Network forensics1

Network Forensics

1Network Forensics

Cyber Threat Evolution

Virus

Breaking Web Sites

Malicious Code

(Melissa)

Advanced Worm / Trojan (I LOVE YOU)

Identity Theft (Phishing)

1995 2000 2003-04 2005-06 2007-081977

Organised CrimeData Theft, DoS /

DDoS

Data TheftBotnet

Targeted Attacks

2009-10

Global Attack Trend

Source: Websense

Network Forensics ?

• What we have seen is DEAD analysis • Network evidences are highly volatile. • Needs real time analysis of network traffic.

4Network Forensics

Network Forensics

• Network forensics is the capture, recording, and analysis of network events in order to discover the source of security attacks or other problem incidents.

• The ultimate goal is to provide sufficient evidence to allow the criminal to be successfully prosecuted.

• Network forensics can reveal evidence that is crucial to building a case.

• Forensics for computer networks is extremely difficult and depends completely on the quality of information you maintain.

5Network Forensics

Why network-based evidence?

– Host-centric forensics is an established discipline, but many investigators ignore or do not understand network traffic

– Network-based evidence can be found everywhere

– Network-based evidence can be easy to collect -- without anyone's notice

Applications

Operating System

Network

Vulnerability

Vulnerability Exploitation Trends

*Symantec

Network Forensics ModelDetect

Identify

Preserve

Research

Extract

Solve

ProactiveForensics

ReactiveForensics

Capture

Data Aggregation

Data Validation

Data Analysis

Data Confirmation

Network ElementsPC

Laptop

Web Server

Web Server

Mail Server

DB Server

Firewall

IDS / IPS

Switch

Router

Wifi Router

Access Point

MX

Proxy

Relay

Network Forensics

• Systematic Capture and Analysis of network events and traffic in order to trace and prove a network incident.

– Online Capture and Analysis– Offline Analysis

Network-based evidence complements host-basedevidence.

Network traffic can be used to show a timed sequence of user’s network activities.

Suspicious network activities can be monitored real-time.

Online Analysis of Network Traffic

Network traffic also enables an investigator to extract information that is difficult to obtain from host-based evidence, such as

IP addresses and other identity information a user usesPasswords

•Specialized knowledge and tools are required to process network traffic as a source of evidence.

In general, there is only one chance to capture real-timenetwork data from a network.


Online Monitoring

If you need to have online analysis of network you need to capture packets.

Network Traffic Analysis requires online capturing and analysis of packets in real time.

Used in Stateful Analysis

IPSIDSFirewall

Capturing

Network Traffic Flow Analysis

Capturing Network Traffic using

TAPSInLine DevicesHubsSPAN Ports

TAPS

Test Access Ports

Devices specially built for accessing traffic between network devices

Usually pre-installed at important traffic points

Physical devices are able to capture traffic at the physical layer

TAPS

Similar to a tap, but implemented using a computer having at least two bridged NICs

The two devices being monitored are connected to these two NICs

Traffic through the bridged NICs is available to the computer or another device connected to an extra NIC

Inline devices are also used to enforce access control.

Inline device

The simplest and cheapest way to gain access to network traffic

A hub forwards frames to all ports.

A monitoring station, connected to one of the ports, sees all traffic passing through the hub.

Hub

SPAN Port - Switched Port Analyzer(Port Mirroring)

Provided on good switches

A switch can be configured to copy one or more switch ports to a dedicated port.

A capture device connected to the SPAN port sees traffic flowing through specified switch ports.

A SPAN port only copies valid network packets.Error packets may be ignored and not copied.

