Python API (havoc-py)

The havoc-py library provides a Python interface to Havoc’s Service API, enabling custom agent development, automation, and extensibility.

Installation

git clone https://github.com/HavocFramework/havoc-py
cd havoc-py
pip install .

The havoc-py library requires Python 3.8 or higher.

Core Classes

HavocService

Manages the WebSocket connection to the Teamserver Service API.

Constructor

from havoc.service import HavocService

havoc = HavocService(
    endpoint="ws://0.0.0.0:40056/service-endpoint",
    password="service-password"
)

endpoint

string

required

WebSocket URL to the Teamserver Service endpoint

password

string

required

Service password (defined in Teamserver profile)

Methods

register_agent

method

havoc.register_agent(agent: AgentType) -> None

Parameters:

agent (AgentType): Agent instance to register

Example:

from havoc.agent import AgentType

agent = MyCustomAgent()
havoc.register_agent(agent)

register_externalc2

method

await havoc.register_externalc2(
    name: str,
    endpoint: str
) -> dict

Parameters:

name (str): Display name for the External C2
endpoint (str): HTTP endpoint path for agent traffic

Returns: Registration response dictionaryExample:

response = await havoc.register_externalc2(
    name="DNS-C2",
    endpoint="dns-transport"
)

AgentType

Base class for defining custom agent types.

Class Attributes

from havoc.agent import AgentType

class MyAgent(AgentType):
    Name = "MyAgent"                 # Agent name displayed in UI
    Author = "@YourHandle"           # Attribution
    Version = "1.0"                  # Version string
    Description = "Custom agent"     # Brief description
    MagicValue = 0xDEADBEEF         # Unique identifier (hex)
    
    Formats = [                      # Supported output formats
        {
            "Name": "Executable",
            "Extension": "exe"
        }
    ]
    
    SupportedOS = [                  # Operating systems
        "Windows",
        "Linux",
        "MacOS"
    ]
    
    BuildingConfig = {               # Build options (shown in UI)
        "Sleep": "5",
        "Jitter": "10",
        "Host": "0.0.0.0",
        "Port": "443"
    }
    
    Commands = []                    # List of Command instances

Name

string

required

Agent name displayed in the Havoc UI

Author

string

required

Author attribution (e.g., “@username”)

Version

string

required

Version string (e.g., “1.0.0”)

Description

string

required

Brief description of the agent’s purpose

MagicValue

integer

required

Unique identifier for the agent type (hexadecimal)

Formats

list

required

List of supported payload formats

[
    {"Name": "Executable", "Extension": "exe"},
    {"Name": "Shellcode", "Extension": "bin"}
]

SupportedOS

list

required

List of supported operating systems: "Windows", "Linux", "MacOS"

BuildingConfig

dict

required

Configuration options displayed in the payload generation UI

{
    "Sleep": "5",
    "Jitter": "10",
    "CustomOption": "value"
}

Commands

list

required

List of Command instances defining available commands

Methods

generate

method

Generate the agent payload.

def generate(self, config: dict) -> str:
    """
    Args:
        config: BuildingConfig values from UI
    
    Returns:
        Generated payload as string or bytes
    """
    pass

Example:

def generate(self, config: dict) -> str:
    with open('agent_template.py', 'r') as f:
        template = f.read()
    
    # Replace placeholders
    payload = template.replace('{{SLEEP}}', config['Sleep'])
    payload = payload.replace('{{HOST}}', config['Host'])
    
    return payload

Command

Defines a custom command for your agent.

Class Attributes

from havoc.agent import Command, CommandParam
from havoc.packer import Packer

class CommandShell(Command):
    CommandId = 0x100                      # Unique command ID
    Name = "shell"                         # Command name
    Description = "Execute shell command"  # Brief description
    Help = "shell <command>"               # Usage help text
    NeedAdmin = False                      # Requires admin privileges
    Mitr = ["T1059", "T1059.001"]         # MITRE ATT&CK techniques
    
    Params = [                             # Command parameters
        CommandParam(
            name="command",
            is_file_path=False,
            is_optional=False
        )
    ]
    
    def job_generate(self, arguments: dict) -> bytes:
        packer = Packer()
        packer.add_int(self.CommandId)
        packer.add_data(arguments['command'])
        return packer.buffer

CommandId

integer

required

Unique identifier for the command (e.g., 0x100)

Name

string

required

Command name as typed in the console

Description

string

required

Brief description shown in help text

Help

string

required

Detailed usage information

NeedAdmin

boolean

required

Whether command requires administrator/root privileges

Mitr

list

required

List of MITRE ATT&CK technique IDs (e.g., ["T1059"])

Params

list

required

List of CommandParam instances defining parameters

Methods

job_generate

method

Generate the binary command payload.

def job_generate(self, arguments: dict) -> bytes:
    """
    Args:
        arguments: Dictionary with parameter values
    
    Returns:
        Packed binary command data
    """
    pass

Example:

def job_generate(self, arguments: dict) -> bytes:
    packer = Packer()
    
    # Pack command ID
    packer.add_int(self.CommandId)
    
    # Pack parameters
    packer.add_data(arguments['command'])
    
    return packer.buffer

CommandParam

Defines a command parameter.

