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third.py
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third.py
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#!/usr/bin/env python
from scapy.all import sniff
import scapy.all as scapy
import sys
import oyaml as yaml
from collections import OrderedDict
import StringIO
from io import BytesIO as StringIO
import os
import re
import datetime, time
import nids
# from datetime import timezone, datetime
uniqipids = {}
ippackets = list()
fragmentedpackets = list()
fragmenttrain = list()
if (len(sys.argv) == 1):
print "Please provide configuration yaml file as an argument."
sys.exit()
with open(sys.argv[1], 'r') as stream:
try:
d = yaml.load(stream)
except yaml.YAMLError as exc:
print(exc)
# Breaking down Dictionary for Values.
# pcap_path = '/root/Desktop/ip_frag1.pcap'
# pcap_path = '/root/Desktop/tcp1.pcap'
# pcap_path = '/root/Desktop/facebook_random2.pcap'
pcap_path = d['pcap_path']
interface = d['interface']
network = d['network']
enable_checksums = d['enable_checksums']
ipv4_default_behavior = d['ipv4_fragment_reassembly']['default_behavior']
ipv4_endpoint_behavior = d['ipv4_fragment_reassembly']['endpoints'][0]['behavior']
ipv4_address = d['ipv4_fragment_reassembly']['endpoints'][0]['ipv4_address']
tcp_default_behavior = d['tcp_reassembly']['default_behavior']
tcp_endpoint_behavior = d['tcp_reassembly']['endpoints'][0]['behavior']
tcp_ipv4_address = d['tcp_reassembly']['endpoints'][0]['ipv4_address']
name = d['rules'][0]['name']
destination_port = d['rules'][0]['destination_port']
content = d['rules'][0]['content']
#content = "facebook"
frag_size = 8
# IDEA:
'''
First check if packets through Interface or through a pcap.
Find the network.
Then compute ipv4 and tcp checksums, if enabled.
For every packet, Do iPv4 fragment reassembly, based on default or current behavior.
Then for every packet, Do TCP reassembly, based on default or current behavior.
Then for those packets after TCP reassembly, check the destination port first and look for the content (regex) in the defragmented TCP and save it.
'''
##########################################################################################
# CHECKSUM
def iptcpchecksum():
for packet in pcap_file:
if packet.haslayer(scapy.IP) and not packet.haslayer(scapy.TCP):
# packet.show()
# packet.ttl = packet.ttl - 1
# del packet.chksum
del packet[scapy.IP].chksum
# del packet[scapy.TCP].chksum
x = packet.show2(dump=True)
# print(packet[scapy.IP].chksum)
# print(x)
# print(type(x))
# Get the four values of "0x" in output of show2(), 3rd IP, 4th TCP
chksum_list = []
for word in x.split():
if "0x" in word:
chksum_list.append(word)
ip_chksum = chksum_list[2]
# tcp_chksum = chksum_list[3]
# print("IP checksum ", ip_chksum)
# print("TCP checksum ", tcp_chksum)
# if 'chksum' in x:
# print("Yes")
elif packet.haslayer(scapy.IP) and packet.haslayer(scapy.TCP) and not packet.haslayer(scapy.ICMP):