Collecting Network Traffic as Evidence

• Position the sensor properly• Consider perimeter monitoring

scenario at right– Perimeter is easiest place to

monitor– However, sensor as shown

may not be able to see all the traffic an analyst needs to understand the scope of an intrusion

• Alternative deployments shown on following slides


• At left we monitor perimeter (via tap) and DMZ (via switch SPAN)

• At right we add a filtering bridge/sensor to watch and/or control a high value target


• Don't forget to accommodate address translation issues• Here we add a second interface behind the gateway


• This network shows a variety of instrumentation options


• Verify the sensor collects traffic as expected


• Consider using Network Security Monitoring principles to guide your data collection strategies– Alert data (Snort, other IDSs)

• Traditional IDS alerts or judgments (“RPC call!”)• Context-sensitive, either by signature or anomaly

– Full content data (Tcpdump)• All packet details, including application layer• Expensive to save, but always most granular analysis

– Session data (Argus, SANCP, NetFlow)• Summaries of conversations between systems• Content-neutral, compact; encryption no problem

– Statistical data (Capinfos, Tcpdstat)• Descriptive, high-level view of aggregated events

• Sguil (www.sguil.net) is an interface to much of this in a single open source suite

Protecting and Preserving Network-Based Evidence

• Hash traces after collection and store hashes elsewhere• Understand forms of evidence• Copy evidence to read-only media when possible• Create derivative evidence• Follow chains of evidence


• Understand forms of evidence• Best evidence should, to the extent practically possible, never be analyzed

directly. – Rather, investigators should make working copies of the best

evidence, and analyze those duplications.– Network traffic saved on a sensor is the best evidence available.– Copies of that traffic transferred to a central location become working

copies.


Create derivative evidence1. Ensure you have a hash of the original file stored in a safe

location.2. After verifying the hashes match, use the desired Packet

Analysis to extract packets of interest to a new file and directory.

3. Hash the resulting file 4. Make multiple copies of the new local evidence file, and

analyze them at will.5. Document these steps on both platforms.

Analyzing Network-Based Evidence

• Validate results with more than one system• Beware of malicious traffic• Document not just what you find, but how you found it• Follow a methodology

Trends

• Significant increase in network-based DoS attacks over the last year– Attackers’ growing accessibility to networks– Growing number of organizations connected to

networks• Vulnerability

– Most networks have not implemented spoof prevention filters

– Very little protection currently implemented against attacks

Goals of Attacks

• Prevent another user from using network connection– “Smurf” attacks, “pepsi” (UDP floods), ping floods

• Disable a host or service– “Land”, “Teardrop”, “Bonk”, “Boink”, SYN

flooding, “Ping of death”• Traffic monitoring

– Sniffing

“Smurfing”

• Very dangerous attack– Network-based, fills access pipes– Uses ICMP echo/reply packets with broadcast networks to multiply

traffic– Requires the ability to send spoofed packets

• Abuses “bounce-sites” to attack victims– Traffic multiplied by a factor of 50 to 200– Low-bandwidth source can kill high-bandwidth connections

• Similar to ping flooding, UDP flooding but more dangerous due to traffic multiplication

“Smurfing” (cont’d)

Internet

Perpetrator

Victim

ICMP echo (spoofed source address of victim)Sent to IP broadcast address

ICMP echo reply

“Smurfing” trend

• Smurf attacks are still “in style” for attackers• Significant advances made in reducing the

effects– Education campaigns through the use of white

paper and other education by NOCs has reduced the average “smurf” attack from 80 Mbits/sec to 5 Mbits/sec

• Most attacks can still inundate a T1 link

“Teardrop”, “Bonk”, “Boink”, “Ping of Death”

• Goal is to severely impair or disable a host or its IP stack

• Use packet fragmentation and reassembly vulnerabilities

• Require that a host IP stack be able to receive a packet from an attacker

SYN flooding

• Goal is to deny access to a TCP service running on a host

• Creates a number of half-open TCP connections which fill up a host’s listen queue; host stops accepting connections

• Requires the TCP service be open to connections from the victim

Sniffing

• Goal is generally to obtain information– Account usernames, passwords– Source code, business critical information

• Usually a program placing an Ethernet adapter into promiscuous mode and saving information for retrieval later

• Hosts running the sniffer program is compromised using host attack methods.

