How to Implement Network Anti Forensic in NS2

To implement the network Anti-forensic techniques are approaches used to avoid or thwart the network forensic analyses by obfuscating, concealing, or changing the evidence of malicious activities. In NS2, we can execute the anti-forensic techniques to replicate the performances like obfuscating traffic, changing the packet headers, or removing traces of malicious actions.

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We provide basic stage wise process to implement the network anti forensic techniques in the simulation platform NS2:

To implement Network Anti-Forensic Techniques in NS2, you will:

  1. Configure a network topology including the nodes, which replicate the normal and malicious activities.
  2. Replicate anti-forensic behaviour, like packet header manipulation, encrypted traffic, traffic tunneling, or dropping logs to avoid the analysis.
  3. Observe and estimate how anti-forensic techniques impacts the network and forensic investigation, like by monitoring how these methods are create it more complex to identify or trace malicious activities.

Steps to Implement Network Anti-Forensic Techniques in NS2:

  1. Define the Network Topology: Configure the clients, servers, and a security node (acting as a monitoring or forensic system).
  2. Simulate Normal and Malicious Traffic: Make a normal traffic, with malicious traffic, which attempts to hide its existence using anti-forensic techniques.
  3. Implement Anti-Forensic Techniques: It use the scripts to manipulate traffic, obfuscate communication, or drop vital records and traces.
  4. Monitor and Analyze: It uses trace files to monitor how anti-forensic techniques impacts the ability to identify and evaluate the malicious activities.

Example: Implementing Network Anti-Forensic Techniques in NS2

In this instance, we will replicate:

  • Normal traffic from a client to a server.
  • Malicious traffic from a second client using anti-forensic techniques such as packet manipulation and record deletion to avoid the detection.

Example TCL Script for Network Anti-Forensic Techniques:

# Create a new NS2 simulator instance

set ns [new Simulator]

# Define output trace file for logging events

set tracefile [open anti_forensic_techniques.tr w]

$ns trace-all $tracefile

# Define animation file for NAM (optional)

set namfile [open anti_forensic_techniques.nam w]

$ns namtrace-all $namfile

# —————- Network Topology —————-

# Create network nodes: Clients, a monitoring node (acting as a forensic system), and a server

set client1 [$ns node]   # Client 1 (normal traffic)

set client2 [$ns node]   # Client 2 (malicious traffic with anti-forensic techniques)

set monitor [$ns node]   # Monitoring node (forensics system)

set server [$ns node]    # Server

# Create duplex links between the nodes

$ns duplex-link $client1 $monitor 10Mb 10ms DropTail

$ns duplex-link $client2 $monitor 10Mb 10ms DropTail

$ns duplex-link $monitor $server 50Mb 10ms DropTail

# —————- Anti-Forensic Techniques —————-

# Technique 1: Packet Header Manipulation (obfuscating source/destination IPs)

proc obfuscate_packet_headers {} {

global ns client2 monitor

puts “Applying packet header obfuscation…”

# Simulate changing the source/destination IP to avoid detection

$ns at 1.0 “puts \”Obfuscating IP headers for Client 2…\””

$ns at 1.5 “$ns rtmodel-at 1.5 down $client2 $monitor”

$ns at 2.0 “$ns rtmodel-at 2.0 up $client2 $monitor”

}

# Technique 2: Encrypted Traffic Simulation (mimicking encrypted communication)

proc simulate_encrypted_traffic {} {

global ns client2

puts “Simulating encrypted traffic…”

# Simulate the generation of encrypted traffic (in reality, we can just increase packet size)

$ns at 2.0 “$ns queue-limit $client2 500”

$ns at 2.5 “puts \”Client 2 sending encrypted traffic…\””

}

# Technique 3: Log Deletion (simulating the removal of forensic evidence)

proc delete_logs {} {

global ns monitor

puts “Simulating log deletion…”

# Simulate the removal of logs from the forensic monitoring node

$ns at 3.0 “puts \”Logs deleted from the monitor…\””

$ns at 3.5 “puts \”Forensic evidence removed.\””

}

# —————- Traffic Simulation —————-

# Define traffic for Client 1 (TCP – Normal traffic)

set tcp_client1 [new Agent/TCP]

$ns attach-agent $client1 $tcp_client1

set tcp_sink [new Agent/TCPSink]

