177 lines
7.3 KiB
Python
177 lines
7.3 KiB
Python
#!/usr/bin/env python3
|
|
# -*- coding: utf-8 -*-
|
|
|
|
from pathlib import Path
|
|
from datetime import datetime
|
|
from impacket.ldap import ldap, ldapasn1
|
|
from impacket.ldap.ldap import LDAPSearchError
|
|
|
|
|
|
class CMEModule:
|
|
"""
|
|
Get user descriptions stored in Active Directory.
|
|
|
|
Module by Tobias Neitzel (@qtc_de)
|
|
"""
|
|
|
|
name = "user-desc"
|
|
description = "Get user descriptions stored in Active Directory"
|
|
supported_protocols = ["ldap"]
|
|
opsec_safe = True
|
|
multiple_hosts = True
|
|
|
|
def __init__(self, context=None, multiple_options=None):
|
|
self.keywords = None
|
|
self.search_filter = None
|
|
self.account_names = None
|
|
self.context = None
|
|
self.desc_count = None
|
|
self.log_file = None
|
|
|
|
def options(self, context, module_options):
|
|
"""
|
|
LDAP_FILTER Custom LDAP search filter (fully replaces the default search)
|
|
DESC_FILTER An additional seach filter for descriptions (supports wildcard *)
|
|
DESC_INVERT An additional seach filter for descriptions (shows non matching)
|
|
USER_FILTER An additional seach filter for usernames (supports wildcard *)
|
|
USER_INVERT An additional seach filter for usernames (shows non matching)
|
|
KEYWORDS Use a custom set of keywords (comma separated)
|
|
ADD_KEYWORDS Add additional keywords to the default set (comma separated)
|
|
"""
|
|
self.log_file = None
|
|
self.desc_count = 0
|
|
self.context = context
|
|
self.account_names = set()
|
|
self.keywords = {"pass", "creds", "creden", "key", "secret", "default"}
|
|
|
|
if "LDAP_FILTER" in module_options:
|
|
self.search_filter = module_options["LDAP_FILTER"]
|
|
else:
|
|
self.search_filter = "(&(objectclass=user)"
|
|
|
|
if "DESC_FILTER" in module_options:
|
|
self.search_filter += f"(description={module_options['DESC_FILTER']})"
|
|
|
|
if "DESC_INVERT" in module_options:
|
|
self.search_filter += f"(!(description={module_options['DESC_INVERT']}))"
|
|
|
|
if "USER_FILTER" in module_options:
|
|
self.search_filter += f"(sAMAccountName={module_options['USER_FILTER']})"
|
|
|
|
if "USER_INVERT" in module_options:
|
|
self.search_filter += f"(!(sAMAccountName={module_options['USER_INVERT']}))"
|
|
|
|
self.search_filter += ")"
|
|
|
|
if "KEYWORDS" in module_options:
|
|
self.keywords = set(module_options["KEYWORDS"].split(","))
|
|
elif "ADD_KEYWORDS" in module_options:
|
|
add_keywords = set(module_options["ADD_KEYWORDS"].split(","))
|
|
self.keywords = self.keywords.union(add_keywords)
|
|
|
|
def on_login(self, context, connection):
|
|
"""
|
|
On successful LDAP login we perform a search for all user objects that have a description.
|
|
Users can specify additional LDAP filters that are applied to the query.
|
|
"""
|
|
self.create_log_file(connection.conn.getRemoteHost(), datetime.now().strftime("%Y%m%d_%H%M%S"))
|
|
context.log.info(f"Starting LDAP search with search filter '{self.search_filter}'")
|
|
|
|
try:
|
|
sc = ldap.SimplePagedResultsControl()
|
|
connection.ldapConnection.search(
|
|
searchFilter=self.search_filter,
|
|
attributes=["sAMAccountName", "description"],
|
|
sizeLimit=0,
|
|
searchControls=[sc],
|
|
perRecordCallback=self.process_record,
|
|
)
|
|
except LDAPSearchError as e:
|
|
context.log.fail(f"Obtained unexpected exception: {str(e)}")
|
|
finally:
|
|
self.delete_log_file()
|
|
|
|
def create_log_file(self, host, time):
|
|
"""
|
|
Create a log file for dumping user descriptions.