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Network Packet Analysis

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Packet Switched Networks

• Each message is divided into small data blocks called packets

• Packets are stored, and forwarded by intermediate nodes

• Packets from different nodes, and process get intermixed in the network

• Packets may follow different routes

• Shortest path to the destination

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Sender

Process

Router

Receiver

…

……

Packet Route

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Sender

Process

Router

Receiver

…

……

Packet Route

43

Benefits

• No user can monopolise the link for long time

• Network traffic load balancing

• Doesn’t waste resources of network

• No congestion at connection setup time

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Drawbacks

• Packets may arrive out of order. Message needs to be re-assembled at receiving end.

• May cause delay in real-time applications (audio/video)

• Service is not guaranteed

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– Is a formatted block of data carried by a computer network

– Internet, LAN uses packet technology to transfer data

– Key components are header and data

Packet

DataHeader

Packet

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Data

• Information to be conveyed between sender and the receiver

• It can be text or binary– Images, documents, web page, email …

• It may be small enough to store in a single packet or else it has to be split and stored in multiple packets

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Header

• Meta information added to the data

• With the help of header data reach the destination correctly

• Header contains Address, Length, Type, Error detection code, Packet order, Status flag …

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Why header is needed?

• To ensure delivery to the right receiver• To ensure correctness and order of data• Proper routing of packets

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Packetisation

TCP/IP Protocol

Stack

Message

Packets

Sender

NIC

Process

TCP/IP Protocol

Stack

Message

Packets

Receiver

Process

Communication Link

Network Interface Card

1 2 1 2

NIC

Eg. Internet Explorer

Eg. Web server

MesH1 sageH2 MesH1 sageH2

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Protocol Suite• Collection of protocols to deliver data• Eg. TCP/IP, Xerox XNS, DECnet, AppleTalk

Application

Transport

Internet

Link

TCP/IPApplication

Transport

Network

Data Link

Physical

ISO/OSI

Presentation

Session

Xerox XNSLevel 4+

Level 2

Level 1

Level 0

Level 3

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TCP/IP Layers - Link Layer

• Main responsibility is to move the packet between hosts through physical medium

• Network interface card and its device driver does this

• Adds the link layer specific address and other details to the packet

• Has mechanism to resolve the physical address from logical address, in broadcast networks

• Characteristics of the communication signal is handled here

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TCP/IP Layers - Network Layer• Main responsibility is to move the packet between network and

to reach the final destination (Routing)

• This is an unreliable protocol, higher layers has to add reliability

• Handles fragmentation and reassembly of packets, when passed through different networks.

• Facility for error handling and diagnosis – special protocols for conveying the intermediate node status and errors occurred

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TCP/IP Layers - Transport Layer• End to end message transfer facility or process to process

communication

• Have facility for flow control and error control

• This layer can add reliability to the data transferred

• Splits the large data in to small chunks for the network layer

• This layer associates the packet with a particular application through ports

• Port - Port is a logical address, it has nothing to do with the physical ports present on a computer.

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TCP/IP Layers - Application Layer

• Handles the details of particular application, eg. Email, web

• Adds meta information to the actual data to send (or Formats the data)

• This formatted message is encapsulated in transport layer protocol

• The respective applications can interpret this message

• The message may be plain text or binary and can be encrypted or compressed

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TCP/IP stack with sample protocols

Application

Link

Transport

Internet

HTTP SMTP POP3 FTP Telnet

TCP UDP

IP

Ethernet

DNS

ICMP

ARP RARPFDDI SLIP PPP

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The way a packet is formed (Encapsulation)

App layer

Link Layer

Trans Layer

Network Layer

HTTP

TCP

IP

Ethernet

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Packet Analysis

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Uses of Packet Analysis

• Forensics analysis• Trouble shooting and debugging• Collect sensitive information• Misuse detection• Gather Network Statistics