Constructor

from havoc.agent import CommandParam

# String parameter
param = CommandParam(
    name="message",
    is_file_path=False,
    is_optional=False
)

# File path parameter (shows file picker in UI)
param = CommandParam(
    name="local_file",
    is_file_path=True,
    is_optional=False
)

# Optional parameter
param = CommandParam(
    name="timeout",
    is_file_path=False,
    is_optional=True
)

name

string

required

Parameter name (referenced in arguments dict)

is_file_path

boolean

required

If True, UI shows file picker. If False, shows text input.

is_optional

boolean

required

Whether parameter is optional

Packer

Utility class for building binary command payloads.

Methods

add_int

method

Add a 32-bit integer (little-endian).

packer.add_int(value: int) -> None

Example:

packer.add_int(0x100)  # Command ID
packer.add_int(42)     # Numeric value

add_data

method

Add a null-terminated string.

packer.add_data(data: str) -> None

Example:

packer.add_data("whoami")
packer.add_data("/etc/passwd")

add_bytes

method

Add raw bytes.

packer.add_bytes(data: bytes) -> None

Example:

packer.add_bytes(b"\x00\x01\x02\x03")
packer.add_bytes(file_contents)

buffer

property

Get the packed binary data.

command_bytes = packer.buffer

Returns: bytes object with packed data

Complete Examples

Basic Shell Command

shell_command.py

from havoc.agent import Command, CommandParam
from havoc.packer import Packer

COMMAND_SHELL = 0x100

class CommandShell(Command):
    CommandId = COMMAND_SHELL
    Name = "shell"
    Description = "Execute shell commands using /bin/sh"
    Help = """
    Usage: shell <command>
    
    Executes the specified command using the system shell.
    
    Examples:
        shell whoami
        shell cat /etc/passwd
        shell ls -la /tmp
    """
    NeedAdmin = False
    Mitr = ["T1059", "T1059.004"]  # Command and Scripting Interpreter: Unix Shell
    
    Params = [
        CommandParam(
            name="command",
            is_file_path=False,
            is_optional=False
        )
    ]
    
    def job_generate(self, arguments: dict) -> bytes:
        packer = Packer()
        packer.add_int(self.CommandId)
        packer.add_data(arguments['command'])
        return packer.buffer

File Upload Command

upload_command.py

from havoc.agent import Command, CommandParam
from havoc.packer import Packer
import os

COMMAND_UPLOAD = 0x101

class CommandUpload(Command):
    CommandId = COMMAND_UPLOAD
    Name = "upload"
    Description = "Upload file to target"
    Help = """
    Usage: upload <local_file> <remote_path>
    
    Uploads a file from the operator's system to the target.
    
    Examples:
        upload /tmp/tool.sh /tmp/tool.sh
        upload implant.elf /var/tmp/.hidden
    """
    NeedAdmin = False
    Mitr = ["T1105"]  # Ingress Tool Transfer
    
    Params = [
        CommandParam(
            name="local_file",
            is_file_path=True,
            is_optional=False
        ),
        CommandParam(
            name="remote_path",
            is_file_path=False,
            is_optional=False
        )
    ]
    
    def job_generate(self, arguments: dict) -> bytes:
        packer = Packer()
        
        # Command ID
        packer.add_int(self.CommandId)
        
        # Remote path
        packer.add_data(arguments['remote_path'])
        
        # Read file
        with open(arguments['local_file'], 'rb') as f:
            file_data = f.read()
        
        # File size
        packer.add_int(len(file_data))
        
        # File contents
        packer.add_bytes(file_data)
        
        return packer.buffer

Complete Agent Example

from havoc.agent import AgentType
from commands import CommandShell, CommandPwd, CommandUpload, CommandDownload

class TalonAgent(AgentType):
    Name = "Talon"
    Author = "@HavocFramework"
    Version = "0.1.0"
    Description = "Python-based cross-platform agent"
    MagicValue = 0x5041594C
    
    Formats = [
        {
            "Name": "Python Script",
            "Extension": "py"
        },
        {
            "Name": "PyInstaller Executable",
            "Extension": "exe"
        }
    ]
    
    SupportedOS = [
        "Linux",
        "MacOS",
        "Windows"
    ]
    
    BuildingConfig = {
        "Sleep": "5",
        "Jitter": "20",
        "Host": "0.0.0.0",
        "Port": "443",
        "UserAgent": "Mozilla/5.0",
        "Secure": "true"
    }
    
    Commands = [
        CommandShell(),
        CommandPwd(),
        CommandUpload(),
        CommandDownload()
    ]
    
    def generate(self, config: dict) -> str:
        # Load template
        with open('templates/agent.py.template', 'r') as f:
            template = f.read()
        
