In this lesson,
we will discuss network sniffing, an important part
of network reconnaissance that helps penetration testers
and security professionals uncover vulnerabilities
and monitor network traffic in real time.
Network sniffing involves capturing packets of data
as they travel across a network.
In this lesson, we will cover the process of using PCAP,
or Packet Capture files, analyzing them with Wireshark,
and understanding the complexities
of handling Internet of Things
and Operation Technology protocols,
which often require specialized tools
beyond the standard suite.
Network reconnaissance focuses on gathering information
about a network's topology and architecture,
identifying active hosts, services,
and key communication endpoints.
This phase lays the groundwork
for further penetration testing activities
to provide a roadmap of the network landscape.
Now, effective reconnaissance can expose weaknesses
in the network configurations, and of course,
outdated protocols that could be exploited.
PCAP files are instrumental in network sniffing
and cybersecurity diagnosis at large.
These files capture and log the data
flowing across the network during a specified period
of time, making them useful for detailed analysis.
Now, by recording all of these network transactions,
PCAP files allow security testers
to replay network interactions
to identify and analyze specific events.
This can be useful
for diagnosing intermittent network issues
or for forensic analysis after a security breach.
For example, using tools like tcpdump,
tester can capture all packets transmitted
over the network interface.
Now, just suppose a company suspects data leakage
via a unknown service.
Now, the tester could capture the traffic
to and from the suspected machine and analyze the PCAP file
with Wireshark to trace data packets' origins
and their destination.
This might reveal unauthorized external connections
or data being sent to a suspicious IP address.
One of the most popular tools
for using PCAP files is Wireshark.
Wireshark is known for its ability
to analyze network traffic.
It presents a well-designed and nice user-friendly interface
where data packets can be examined in depth.
One of Wireshark's most powerful features
is its filtering capabilities, which allows users
to isolate packets based on numerous criteria,
such as protocols, IP addresses, port numbers, and more.
Consider a network where a network admin
needs to troubleshoot an intermittent connection issue
on a corporate network.
By loading the relevant PCAP files into Wireshark,
the admin can use filters to isolate packets
related to the services that are having problems.
For instance, if a web application intermittently fails,
filtering HTTP and HTTPS packets can help pinpoint times
when failure occurs or reveal error codes returned
by the server, guiding further investigation.
In pen testing, you might capture traffic using tcpdump
and then analyze the PCAP file using Wireshark
to trace data packets' origins and destinations,
potentially revealing unauthorized external connections
to the database.
With that being said, we could also use this information
to use that for our leverage
when we're trying to identify specific holes
in the system that we can use to form our attack.
Next, let's get into the IoT and OT domain really quick.
An emerging sector
for deploying network sniffing technologies
is in IoT and OT domains, which is Internet of Things
and operation technologies.
IoT and OT environments often employ specialized protocols
that are slightly different than those used
in the traditional IT network.
For example, MQTT
or Message Queuing Telemetry Transport,
is widely used in IoT for lightweight messaging
between devices with low bandwidth,
and Modbus is commonly used in industrial environments
to establish primary/secondary relationships
between controllers.
Now, these specialized protocols
may not be immediately interpretable
by the standard network analysis tools
and may require additional configurations
or plugins in Wireshark.
For instance, analyzing traffic
from industrial control systems using Modbus
might require a Modbus dissector in Wireshark,
which interprets the data packet
specific to Modbus communications.
Making sure that we analyze these protocols
in a proper manner is crucial as they can be prompt targets
for cyber attacks aimed at disrupting industrial operations
or commandeering IoT devices.
By understanding and monitoring these protocols,
testers can detect anomalies,
such as unusual command sequences
or unauthorized access attempts,
which could signify a breach
or attempt to compromise the system.
So, remember, network sniffing is an essential skill
for any security professional.
It provides deep visibility into the network operations,
which is critical for uncovering
and understanding both normal and malicious behaviors
within the network.
Now, using PCAP captures in tools like Wireshark
for detailed analysis, along with adapting
to the unique demands of IoT and OT protocols,
these are fundamental practices
for robust network security assessments
and ensuring the integrity and security
of both traditional and modern network environments.