status)"
    description: "Server-side prototype pollution using the status technique"
    author: "Gareth Heyes"
    tags: "Server-Side Prototype Pollution"

define:
    payload = `,"__proto__":\{"status\":510\}\}`
    nullify = `,"__proto__":\{"status\":0\}\}`
    issueDetail = "Server-Side Prototype Pollution was found on this web site."
    issueRemediation = "Ensure that property keys, such as __proto__, constructor, and prototype are correctly filtered when merging objects.
                        When creating objects, we recommend using the Object.create(null) API to ensure that your object does not inherit
                        from the Object.prototype and, therefore, won't be vulnerable to prototype pollution."

given request then
    if {base.request.body} matches "^[{]" then
        send request called inject_sspp:
            method: "POST"
            body: {regex_replace({base.request.body}, "[}]$", {payload})}

        send request called check_sspp:
            method: "POST"
            body: "{,}"

        if {latest.response.body} matches "\"statusCode\":510" or
            {latest.response.status_code} is "510" then
            send request called clean_sspp:
                method: "POST"
                body: {regex_replace({base.request.body}, "[}]$", {nullify})}

            send request called followup_check_sspp:
                method: "POST"
                body: "{,}"

            if not({followup_check_sspp.response.body} matches "\"statusCode\":510" or
                {followup_check_sspp.response.status_code} is "510") then
                report issue:
                    severity: high
                    confidence: firm
                    detail: `{issueDetail}`
                    remediation: `{issueRemediation}`
            end if
        end if
    end if