LSMS/scripts/monitor_hosts_file.py
Andre Pawlowski 0b7ed4177a fixed comment
2021-12-30 20:48:17 +01:00

301 lines
8.9 KiB
Python
Executable file

#!/usr/bin/env python3
# written by sqall
# twitter: https://twitter.com/sqall01
# blog: https://h4des.org
# github: https://github.com/sqall01
#
# Licensed under the MIT License.
"""
Short summary:
Monitor /etc/hosts for changes to detect malicious attempts to divert traffic.
Requirements:
None
"""
import os
import json
import socket
import stat
from typing import Dict, Set
from lib.alerts import raise_alert_alertr, raise_alert_mail
# Read configuration and library functions.
try:
from config.config import ALERTR_FIFO, FROM_ADDR, TO_ADDR, STATE_DIR
from config.monitor_hosts_file import ACTIVATED
STATE_DIR = os.path.join(os.path.dirname(__file__), STATE_DIR, os.path.basename(__file__))
except:
ALERTR_FIFO = None
FROM_ADDR = None
TO_ADDR = None
ACTIVATED = True
STATE_DIR = os.path.join("/tmp", os.path.basename(__file__))
MAIL_SUBJECT = "[Security] Monitoring /etc/hosts on host '%s'" % socket.gethostname()
class MonitorHostsException(Exception):
def __init__(self, msg: str):
self._msg = msg
def __str__(self):
return self._msg
def _get_hosts() -> Dict[str, Set[str]]:
hosts_data = {}
with open("/etc/hosts", 'rt') as fp:
for line in fp:
line = line.strip()
if line == "":
continue
# Ignore comments.
if line[0] == "#":
continue
entry = line.split()
if len(entry) < 2:
raise MonitorHostsException("Not able to parse line: %s" % line)
ip = entry[0]
hosts = set(entry[1:])
if ip not in hosts_data.keys():
hosts_data[ip] = hosts
else:
for host in hosts:
hosts_data[ip].add(host)
return hosts_data
def _load_hosts_data() -> Dict[str, Set[str]]:
state_file = os.path.join(STATE_DIR, "state")
hosts_data = {}
if os.path.isfile(state_file):
data = None
try:
with open(state_file, 'rt') as fp:
data = fp.read()
if data is None:
raise MonitorHostsException("Read state data is None.")
temp = json.loads(data)
# Convert list to set.
for k,v in temp.items():
hosts_data[k] = set(v)
except Exception as e:
raise MonitorHostsException("State data: '%s'; Exception: '%s'" % (str(data), str(e)))
return hosts_data
def _output_error(msg: str):
# Decide where to output results.
print_output = False
if ALERTR_FIFO is None and FROM_ADDR is None and TO_ADDR is None:
print_output = True
if print_output:
print(msg)
else:
hostname = socket.gethostname()
message = "Error monitoring /etc/hosts on host '%s': %s" \
% (hostname, msg)
if ALERTR_FIFO:
optional_data = dict()
optional_data["error"] = True
optional_data["message"] = message
raise_alert_alertr(ALERTR_FIFO,
optional_data)
if FROM_ADDR is not None and TO_ADDR is not None:
raise_alert_mail(FROM_ADDR,
TO_ADDR,
MAIL_SUBJECT,
message)
def _store_hosts_data(hosts_data: Dict[str, Set[str]]):
# Create state dir if it does not exist.
if not os.path.exists(STATE_DIR):
os.makedirs(STATE_DIR)
state_file = os.path.join(STATE_DIR, "state")
# Convert set to list.
temp = {}
for k, v in hosts_data.items():
temp[k] = list(v)
with open(state_file, 'wt') as fp:
fp.write(json.dumps(temp))
os.chmod(state_file, stat.S_IREAD | stat.S_IWRITE)
def monitor_hosts():
# Decide where to output results.
print_output = False
if ALERTR_FIFO is None and FROM_ADDR is None and TO_ADDR is None:
print_output = True
if not ACTIVATED:
if print_output:
print("Module deactivated.")
