rspec/rules/S2078/csharp/rule.adoc

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== Noncompliant Code Example

----
using System.DirectoryServices;
using Microsoft.AspNetCore.Mvc;

namespace WebApplicationDotNetCore.Controllers
{
    public class RSPEC2078LDAPInjectionNoncompliantController : Controller
    {
        public IActionResult Index()
        {
            return View();
        }

        public DirectorySearcher ds { get; set; }

        public IActionResult Authenticate(string user, string pass)
        {
            ds.Filter = "(&(uid=" + user + ")(userPassword=" + pass + "))"; // Noncompliant

            // If the special value "*)(uid=*))(|(uid=*" is passed as user, authentication is bypassed
            // Indeed, if it is passed as a user, the filter becomes:
            // (&(uid=*)(uid=*))(|(uid=*)(userPassword=...))
            // as uid=* match all users, it is equivalent to:
            // (|(uid=*)(userPassword=...))
            // again, as uid=* match all users, the filter becomes useless

            return Content(ds.FindOne() != null ? "success" : "fail");
        }
    }
}
----

== Compliant Solution

----
using System.DirectoryServices;
using System.Text.RegularExpressions;
using Microsoft.AspNetCore.Mvc;

namespace WebApplicationDotNetCore.Controllers
{
    public class RSPEC2078LDAPInjectionCompliantController : Controller
    {
        public IActionResult Index()
        {
            return View();
        }

        public DirectorySearcher ds { get; set; }

        public IActionResult Authenticate(string user, string pass)
        {
            // restrict the username and password to letters only
            if (!Regex.IsMatch(user, "^[a-zA-Z]+$") || !Regex.IsMatch(pass, "^[a-zA-Z]+$"))
            {
                return BadRequest();
            }

            ds.Filter = "(&(uid=" + user + ")(userPassword=" + pass + "))"; // Now safe
            return Content(ds.FindOne() != null ? "success" : "fail");
        }
    }
}
----

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== Comments And Links
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