|
|
"""
|
|
logfile = f"UserDesc-{host}-{time}.log"
|
|
logfile = Path.home().joinpath(".cme").joinpath("logs").joinpath(logfile)
|
|
|
|
self.context.log.info(f"Creating log file '{logfile}'")
|
|
self.log_file = open(logfile, "w")
|
|
self.append_to_log("User:", "Description:")
|
|
|
|
def delete_log_file(self):
|
|
"""
|
|
Closes the log file.
|
|
"""
|
|
try:
|
|
self.log_file.close()
|
|
info = f"Saved {self.desc_count} user descriptions to {self.log_file.name}"
|
|
self.context.log.highlight(info)
|
|
except AttributeError:
|
|
pass
|
|
|
|
def append_to_log(self, user, description):
|
|
"""
|
|
Append a new entry to the log file. Helper function that is only used to have an
|
|
unified padding on the user field.
|
|
"""
|
|
print(user.ljust(25), description, file=self.log_file)
|
|
|
|
def process_record(self, item):
|
|
"""
|
|
Function that is called to process the items obtained by the LDAP search. All items are
|
|
written to the log file per default. Items that contain one of the keywords configured
|
|
within this module are also printed to stdout.
|
|
|
|
On large Active Directories there seems to be a problem with duplicate user entries. For
|
|
some reason the process_record function is called multiple times with the same user entry.
|
|
Not sure whether this is a fault by this module or by impacket. As a workaround, this
|
|
function adds each new account name to a set and skips accounts that have already been added.
|
|
"""
|
|
if not isinstance(item, ldapasn1.SearchResultEntry):
|
|
return
|
|
|
|
sAMAccountName = ""
|
|
description = ""
|
|
|
|
try:
|
|
for attribute in item["attributes"]:
|
|
if str(attribute["type"]) == "sAMAccountName":
|
|
sAMAccountName = attribute["vals"][0].asOctets().decode("utf-8")
|
|
elif str(attribute["type"]) == "description":
|
|
description = attribute["vals"][0].asOctets().decode("utf-8")
|
|
except Exception as e:
|
|
entry = sAMAccountName or "item"
|
|
self.context.error(f"Skipping {entry}, cannot process LDAP entry due to error: '{str(e)}'")
|
|
|
|
if description and sAMAccountName not in self.account_names:
|
|
self.desc_count += 1
|
|
self.append_to_log(sAMAccountName, description)
|
|
|
|
if self.highlight(description):
|
|
self.context.log.highlight(f"User: {sAMAccountName} - Description: {description}")
|
|
|
|
self.account_names.add(sAMAccountName)
|
|
|
|
def highlight(self, description):
|
|
"""
|
|
Check for interesting entries. Just checks whether certain keywords are contained within the
|
|
user description. Keywords are configured at the top of this class within the options function.
|
|
|
|
It is tempting to implement more logic here (e.g. catch all strings that are longer than seven
|
|
characters and contain 3 different character classes). Such functionality is nice when playing
|
|
CTF in small AD environments. When facing a real AD, such functionality gets annoying, because
|
|
it generates too much output with 99% of it being false positives.
|
|
|
|
The recommended way when targeting user descriptions is to use the keyword filter to catch low-hanging fruit.
|
|
More dedicated searches for sensitive information should be done using the logfile.
|
|
This allows you to refine your search query at any time without having to pull data from AD again.
|
|
"""
|
|
for keyword in self.keywords:
|
|
if keyword.lower() in description.lower():
|
|
return True
|
|
return False
|