Description

Detects insecure wildcard (*) configurations in ASP.NET Core's AllowedHosts setting within appsettings.json files. Using a wildcard allows any host to make requests to the application, which could enable host header attacks and bypass intended access restrictions.

Detection Strategy

• Scans appsettings.json configuration files in ASP.NET Core applications

• Looks for an 'AllowedHosts' configuration key in the JSON structure

• Reports a vulnerability if the AllowedHosts value is set to wildcard '*'

• Skips analysis for files not named appsettings.json

Vulnerable code example

{
  "Logging": {
    "MinimumLevel": "Debug",  // Vulnerable: Debug level exposes sensitive details in production
    "LogLevel": {
      "Default": "Debug",
      "System": "Debug",
      "Microsoft": "Debug"    // Dangerous: Logs detailed system/framework information
    }...

✅ Secure code example

{
  "Logging": {
    "MinimumLevel": "Information",  // Secure: Only logs necessary operational info, not debug details
    "LogLevel": {
      "Default": "Information",
      "System": "Warning",
      "Microsoft": "Warning"    // Secure: Restricts framework logging to warnings only
    }...