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Forensics analysis

• To collect evidence• To track the source of attack• To learn the attacker behavior

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Trouble shooting and debugging

• Debugging network applications• Trouble shooting network problems

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Collect sensitive information

• Passwords• Emails• Other confidential data

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Misuse detection

• Company policy violation– Accessing restricted sites– Bandwidth misuse

• Email spoofing• IP spoofing• ARP spoofing

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Gather network statistics

• To collect bandwidth utilization information• To find misbehaving nodes in the network

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• Manual inspection• Filtering • Statistics• Session reconstruction

Packet Analysis Methods

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Manual Inspection

• Text search• Binary pattern search• Packet inspection• Protocol verification

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Filtering

• Filtering based on– MAC– IP– Date, Time– Pattern

• Combinations of the above– Packets between a particular date and time– Packets from a particular IP

• Complex filter expressions

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Statistics

• Based on– Bandwidth utilization– IP– Date and time– Protocol based (Email, FTP, HTTP… )

• Eg. Top mail sender

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Statistics based analysis

1.1.1.1 1.1.1.2 1.1.1.3 1.1.1.4

Nodes

Mai

ls

10

20

50

40

30

Date

1/12/1

3/14/1

Time

M B

ytes

/Sec

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

12

56

4

7

31.1.1.1

1.1.1.2

1.1.1.3

Mail traffic of individuals on different days

Data traffic to different servers

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Session reconstruction

• TCP session reconstruction– Images, emails and other files

• UDP stream reconstruction– Streamed video, audio, VoIP and other types of

communications

Packet 1 P2 P3 Pn… File 1 F2 Fm…

Network Forensics

70Network Forensics

Computer Forensics VS Network Forensics

71Network Forensics

Legal Issues

• You may not be able to use hacker techniques against them

• Laws for gathering evidence are confusing• Logs may or may not be admissible• Perpetrator may or may not be prosecutable• It is important to know about:

– Local laws on computer-related crimes– Legal processes and how to build a criminal case

72Network Forensics

Network Traffic

Network Forensics 73



Online Monitoring

• If you need to have online analysis of network you need to capture packets.

• Network Traffic Analysis requires online capturing and analysis of packets in real time.

• Used in Stateful Analysis• IPS• IDS• Firewall





• Hash traces after collection and store hashes elsewhere• Copy evidence to read-only media when possible• Create derivative evidence• Follow chains of evidence• Understand forms of evidence• Best evidence should, to the extent practically possible, never be

analyzed directly. – Rather, investigators should make working copies of the best

evidence, and analyze those duplications.– Network traffic saved on a sensor is the best evidence available.– Copies of that traffic transferred to a central location become

working copies.




Network Forensics Procedure


Network Forensics Procedure


Analyzing Network-Based Evidence


Live Analysis

• Allows for collection of data from volatile locations such as RAM and cache.

• Often will provide extremely useful data.• Requires installation of software to capture data,

possibly erasing critical data and spoiling the “preservation” of the system.


Live Forensics - Goals


• Gathers data from running systems

• Diagnosing your system without killing it first.

• Snapshot of the state of the computer

What’s

happening n

ow?Who is doing what?

Live Forensics


Live / Volatile Data


Gathering Data

• Volatile data– registers, cache contents– memory contents– network connections– running processes

• Non-volatile data– content of filesystems and drives– content of removable media


more volatile

less volatile

Presentation And Preservation


Typical Scenario• “Dead” forensics information incomplete

– discovered to be incomplete– predicted to be incomplete

• Non-local attacker or local user using network in inappropriate fashion

• Generally, another event triggers network investigation

• Company documents apparently stolen• Denial of service attack• Suspected use of unauthorized use of file sharing

software• “Cyberstalking” or threatening email

Information Available• Summary information (router flow logs)

– Routers generally provide this information– Includes basic connection information

• source and destination IP address and ports• connection duration• number of packets sent

– No content! Can only surmise what was sent– Can establish that connections between machines were

established– Can corroborate data from log files (e.g., ssh’ing from one

machine to another to another within a network)– Unusual ports (rootkits? botnet?)– Unusual activity (spam generator?)

