Mini Shell

"""
This program is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License,
or (at your option) any later version.


This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
See the GNU General Public License for more details.


You should have received a copy of the GNU General Public License
 along with this program.  If not, see <https://www.gnu.org/licenses/>.

Copyright © 2019 Cloud Linux Software Inc.

This software is also available under ImunifyAV commercial license,
see <https://www.imunify360.com/legal/eula>
"""
import re
from logging import getLogger
from typing import List

from defence360agent.contracts.config import Malware as Config
from defence360agent.contracts.license import LicenseError
from defence360agent.contracts.messages import MessageType
from defence360agent.contracts.plugins import (
    MessageSink,
    MessageSource,
    expect,
)
from imav.malwarelib.utils import malware_response

logger = getLogger(__name__)


class MRSUploader(MessageSink, MessageSource):
    ERR_MSG = "Failed to submit a file"
    SUSP_PATTERN = re.compile(r"(?:suspicious\..+|[CS]MW-SUS-.+|SMW-HEUR-ELF)")

    async def create_source(self, loop, sink):
        self._sink = sink
        self._loop = loop

    async def create_sink(self, loop):
        pass

    def _separate_hits_by_type(self, results) -> tuple:
        malicious = []
        suspicious = []
        extended_suspicious = []
        for file, data in results.items():
            is_extended_suspicious = False
            is_suspicious = False
            is_malicious = False
            for hit in data["hits"]:
                is_extended_suspicious |= hit.get("extended_suspicious", False)
                is_suspicious |= bool(
                    hit["suspicious"]
                    and self.SUSP_PATTERN.match(hit["matches"])
                )
                is_malicious |= not hit["suspicious"]
            hit_info = malware_response.HitInfo(file, data["hash"])
            if is_extended_suspicious:
                extended_suspicious.append(hit_info)
            elif is_suspicious:
                suspicious.append(hit_info)
            elif is_malicious:
                malicious.append(hit_info)
        return malicious, suspicious, extended_suspicious

    @expect(MessageType.MalwareScan)
    async def process_scan(self, message):
        results = message["results"]
        if results is None:
            return
        if not Config.SEND_FILES:
            logger.info("Uploading files to MRS is disabled")
            return
        (
            malicious_hits,
            suspicious_hits,
            extended_suspicious_hits,
        ) = self._separate_hits_by_type(results)
        if malicious_hits:
            await self._sink.process_message(
                MessageType.MalwareMRSUpload(
                    hits=malicious_hits, upload_reason="malicious"
                )
            )

        if suspicious_hits:
            # Move uploading to another task
            await self._sink.process_message(
                MessageType.MalwareMRSUpload(
                    hits=suspicious_hits, upload_reason="suspicious"
                )
            )
        if extended_suspicious_hits:  # pragma: no cover
            await self._sink.process_message(
                MessageType.MalwareMRSUpload(
                    hits=extended_suspicious_hits,
                    upload_reason="extended-suspicious",
                )
            )
        errors = message["summary"].get("errors")
        if errors:
            error_hits = [
                malware_response.HitInfo(hit["file"], hit["hash"])
                for hit in errors
            ]
            await self._sink.process_message(
                MessageType.MalwareMRSUpload(
                    hits=error_hits, upload_reason="scan_error"
                )
            )

    @expect(MessageType.MalwareMRSUpload)
    async def process_hits(self, message):
        hits: List[malware_response.HitInfo] = message["hits"]
        upload_reason = message.get("upload_reason", "suspicious")

        unknown_hashes = await malware_response.check_known_hashes(
            self._loop, (hit.hash for hit in hits), upload_reason
        )
        if not unknown_hashes:
            logger.info("All files are known to MRS. Skipping uploading...")
            return

        files = (hit.file for hit in hits if hit.hash in unknown_hashes)
        for file in files:
            try:
                await malware_response.upload_with_retries(
                    file,
                    upload_reason=upload_reason,
                )
            except LicenseError as e:
                logger.warning("Cannot process message %s: %s", message, e)
                break
            except FileNotFoundError as e:
                err = "{}. {}".format(self.ERR_MSG, e.strerror)
                logger.warning("%s: %s", err, e.filename)