LSMS/scripts/monitor_ld_preload.py
2022-01-05 20:16:57 +01:00

111 lines
2.6 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/ld.so.preload for changes to detect malicious attempts to alter the control flow of binaries.
Requirements:
None
"""
import os
from typing import Set
from lib.state import load_state, store_state
from lib.util import output_error, output_finding
# Read configuration.
try:
from config.config import ALERTR_FIFO, FROM_ADDR, TO_ADDR, STATE_DIR
from config.monitor_ld_preload 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__))
def _get_ld_preload() -> Set[str]:
path = "/etc/ld.so.preload"
ld_data = set()
if os.path.isfile(path):
with open(path, 'rt') as fp:
for line in fp:
if line.strip() == "":
continue
ld_data.add(line.strip())
return ld_data
def monitor_ld_preload():
# 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_ld_data = set()
try:
state_data = load_state(STATE_DIR)
# Convert list to set.
if "ld_data" in state_data.keys():
stored_ld_data = set(state_data["ld_data"])
except Exception as e:
output_error(__file__, str(e))
return
curr_ld_data = set()
try:
curr_ld_data = _get_ld_preload()
except Exception as e:
output_error(__file__, str(e))
return
# Compare stored data with current one.
for stored_entry in stored_ld_data:
if stored_entry not in curr_ld_data:
message = "LD_PRELOAD entry '%s' was deleted." % stored_entry
output_finding(__file__, message)
continue
# Check new data was added.
for curr_entry in curr_ld_data:
if curr_entry not in stored_ld_data:
message = "LD_PRELOAD entry '%s' was added." % curr_entry
output_finding(__file__, message)
try:
# Convert set to list.
state_data = {"ld_data": list(curr_ld_data)}
store_state(STATE_DIR, state_data)
except Exception as e:
output_error(__file__, str(e))
if __name__ == '__main__':
monitor_ld_preload()