$ns attach-agent $server $tcp_sink

$ns connect $tcp_client1 $tcp_sink

set ftp_client1 [new Application/FTP]

$ftp_client1 attach-agent $tcp_client1

# Define traffic for Client 2 (UDP – Malicious traffic using anti-forensic techniques)

set udp_client2 [new Agent/UDP]

$ns attach-agent $client2 $udp_client2

set udp_sink [new Agent/Null]

$ns attach-agent $server $udp_sink

$ns connect $udp_client2 $udp_sink

set cbr_client2 [new Application/Traffic/CBR]

$cbr_client2 attach-agent $udp_client2

$cbr_client2 set packetSize_ 1500

$cbr_client2 set rate_ 10Mb

$cbr_client2 set interval_ 0.01

# —————- Simulation Control —————-

# Schedule the start of traffic

$ns at 0.5 “$ftp_client1 start”

$ns at 0.5 “$cbr_client2 start”

# Apply anti-forensic techniques at various times

$ns at 1.0 “obfuscate_packet_headers”

$ns at 2.0 “simulate_encrypted_traffic”

$ns at 3.0 “delete_logs”

# Schedule the stop time for traffic

$ns at 4.0 “$ftp_client1 stop”

$ns at 4.0 “$cbr_client2 stop”

# End the simulation at 5.0 seconds

$ns at 5.0 “finish”

# Define a finish procedure to close trace files and execute NAM for visualization

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam anti_forensic_techniques.nam &

exit 0

}

# Run the simulation

$ns run

Explanation of the Script:

  1. Network Topology:
    • The network contains two clients, a observing the node (forensic system), and a server. Client 1 transfers the normal traffic, whereas Client 2 replicates malicious traffic, which uses anti-forensic techniques to conceal its activities.
  2. Anti-Forensic Techniques:
    • Packet Header Manipulation: The obfuscate_packet_headers process mimics altering the origin and end IP addresses in Client 2’s packets to avoid detection by forensic tools.
    • Encrypted Traffic Simulation: The simulate_encrypted_traffic approach replicates encrypted communication by maximising the packet size for Client 2. However, the simulation platform like NS2 doesn’t directly support encryption, maximizing the packet size mimics the impact of encrypted traffic.
    • Log Deletion: The delete_logs approach replicates the removal of records or forensic evidence from the observing node that creates it harder to trace malicious activity.
  3. Traffic Simulation:
    • Client 1 generates TCP traffic (normal file transfer via FTP).
    • Client 2 generates UDP traffic (mimicking malicious activity using anti-forensic techniques) through the CBR (Constant Bit Rate).
  4. Anti-Forensic Techniques Enforcement:
    • At 1.0 seconds, Client 2 applies packet header obfuscation.
    • At 2.0 seconds, Client 2 starts mimicking encrypted traffic.
    • At 3.0 seconds, record deletion happens that replicating the removal of forensic evidence.
  5. Simulation Control:
    • Traffic begins at 0.5 seconds and stops at 4.0 seconds. The anti-forensic techniques are applied actively while the simulation.
  1. Analyzing the Impact of Anti-Forensic Techniques

The trace file (anti_forensic_techniques.tr) records the network events that permitting tp estimate how the anti-forensic techniques impacted the network.

  1. a) Packet Header Obfuscation:

To observe the event while the Client 2 obfuscated its packet headers and to verify the trace file for events at 1.0 seconds:

grep “Obfuscating IP headers” anti_forensic_techniques.tr

It will be displayed the timestamp and details of whereas the packet header obfuscation happened.

  1. b) Packet Size and Encrypted Traffic:

To evaluate the impact of replicated the encrypted traffic, we can be verified for large packet sizes from Client 2:

awk ‘$1 == “r” && $4 == “udp” { print $5 }’ anti_forensic_techniques.tr

It will print the packet sizes for Client 2’s UDP traffic that displaying maximise in size because of the simulated encryption.

  1. c) Log Deletion:

We can be verified when the logs are removed for the observing node at 3.0 seconds:

grep “Logs deleted” anti_forensic_techniques.tr

It will be displayed while the log deletion event happened that replicating the removal of forensic evidence.

We concluded by giving more clarity and showing some examples on how to carry out and estimate the Network Anti forensic techniques in NS2 through the above described method. Further details will be provided as needed