return
stored_hosts_data = {}
try:
stored_hosts_data =_load_hosts_data()
except Exception as e:
_output_error(str(e))
return
curr_hosts_data = {}
try:
curr_hosts_data = _get_hosts()
except Exception as e:
_output_error(str(e))
return
# Compare stored data with current one.
for stored_entry_ip in stored_hosts_data.keys():
# Extract current entry belonging to the same ip.
if stored_entry_ip not in curr_hosts_data.keys():
hostname = socket.gethostname()
message = "Host name for IP '%s' was deleted on host '%s'." \
% (stored_entry_ip, hostname)
if print_output:
print(message)
print("#" * 80)
if ALERTR_FIFO:
optional_data = dict()
optional_data["ip"] = stored_entry_ip
optional_data["hostname"] = hostname
optional_data["message"] = message
raise_alert_alertr(ALERTR_FIFO,
optional_data)
if FROM_ADDR is not None and TO_ADDR is not None:
raise_alert_mail(FROM_ADDR,
TO_ADDR,
MAIL_SUBJECT,
message)
continue
# Check host entry was removed.
for host in stored_hosts_data[stored_entry_ip]:
if host not in curr_hosts_data[stored_entry_ip]:
hostname = socket.gethostname()
message = "Host name entry for IP '%s' was removed on host '%s'.\n\n" % (stored_entry_ip, hostname)
message += "Entry: %s" % host
if print_output:
print(message)
print("#" * 80)
if ALERTR_FIFO:
optional_data = dict()
optional_data["ip"] = stored_entry_ip
optional_data["host_entry"] = host
optional_data["hostname"] = hostname
optional_data["message"] = message
raise_alert_alertr(ALERTR_FIFO,
optional_data)
if FROM_ADDR is not None and TO_ADDR is not None:
raise_alert_mail(FROM_ADDR,
TO_ADDR,
MAIL_SUBJECT,
message)
# Check host entry was added.
for host in curr_hosts_data[stored_entry_ip]:
if host not in stored_hosts_data[stored_entry_ip]:
hostname = socket.gethostname()
message = "Host name entry for IP '%s' was added on host '%s'.\n\n" % (stored_entry_ip, hostname)
message += "Entry: %s" % host
if print_output:
print(message)
print("#" * 80)
if ALERTR_FIFO:
optional_data = dict()
optional_data["ip"] = stored_entry_ip
optional_data["host_entry"] = host
optional_data["hostname"] = hostname
optional_data["message"] = message
raise_alert_alertr(ALERTR_FIFO,
optional_data)
if FROM_ADDR is not None and TO_ADDR is not None:
raise_alert_mail(FROM_ADDR,
TO_ADDR,
MAIL_SUBJECT,
message)
# Check new data was added.
for curr_entry_ip in curr_hosts_data.keys():
if curr_entry_ip not in stored_hosts_data.keys():
hostname = socket.gethostname()
message = "New host name was added for IP '%s' on host '%s'.\n\n" \
% (curr_entry_ip, hostname)
message += "Entries:\n"
for host in curr_hosts_data[curr_entry_ip]:
message += host
message += "\n"
if print_output:
print(message)
print("#" * 80)
if ALERTR_FIFO:
optional_data = dict()
optional_data["ip"] = curr_entry_ip
optional_data["hosts"] = list(curr_hosts_data[curr_entry_ip])
optional_data["hostname"] = hostname
optional_data["message"] = message
raise_alert_alertr(ALERTR_FIFO,
optional_data)
if FROM_ADDR is not None and TO_ADDR is not None:
raise_alert_mail(FROM_ADDR,
TO_ADDR,
MAIL_SUBJECT,
message)
try:
_store_hosts_data(curr_hosts_data)
except Exception as e:
_output_error(str(e))
if __name__ == '__main__':
monitor_hosts()