# packet.show()
# packet.ttl = packet.ttl - 1
# del packet.chksum
del packet[scapy.IP].chksum
del packet[scapy.TCP].chksum
x = packet.show2(dump=True)
# print(packet[scapy.IP].chksum)
# print(x)
# print(type(x))
# Get the four values of "0x" in output of show2(), 3rd IP, 4th TCP
chksum_list = []
for word in x.split():
if "0x" in word:
chksum_list.append(word)
ip_chksum = chksum_list[2]
tcp_chksum = chksum_list[3]
# print("IP checksum ", ip_chksum)
# print("TCP checksum ", tcp_chksum)
##############################################################################################################
# IP FRAGMENT REASSEMBLY
def networkmonitor(network):
ip, cidr = network.split('/')
def first(fragmentsin):
buffer = StringIO()
for pkt in fragmentsin[::-1]:
buffer.seek(pkt[scapy.IP].frag * frag_size)
buffer.write(pkt[scapy.Raw].load)
return buffer.getvalue()
def last(fragmentsin):
buffer = StringIO()
for pkt in fragmentsin[::1]:
buffer.seek(pkt[scapy.IP].frag * frag_size)
buffer.write(pkt[scapy.Raw].load)
return buffer.getvalue()
def linux(fragmentsin):
buffer = StringIO()
for pkt in sorted(fragmentsin, key=lambda x: x[scapy.IP].frag, reverse=True):
buffer.seek(pkt[scapy.IP].frag * frag_size)
buffer.write(pkt[scapy.Raw].load)
return buffer.getvalue()
def processfrags(fragmenttrain):
if ipv4_default_behavior != "":
if ipv4_endpoint_behavior == "":
if ipv4_default_behavior == 'last':
print
last(fragmenttrain)
elif ipv4_default_behavior == 'first':
print
first(fragmenttrain)
elif ipv4_default_behavior == 'linux':
print
linux(fragmenttrain)
elif ipv4_endpoint_behavior != "":
if ipv4_endpoint_behavior == 'last':
print
last(fragmenttrain)
elif ipv4_endpoint_behavior == 'first':
print
first(fragmenttrain)
elif ipv4_endpoint_behavior == 'linux':
print
linux(fragmenttrain)
def getTime(pkt):
pktTime = int(pkt.time)
# print "Packet Time: ", pktTime
##########################################################################################
def collect_fragment():
if enable_checksums == True:
iptcpchecksum()
for a in pcap_file:
if a.haslayer(scapy.IP):
ippackets.append(a)
for frag_pkt in ippackets:
if frag_pkt[scapy.IP].flags == 1 or frag_pkt[scapy.IP].frag > 0:
fragmentedpackets.append(frag_pkt)
for a in fragmentedpackets:
uniqipids[a[scapy.IP].id] = ''
for ipid in uniqipids.keys():
print
""
for x in fragmentedpackets:
if x[scapy.IP].id == ipid:
fragmenttrain.append(x)
# getTime(x)
processfrags(fragmenttrain)
##########################################################################################
def sniff_fragment(a):
if a.haslayer(scapy.IP):
ippackets.append(a)
for frag_pkt in ippackets:
if frag_pkt[scapy.IP].flags == 1 or frag_pkt[scapy.IP].frag > 0:
fragmentedpackets.append(frag_pkt)
for a in fragmentedpackets:
uniqipids[a[scapy.IP].id] = ''
for ipid in uniqipids.keys():
print ""
for x in fragmentedpackets:
if x[scapy.IP].id == ipid:
fragmenttrain.append(x)
processfrags(fragmenttrain)
##########################################################################################
