xeca
xeca is a project that creates encrypted PowerShell payloads for offensive purposes.
Creating position independent shellcode from DLL files is also possible.
Note: Please place your custom AMSI bypass in src/assets/amsi-bypass.ps1.
Install
Firstly ensure that rust is installed, then build the project with the following command:
cargo build
How It Works
- Identify and encrypt the payload. Load encrypted payload into a powershell script and save to a file named “launch.txt”
- The key to decrypt the payload is saved to a file named “safe.txt”
- Execute “launch.txt” on a remote host
- The script will call back to the attacker defined web server to retrieve the decryption key “safe.txt”
- Decrypt the payload in memory
- Execute the intended payload in memory
Mitigations
If users must have access to programs such as powershell.exe, consider minimising security risks with Just Enough Administration and PowerShell Logging. Application control policies can be deployed via a whitelisting technology such as AppLocker.
Examples
Covenant
Covenant .NET assembly donut payload.
Acknowledgements
This tool would not be possible without the sharing of knowledge and information. Ideas, snippets and code from the following authors should be acknowledged:
@monoxgas
@H0neyBadger
@TheWover
@stephenfewer
@dismantl
@tandasat
@cobbr
License
xeca is licensed under GPLv3, some sub-components may have separate licenses. See their respective references in this project for details.