AzureC2Relay : An Azure Function That Validates And Relays Cobalt Strike Beacon

AzureC2Relay is an Azure Function that validates and relays Cobalt Strike beacon traffic by verifying the incoming requests based on a Cobalt Strike Malleable C2 profile. Any incoming requests that do not share the profiles user-agent, URI paths, headers, and query parameters, will be redirected to a configurable decoy website.

The validated C2 traffic is relayed to a team server within the same virtual network that is further restricted by a network security group. Allowing the VM to only expose SSH.

Deploy

• AzureC2Relay is deployed via terraform azure modules as well as some local az cli commands
• Make sure you have terraform , az cli and the dotnet core 3.1 runtime installed
• Windows (Powershell)

&([scriptblock]::Create((Invoke-WebRequest -UseBasicParsing ‘https://dot.net/v1/dotnet-install.ps1’))) -runtime dotnet -version 3.1.0
Invoke-WebRequest ‘https://releases.hashicorp.com/terraform/0.14.6/terraform_0.14.6_windows_amd64.zip’ -OutFile ‘terraform.zip’
Expand-Archive -Path terraform.zip -DestinationPath “$([Environment]::GetFolderPath(‘ApplicationData’))\TerraForm\”
setx PATH “%PATH%;$([Environment]::GetFolderPath(‘ApplicationData’))\TerraForm\”
Invoke-WebRequest -Uri https://aka.ms/installazurecliwindows -OutFile .\AzureCLI.msi; Start-Process msiexec.exe -Wait -ArgumentList ‘/I AzureCLI.msi /quiet’; rm .\AzureCLI.msi

• Mac

curl -L https://dot.net/v1/dotnet-install.sh | bash -s — –runtime dotnet –version 3.1.0
brew update
brew tap hashicorp/tap
brew install hashicorp/tap/terraform
brew install azure-cli

• Ubuntu , Debian

curl -L https://dot.net/v1/dotnet-install.sh | bash -s — –runtime dotnet –version 3.1.0
wget https://releases.hashicorp.com/terraform/0.14.5/terraform_0.14.5_linux_amd64.zip
unzip terraform_0.14.5_linux_amd64.zip
sudo cp terraform /usr/local/bin/terraform
curl -sL https://aka.ms/InstallAzureCLIDeb | sudo bash

• Kali

curl -L https://dot.net/v1/dotnet-install.sh | bash -s — –runtime dotnet –version 3.1.0
wget https://releases.hashicorp.com/terraform/0.14.5/terraform_0.14.5_linux_amd64.zip
unzip terraform_0.14.5_linux_amd64.zip
sudo cp terraform /usr/local/bin/terraform
echo “deb [arch=amd64] https://packages.microsoft.com/repos/azure-cli/ stretch main” | sudo tee /etc/apt/sources.list.d/azure-cli.list
curl -L https://packages.microsoft.com/keys/microsoft.asc | sudo apt-key add –
sudo apt-get update && sudo apt-get install apt-transport-https azure-cli

• Modify the first variables defined in config.tf to suit your needs
• Replace the dummy “cobaltstrike-dist.tgz” with an actual cobaltstrike download
• Edit/Replace the Malleable profile inside the Ressources folder (Make sure the profile filename matches the variables you set in step 1)
• login with azure az login
• run terraform init
• run terraform apply -auto-approve to deploy the infra
• Wait for the CDN to become active and enjoy!

Once terraform completes it will provide you with the needed ssh command, the CobaltStrike teamserver will be running inside an tmux session on the deployed VM

When your done using the infra, you can remove it with terraform destroy -auto-approve