How to fix warning CA2100 for OLEDB connection in C#

Hakan
Hakan used Ask the Experts™
on
Hi,

I need an expert view for the below code;

     public static string ExecuteScalarSingleValue(string dbPath, string tableName, string searchTerm, string searchColumnName,  string resultColumnName)
        {
            string connectionString = null;
            string sql = null;


            connectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Mode=Read;Data Source="+ dbPath;

            
            sql = "Select ["+ resultColumnName + "] from ["+ tableName + "] Where [" + searchColumnName + "] = '" + searchTerm + "'";

            System.Data.OleDb.OleDbConnection cnn = new System.Data.OleDb.OleDbConnection(connectionString);
            try
            {
                cnn.Open();
                System.Data.OleDb.OleDbCommand cmd = new System.Data.OleDb.OleDbCommand(sql, cnn);
                // Get the value from the database
                string result = (string)cmd.ExecuteScalar();
                cmd.Dispose();
                cnn.Close();
                return result;
            }
            catch (Exception ex)
            {
                return null;
            }

        }

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It gives a warning like on attached picture.AccessWarningCA2100.png
It directs me to this page: https://docs.microsoft.com/en-us/visualstudio/code-quality/ca2100?view=vs-2019 

But i couldn't be able to fix that warning.

Any help would be grateful.
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Most Valuable Expert 2018
Distinguished Expert 2018

Commented:
Because you're manually building your SQL string, it's possible that it's vulnerable to SQL Injection. Based on your code, it's impossible to tell where the arguments that make up your query come from. If they come from user input, then it's potentially dangerous.

The suggested code fix for that is to change to using a parameterised query. This removes the risk of SQL injection. On the page you linked to, scroll down and you'll find examples of how to run your query with parameters.

However, you won't be able to use the tableName, searchColumnName or resultColumnName as parameters (that's just not how it works).

Of course, if the method arguments are coming from a know, safe call, then you can just suppress the error and move on.
ste5anSenior Developer

Commented:
By restructuring your code, e.g. this should work:

public static string ExecuteScalarSingleValue(string databaseFilename, string tableName, string searchTerm, string searchColumnName,  string resultColumnName)
{
    const string CONNECTION_STRING = "Provider=Microsoft.ACE.OLEDB.12.0;Mode=Read;Data Source={0}";
    const string COMMAND_TEXT = "SELECT [{0}] FROM [{1}] WHERE [{2}] = @searchTerm;";

    string connectionString = string.Format(CONNECTION_STRING, databaseFilename);
    using (OleDbConnection connection = new OleDbConnection(connectionString)
    {
        connection.Open();
        string commandText = string.Format(COMMAND_TEXT, resultColumnName, tableName, searchColumnName);
        using (OleDbCommand command = new OleDbCommand(commandText, connection))
        {
            command.Parameters.Add(new OleDbParameter("@searchTerm", searchTerm));
            return (string)command.ExecuteScalar();
        }
    }
}

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p.s. you method name is suboptimal. A scalar is per definition a single value. Thus the name contains a redundant part.

Author

Commented:
Hi ste5an,

Problem continues as on attachment.

@Chris Stanyon you mean there's no additional solution, if you are trust your injection just supress it?
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ste5anSenior Developer

Commented:
hmm, what VS version? What target framework? This does not raise this warning:

namespace ConsoleCS
{
    using System;
    using System.Data.OleDb;

    public class Program
    {
        public static void Main(string[] args)
        {
            Console.WriteLine(ExecuteScalarSingleValue(@"C:\Temp\myDatabase.accdb", "Table1", "1", "ID", "Payload"));

            Console.WriteLine("\nDone.");
            Console.ReadLine();
        }

        public static string ExecuteScalarSingleValue(string databaseFilename, string tableName, string searchTerm, string searchColumnName, string resultColumnName)
        {
            const string CONNECTION_STRING = "Provider=Microsoft.ACE.OLEDB.12.0;Mode=Read;Data Source={0}";
            const string COMMAND_TEXT = "SELECT [{0}] FROM [{1}] WHERE [{2}] = @searchTerm;";

            string connectionString = string.Format(CONNECTION_STRING, databaseFilename);
            using (OleDbConnection connection = new OleDbConnection(connectionString))
            {
                connection.Open();
                string commandText = string.Format(COMMAND_TEXT, resultColumnName, tableName, searchColumnName);
                using (OleDbCommand command = new OleDbCommand(commandText, connection))
                {
                    command.Parameters.Add(new OleDbParameter("@searchTerm", searchTerm));
                    return (string)command.ExecuteScalar();
                }
            }
        }
    }
}

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Author

Commented:
Hi ste5an, result is same.

I'm using VS2019, .NET4.7.2, Release-Any CPU
Most Valuable Expert 2018
Distinguished Expert 2018
Commented:
Hi Hakan,

You'll still get the same error because the error is being caused by building the commandText with arguments that are passed into the method. Although Stefan's code is using a Parameter for part of the query, the commandText is still being built with data passed in.

If you know for sure that the data your method receives (the arguments) is safe and hasn't come from some user input, then it's fine to suppress the warning.

If you don't know for sure that your arguments are safe, then you shouldn't be dynamically building your query. You would need to use a Stored Procedure to do it. This way, you wouldn't need to dynamically build your query in code, so you wouldn't raise the CA2100 warning.

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