        # Replace placeholders
        replacements = {
            '{{SLEEP}}': config['Sleep'],
            '{{JITTER}}': config['Jitter'],
            '{{HOST}}': config['Host'],
            '{{PORT}}': config['Port'],
            '{{USER_AGENT}}': config['UserAgent'],
            '{{SECURE}}': config['Secure']
        }
        
        payload = template
        for key, value in replacements.items():
            payload = payload.replace(key, value)
        
        return payload

Service API Protocol

Authentication

import json
import hashlib

def authenticate(websocket, password):
    # Hash password with SHA3-256
    hasher = hashlib.sha3_256()
    hasher.update(password.encode())
    hashed = hasher.hexdigest()
    
    # Send auth message
    auth_msg = {
        "Head": {"Type": "Register"},
        "Body": {"Password": password}
    }
    websocket.send(json.dumps(auth_msg))
    
    # Receive response
    response = json.loads(websocket.recv())
    return response["Body"]["Success"]

Message Types

RegisterAgent
AgentRegister
AgentTask
AgentOutput

message = {
    "Head": {
        "Type": "RegisterAgent"
    },
    "Body": {
        "Agent": {
            "Name": "MyAgent",
            "Author": "@me",
            "Version": "1.0",
            "MagicValue": "deadbeef",
            # ... other agent properties
        }
    }
}

message = {
    "Head": {"Type": "Agent"},
    "Body": {
        "Type": "AgentRegister",
        "AgentHeader": {
            "Size": "1024",
            "MagicValue": "deadbeef",
            "AgentID": "12345678"
        },
        "RegisterInfo": {
            "Hostname": "target-host",
            "Username": "user",
            "DomainName": "WORKGROUP",
            "InternalIP": "192.168.1.100",
            "Process Name": "python3",
            "Process ID": "1234",
            "OS Version": "Linux 5.15",
            "OS Arch": "x64"
        }
    }
}

# Request tasks
message = {
    "Head": {"Type": "Agent"},
    "Body": {
        "Type": "AgentTask",
        "Agent": {"NameID": "agent-12345"},
        "Task": "Get"
    }
}

import base64

message = {
    "Head": {"Type": "Agent"},
    "Body": {
        "Type": "AgentOutput",
        "AgentID": "agent-12345",
        "Callback": {
            "Type": "Output",
            "Message": "Command output here"
        }
    }
}

Best Practices

Command IDs

Use unique command IDs starting from 0x100
Reserve 0x00-0xFF for system commands
Document your ID allocation scheme
Avoid ID conflicts between commands

Parameter Validation

def job_generate(self, arguments: dict) -> bytes:
    # Validate required parameters
    if 'command' not in arguments:
        raise ValueError("Missing required parameter: command")
    
    # Validate parameter types
    if not isinstance(arguments['command'], str):
        raise TypeError("Parameter 'command' must be string")
    
    # Sanitize inputs
    command = arguments['command'].strip()
    if not command:
        raise ValueError("Parameter 'command' cannot be empty")
    
    # Generate command
    packer = Packer()
    packer.add_int(self.CommandId)
    packer.add_data(command)
    return packer.buffer

Error Handling

def generate(self, config: dict) -> str:
    try:
        # Attempt payload generation
        payload = self._build_payload(config)
        return payload
    except FileNotFoundError as e:
        raise RuntimeError(f"Template not found: {e}")
    except Exception as e:
        raise RuntimeError(f"Payload generation failed: {e}")

Logging

import logging

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

class MyAgent(AgentType):
    def generate(self, config: dict) -> str:
        logger.info(f"Generating payload with config: {config}")
        # ...
        logger.info("Payload generated successfully")
        return payload

Resources

havoc-py Repository

Official Python API source code

Talon Example

Reference implementation using havoc-py

Custom Agents Guide

Step-by-step agent development

External C2 Guide

Using havoc-py for External C2

Get Started

Core Concepts

Demon Agent

Listeners

Extensibility

Advanced

Installation

Core Classes

HavocService

Constructor

Methods

AgentType

Class Attributes

Methods

Command

Class Attributes

Methods

CommandParam

Constructor

Packer

Methods

Complete Examples

Basic Shell Command

File Upload Command

Complete Agent Example

Service API Protocol

Authentication

Message Types

Best Practices

Resources

havoc-py Repository

Talon Example

Custom Agents Guide

External C2 Guide

Build docs developers (and LLMs) love

Get Started

Core Concepts

Demon Agent

Listeners

Extensibility

Advanced

Documentation Index

​Installation

​Core Classes

​HavocService

​Constructor

​Methods

​AgentType

​Class Attributes

​Methods

​Command

​Class Attributes

​Methods

​CommandParam

​Constructor

​Packer

​Methods

​Complete Examples

​Basic Shell Command

​File Upload Command

​Complete Agent Example

​Service API Protocol

​Authentication

​Message Types

​Best Practices

​Resources

havoc-py Repository

Talon Example

Custom Agents Guide

External C2 Guide

Build docs developers (and LLMs) love

Installation

Core Classes

HavocService

Constructor

Methods

AgentType

Class Attributes

Methods

Command

Class Attributes

Methods

CommandParam

Constructor

Packer

Methods

Complete Examples

Basic Shell Command

File Upload Command

Complete Agent Example

Service API Protocol

Authentication

Message Types

Best Practices

Resources