Worker Plugins

Overview

Worker plugins are the primary data producers within stoQ. These plugins allow for tasks such as scanning payloads with yara, hashing payloads, and even extracting indicators of compromise (IOC) from documents. Worker plugins can be defined in all scanning modes. Additionally worker plugins can be dynamically loaded using dispatching plugins. More information on dispatcher plugins can be found in the dispatcher plugin section.

Worker plugins can be defined multiple ways. In these examples, we will use the hash worker plugin.

From the command line, worker plugins can be defined two different ways, depending on the use.

If only the original payload must be scanned, then --start-dispatch or -s command line argument may be used.:

$ stoq scan -s hash [...]

However, if the original payload and all subsequent payloads must be scanned, the --always-dispatch or -a command line argument may be used:

$ stoq scan -a hash [...]

Note

The difference between --start-dispatch and --always-dispatch can be somewhat confusing. The primary difference between the two is that if a worker plugin extracts any payloads for further scanning, any extracted payloads will only be scanned by workers defined by --always-dispatch. If --start-dispatch was used, the plugin defined will not be used to scan any extracted payloads.

Or, when instantiating the Stoq() class:

>>> import stoq
>>> workers= ['yara']
>>> s = Stoq(always_dispatch=workers, [...])

Lastly, worker plugins can be defined by dispatcher plugins. As mentioned previously, more information on them can be found in the dispatcher plugin section

Writing a plugin

A worker plugin must be a subclass of the WorkerPlugin class.

As with any plugin, a configuration file must also exist and be properly configured.

Example

from typing import Dict, List, Optional
from configparser import ConfigParser

from stoq.data_classes import (
    Payload,
    RequestMeta,
    WorkerResponse,
)
from stoq.plugins import WorkerPlugin


class ExampleWorker(WorkerPlugin):
    def __init__(self, config: ConfigParser, plugin_opts: Optional[Dict]) -> None:
        super().__init__(config, plugin_opts)
        self.useful = config.get('options', 'useful', fallback=False)

    def scan(
        self, payload: Payload, request_meta: RequestMeta
    ) -> Optional[WorkerResponse]:
        if self.useful:
            wr = WorkerResponse({'worker_results': 'something useful'})
        else:
            wr = WorkerResponse({'worker_results': 'something not useful'})
        return wr

Extracted Payloads

Worker plugins may also extract payloads, and return them to Stoq for further analysis. Each extracted payload that is returned will be inserted into the same workflow as the original payload.

from typing import Dict, List, Optional
from configparser import ConfigParser

from stoq.data_classes import (
    ExtractedPayload,
    Payload,
    PayloadMeta,
    RequestMeta,
    WorkerResponse,
)
from stoq.plugins import WorkerPlugin


class ExampleWorker(WorkerPlugin):
    def __init__(self, config: ConfigParser, plugin_opts: Optional[Dict]) -> None:
        super().__init__(config, plugin_opts)
        self.useful = config.get('options', 'useful', fallback=False)

    def scan(
        self, payload: Payload, request_meta: RequestMeta
    ) -> Optional[WorkerResponse]:
        p = ExtractedPayload(b'Lorem ipsum')
        if self.useful:
            wr = WorkerResponse({'worker_results': 'something useful'}, extracted=[p])
        else:
            wr = WorkerResponse({'worker_results': 'something not useful'}, extracted=[p])
        return wr

Dispatch To

In some cases it may be useful for a worker plugin to dicate which plugins an extracted payload is scanned with.

from typing import Dict, List, Optional
from configparser import ConfigParser

from stoq.data_classes import (
    ExtractedPayload,
    Payload,
    PayloadMeta,
    RequestMeta,
    WorkerResponse,
)
from stoq.plugins import WorkerPlugin


class ExampleWorker(WorkerPlugin):
    def __init__(self, config: ConfigParser, plugin_opts: Optional[Dict]) -> None:
        super().__init__(config, plugin_opts)
        self.useful = config.get('options', 'useful', fallback=False)

    def scan(
        self, payload: Payload, request_meta: RequestMeta
    ) -> Optional[WorkerResponse]:
        dispatch_meta = PayloadMeta(dispatch_to='yara')
        p = ExtractedPayload(b'this is a payload with bad stuff', dispatch_meta)
        if self.useful:
            wr = WorkerResponse({'worker_results': 'something useful'}, extracted=[p])
        else:
            wr = WorkerResponse({'worker_results': 'something not useful'}, extracted=[p])
        return wr

API

class stoq.plugins.worker.WorkerPlugin(config, plugin_opts)

scan(payload, request_meta)

Return type:Optional[WorkerResponse]

Response

class stoq.data_classes.WorkerResponse(results=None, extracted=None, errors=None)

Object containing response from worker plugins

Parameters:

• results (Optional[Dict[~KT, ~VT]]) – Results from worker scan
• extracted (Optional[List[ExtractedPayload]]) – ExtractedPayload object of extracted payloads from scan
• errors (Optional[List[str]]) – Errors that occurred

>>> results = {'is_bad': True, 'filetype': 'executable'}
>>> extracted_payload = ExtractedPayload(content=data, payload_meta=extracted_meta)
>>> response = WorkerResponse(results=results, extracted=[extracted_payload])