Information Available (2)• Complete information (packet dumps)

– from programs like Ethereal/Wireshark, snort, tcpdump– on an active net, can generate a LOT of data– can provide filter options so programs only capture certain

traffic (by IP, port, protocol)– includes full content—can reconstruct what happened

(maybe)– reconstruct sessions– reconstruct transmitted files– retrieve typed passwords– identify which resources are involved in attack– BUT no easy way to decrypt encrypted traffic

Information Available (3)

• Port scans (nmap, etc.)– Identifies machines on your network

• Often can identify operating system, printer type, etc., without needing account on the machine

• “OS fingerprinting”– Identifies ports open on those machines

• Backdoors, unauthorized servers, …– Identifies suspicious situation (infected machine,

rogue computer, etc.)– nmap: lots of options

Analysis• Does not exist in a vacuum• Link information in analysis to network and host log

files– who was on the network– who was at the keyboard– what files are on the disk and where

• Look up the other sites (who are they, where are they, what’s the connection)

• Otherwise, network traces can be overwhelming• Potentially huge amounts of data• Limited automation!

Normal ICMP Traffic (tcpdump)• Pings

IP BOUDIN.mshome.net > www.google.com: icmp 40: echo request seq 6400IP www.google.com > BOUDIN.mshome.net: icmp 40: echo reply seq 6400IP BOUDIN.mshome.net > www.google.com: icmp 40: echo request seq 6656IP www.google.com > BOUDIN.mshome.net: icmp 40: echo reply seq 6656IP BOUDIN.mshome.net > www.google.com: icmp 40: echo request seq 6912IP www.google.com > BOUDIN.mshome.net: icmp 40: echo reply seq 6912IP BOUDIN.mshome.net > www.google.com: icmp 40: echo request seq 7168IP www.google.com > BOUDIN.mshome.net: icmp 40: echo reply seq 7168

• Host unreachable

xyz.com > boudin.cs.uno.edu: icmp: host blarg.xyz.com unreachable

• Port unreachable

xyz.com > boudin.cs.uno.edu: icmp: blarg.xyz.com port 7777 unreachable

HTTP Connections• 3-way TCP handshake as laptop begins HTTP communication

with a google.com server

IP tasso.1433 > qb-in-f104.google.com.80: S 3064253594:306425359 4(0) win 16384 <mss 1460,nop,nop,sackOK>

IP qb-in-f104.google.com.80 > tasso.1433: S 2967044073:296704407 3(0) ack 3064253595 win 8190 <mss 1460>

IP tasso.1433 > qb-in-f104.google.com.80: . ack 1 win 17520

Fragmentation Visualization

• Fragmentation can be seen by tcpdump

whatever.com > me.com: icmp: echo request (frag 5000:1400@0+)

whatever.com > me.com: (frag 5000:1000@1400)

ID

size

offset

more frags flagNote that 2nd fragisn’t identifiable as ICMPecho request…

Starting Nmap 4.11 ( http://www.insecure.org/nmap ) at 2006-10-24 19:32

Interesting ports on 137.30.120.1:Not shown: 1679 closed portsPORT STATE SERVICE23/tcp open telnetMAC Address: 00:0D:ED:41:A8:40 (Cisco Systems)All 1680 scanned ports on 137.30.120.3 are closedMAC Address: 00:0F:8F:34:7E:C2 (Cisco Systems)All 1680 scanned ports on 137.30.120.4 are closedMAC Address: 00:13:C3:13:B4:41 (Cisco Systems)All 1680 scanned ports on 137.30.120.5 are closedMAC Address: 00:0F:90:84:13:41 (Cisco Systems)……

