robsware

The vulnerability is Incorrect Default Permissions

csharp
// Vulnerable code
using System.IO;

class IncorrectDefaults
{
    static void Main()
    {
        FileStream fs = new FileStream("importantData.txt", FileMode.Create);

        using (StreamWriter sw = new StreamWriter(fs))
        {
            sw.WriteLine("Sensitive Data");
        }
    }
}

csharp // Vulnerable code using System.IO; class IncorrectDefaults { static void Main() { FileStream fs = new FileStream("importantData.txt", FileMode.Create); using (StreamWriter sw = new StreamWriter(fs)) { sw.WriteLine("Sensitive Data"); } } } - Use `File.GetAccessControl()` method to get the access control object for the file. - Call `SetAccessRuleProtection(true, false)` on the file security object to disable inheritance and remove inherited access rules. - Create a new access rule for the current user allowing Read and Write permissions. - Set the new access rule using the `SetAccessRule()` method. - Apply the modified access control settings to the file using `File.SetAccessControl()`.

csharp
// Fixed code
using System.IO;
using System.Security.AccessControl;

class CorrectDefaults
{
    static void Main()
    {
        string filePath = "importantData.txt";
        FileStream fs = new FileStream(filePath, FileMode.Create);

        // Set file permission to read and write only for the current user
        FileSecurity fileSec = File.GetAccessControl(filePath);
        fileSec.SetAccessRuleProtection(true, false); // Disable inheritance, remove inherited access rules
        FileSystemAccessRule accessRule = new FileSystemAccessRule(Environment.UserName, FileSystemRights.Read | FileSystemRights.Write, AccessControlType.Allow);
        fileSec.SetAccessRule(accessRule);
        File.SetAccessControl(filePath, fileSec);

        using (StreamWriter sw = new StreamWriter(fs))
        {
            sw.WriteLine("Sensitive Data");
        }
    }
}