# Packet through Interface OR PCAP check.
if pcap_path is not '':
pcap_file = scapy.rdpcap(pcap_path)
collect_fragment()
else:
sniff(iface=interface, prn=sniff_fragment, store=0, count=1000)
##########################################################################################
# IP FRAGMENT REASSEMBLY
def networkmonitor(network):
ip, cidr = network.split('/')
def first(fragmentsin):
buffer = StringIO()
for pkt in fragmentsin[::-1]:
buffer.seek(pkt[scapy.IP].frag * frag_size)
buffer.write(pkt[scapy.Raw].load)
return buffer.getvalue()
def last(fragmentsin):
buffer = StringIO()
for pkt in fragmentsin[::1]:
buffer.seek(pkt[scapy.IP].frag * frag_size)
buffer.write(pkt[scapy.Raw].load)
return buffer.getvalue()
def linux(fragmentsin):
buffer = StringIO()
for pkt in sorted(fragmentsin, key=lambda x: x[scapy.IP].frag, reverse=True):
buffer.seek(pkt[scapy.IP].frag * frag_size)
buffer.write(pkt[scapy.Raw].load)
return buffer.getvalue()
def processfrags(fragmenttrain):
if ipv4_default_behavior != "":
if ipv4_endpoint_behavior == "":
if ipv4_default_behavior == 'last':
print
last(fragmenttrain)
elif ipv4_default_behavior == 'first':
print
first(fragmenttrain)
elif ipv4_default_behavior == 'linux':
print
linux(fragmenttrain)
elif ipv4_endpoint_behavior != "":
if ipv4_endpoint_behavior == 'last':
print
last(fragmenttrain)
elif ipv4_endpoint_behavior == 'first':
print
first(fragmenttrain)
elif ipv4_endpoint_behavior == 'linux':
print
linux(fragmenttrain)
def getTime(pkt):
pktTime = int(pkt.time)
# print "Packet Time: ", pktTime
#################################################################################################################################
# TCP REASSEMBLY
# pcap_path = '/root/Desktop/facebook_random2.pcap'
end_states = (nids.NIDS_CLOSE, nids.NIDS_TIMEOUT, nids.NIDS_RESET)
globs = {'regexobj': re.compile(content)}
matchstats = {'start': 0, 'end': 0, 'size': 0}
def gettimestamp():
sometime = int(nids.get_pkt_ts())
return sometime
def inspect(data):
matchobj = globs['regexobj'].search(data)
if matchobj:
matchstats['start'] = matchobj.start()
matchstats['end'] = matchobj.end()
matchstats['size'] = matchobj.end() - matchobj.start()
return True
else:
return False
def tcpcallback(tcp):
((src, sport), (dst, dport)) = tcp.addr
if tcp.nids_state == nids.NIDS_JUST_EST:
tcp.client.collect = 1
tcp.server.collect = 1
elif tcp.nids_state == nids.NIDS_DATA:
tcp.discard(0)
if len(tcp.server.data[:tcp.server.count]) > 0 and dport == destination_port:
matched = inspect(tcp.server.data[:tcp.server.count])
if matched:
print "---"
data = OrderedDict([(
'timestamp', gettimestamp()),
('source', dict(
ipv4_address=src,
tcp_port=sport,
)),
('target', dict(
ipv4_address=dst,
tcp_port=dport,
)),
('rule', name)]
)
print(yaml.dump(data, default_flow_style=False))
tcp.client.collect = 0
tcp.server.collect = 0
tcp.kill
return
if len(tcp.client.data[:tcp.client.count]) > 0 and dport == destination_port:
matched = inspect(tcp.client.data[:tcp.client.count])
if matched:
print "---"
data = OrderedDict([(
'timestamp', gettimestamp()),
('source', dict(
ipv4_address=src,
tcp_port=sport,
)),
('target', dict(
ipv4_address=dst,
tcp_port=dport,
)),
('rule', name)]
)
print(yaml.dump(data, default_flow_style=False))
tcp.client.collect = 0
tcp.server.collect = 0
tcp.kill
return
##############################################################################
def main():
# Packet through Interface OR PCAP check.
if pcap_path is not '':
nids.param('filename', pcap_path)
else:
nids.param('device', interface)
nids.init()
nids.register_tcp(tcpcallback)
nids.run()
if __name__ == '__main__':
main()
'''
# References:
https://thepacketgeek.com/scapy-sniffing-with-custom-actions-part-1/
https://7h3ram.github.io/2013/libnids-pynids.html
https://www.sans.org/reading-room/whitepapers/detection/paper/33969
'''
'''
# Printing format
---
timestamp: 1548797500 # UNIX timestamp # Get it from getTime()
source:
ipv4_address: "8.8.8.8" # Source IPv4 address # Get
tcp_port: 34567 # Source TCP port
target:
ipv4_address: "1.1.1.1" # Target IPv4 address
tcp_port: 1234 # Target TCP port
rule: "example_rule"
'''