nmap 137.30.120.*

nmap 137.30.120.*Interesting ports on mailsvcs.cs.uno.edu (137.30.120.32):Not shown: 1644 closed portsPORT STATE SERVICE7/tcp open echo9/tcp open discard13/tcp open daytime19/tcp open chargen21/tcp open ftp22/tcp open ssh23/tcp open telnet25/tcp open smtp37/tcp open time79/tcp open finger80/tcp open http110/tcp open pop3111/tcp open rpcbind143/tcp open imap443/tcp open https512/tcp open exec……

Wireshark (aka Ethereal)

Detailed packet data at various protocol levels

Packet listing

Raw data

Wireshark: Following a TCP Stream

Wireshark: FTP Control Stream

Wireshark: FTP Data Stream

Wireshark: FTP Data Stream

Wireshark: Extracted FTP Data Stream

Wireshark: HTTP Session

save, then trim awayHTTP headers to retrieve image

Use: e.g., WinHex

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HTTP (An application layer protocol)

Request from client

Response from server

HTML web page

Prevention Techniques

• How to prevent your network from being the source of the attack:– Apply filters to each customer network

• Allow only those packets with source addresses within the customer’s assigned netblocks to enter your network

– Apply filters to your upstreams• Allow only those packets with source addresses within your netblocks to

exit your network, to protect others• Deny those packets with source addresses within your netblocks from

coming into your network, to protect your network

• This removes the possibility of your network being used as an attack source for many attacks which rely on anonymity

Prevention Techniques

• How to prevent being a “bounce site” in a “Smurf” attack:– Turn off directed broadcasts to networks:

• Cisco: Interface command “no ip directed-broadcast”• Proteon: IP protocol configuration “disable directed-broadcast”• Bay Networks: Set a false static ARP address for bcast address

– Use access control lists (if necessary) to prevent ICMP echo requests from entering your network

– Encourage vendors to turn off replies for ICMP echos to broadcast addresses

• Host Requirements RFC-1122 Section 3.2.2.6 states “An ICMP Echo Request destined to an IP broadcast or IP multicast address MAY be silently discarded.”

• Patches are available for free UNIX-ish operating systems.

Conclusion: Network Analysis

• Potentially a source of valuable evidence beyond that available from “dead” analysis

• By the time an incident occurs, may have lost the change to capture much of the interesting traffic

• Challenging: huge volumes of data• Again, only one part of a complete investigative

strategy• This introduction didn’t include stepping stone

analysis, many other factors (limited time)

THANK YOU


NeSA – Network Session Analyser

Packet Capture

Dump

Packet Analyser

Packet Filter

Packet Rebuild

Packet Classifier

ProtocolDissectors

SessionParser

Packet Hex View

Packet Tree View

Pcap Format dump

NeSA Architecture

Hex View

Picture View

FileView

Mail View

(HTTP, SMTP, POP3 and FTP)

Filter Rules

Rebuild Rules

Parse Rules

MediaPlayer

Crypto

Packet Capture

• Uses pcap library• Captures packet in promiscuous mode• Similar capture features as of Wireshark• Stores the captured packets to the user

specified dump file• Capture filter can be supplied

– e.g. Capture only tcp traffic

Packet Filter• Based on the filter rule supplied, filters

packets as well as the TCP sessions.• Packet filter language is same as that of pcap• TCP session filter language is custom written

– Filtering based on date/time– Protcol based filter– MAC, IP and Port based filtering– Complex combinations of the above

Protocol Dissector

• Shows each field of packet in very detail• Dissects very common protocols like IP,

TCP,UDP, ARP …• Useful to get a very detailed view of each

packet• Helpful in detecting malformed packets

Packet Classifier

• At load time itself, classifies the packets to different groups in order to improve the performance of later analysis process

• TCP session filter (Rebuild filter) chooses only from this classified group of packets, thus it has to process only a very small portion of the entire dump file

Packet Analyser

• Has a packet filtering scheme• Packets can be exported• Has an easily extendible packet (protocol)

dissector• Shows the dissected packets in a hex view as

well as in a tree control as that of in Wireshark

Packet Rebuild

• Rebuilds the TCP session• Shows the rebuilt session in a hex view with

data direction indication• To identify different types of session,

colouring schemes can be given• Rebuilt session are passed to the session

parser

Session Parser• Parses the rebuilt session and tries to extract the

available files in it.• Presently parses HTTP, SMTP, POP3 and FTP.• The above are the most common application layer

protocols• More parsers can be added• Parses MIME and extracts files from it• Shows the extracted files in a thumbnail view, file view

and mail view.• These files can be exported

Distinctive Features of NeSA

• NeSA is data centric as well as packet centric, but most other tools are packet centric, This makes NeSA a distinct product– Session parser– Session filter– Session views

120

NeSA (Network Session Analyser)

• A solution developed by CDAC for offline packet analysis

• Features– TCP session reconstruction and file recovery– Packet filter– Powerful session filter– Regular expression based search– File export, especially mail export– Packet dissect view

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Packet Capture

Dump

Packet Analyser

Packet Filter

Packet Rebuild

Packet Classifier

ProtocolDissectors

SessionParser

Packet Hex View

Packet Tree View

Pcap Format dump

NeSA Architecture

Hex View

Picture View

FileView

Mail View

(HTTP, SMTP, POP3 and FTP)

Filter Rules

Rebuild Rules

Parse Rules

MediaPlayer

Crypto

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Future plan –Moving to online

• Real-time packet analysis• Decryption support• Support for more protocols

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Catching Packets• Enable promiscuous mode of Ethernet card, from which packets

has to be caught • Otherwise OS will see only the packets which are destined to that

system only• Packet capture tools:

– tcpdump– wireshark

• Sample tcpdump comand:– tcpdump –s0 –ieth0 –wfile/to/store.dump– -s0 options tells to capture full length packet– -ieth0 options instructs to capture from the interface eth0– -w option indicates to which file the captured packets has to be stored

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Catching packets in an Enterprise

Switch

N2N1

N6N5Switch

Switch Switch

N4N3

Gateway

Only traffic of N4

Only traffic between N5,N6 and Gateway, no other traffic like “between N1 and N2”

Only packets passing through gateway, no local traffic like “between N1 and N2”

Place capture system accordingly

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126

127

128

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Issues and Challenges• Processing the large data• Lack of forensics tools• Lack of proven methods• Varied attacks• Encrypted data• Partial data• Spoofed packets• Unknown protocols

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Thank you

131

Appendix A – ICMP Message typesType Name---- ------------------------ 0 Echo Reply 1 Unassigned 2 Unassigned 3 Destination Unreachable 4 Source Quench 5 Redirect 6 Alternate Host Address 7 Unassigned 8 Echo 9 Router Advertisement 10 Router Solicitation

11 Time Exceeded 12 Parameter Problem

13 Timestamp

14 Timestamp Reply 15 Information Request

16 Information Reply

Type Name---- ------------------------- 17 Address Mask Request 18 Address Mask Reply 19 Reserved (for Security) 20-29 Reserved (for Robustness

Experiment) 30 Traceroute 31 Datagram Conversion Error 32 Mobile Host Redirect 33 IPv6 Where-Are-You 34 IPv6 I-Am-Here 35 Mobile Registration Request 36 Mobile Registration Reply 37 Domain Name Request 38 Domain Name Reply 39 SKIP 40 Photuris 41-255 Reserved

Network forensics1

Education

network traffic analysis

network forensics4

network forensics5

valid network packets

suspicious network activities

andanalysis of network

provea network incident

analysis offline analysis