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Layered security is a network security layer is also the most accessible and the most
approach that uses several components to protect exposed to the outside world because for the Data-Link Layer Threats
The data link layer provides reliable transit
an organization’s operations with multiple levels application to function, it must be accessible over of data across a physical link. The data link layer
of security measures. The purpose of layered Port 80 (HTTP) or Port 443 (HTTPS). Other possible is concerned with physical addressing, network
security approach is to make sure to not leave exploits at the Application Layer include viruses, topology, network access, error notification,
any single point of failure in the security design. worms, phishing, key loggers, backdoors, program ordered delivery of frames, and flow control.
In many scenarios, layered security strategy logic flaws, bugs, trojan horses and Ransomware. Frame-level exploits and vulnerabilities include
mitigates the potential weakness of one layer by sniffing, spoofing, broadcast storms, and
the strength of corresponding other layers. Presentation Layer Threats insecure or absent virtual LANs (VLANs, or lack
Individual layers in a layered security The most prevalent threats at this layer are of VLANs). Network interface cards (NICs) that
approach focuses threats possessed to malformed SSL requests. Knowing that inspecting are misconfigured or malfunctioning can cause
Confidentiality, Integrity and Availability. These SSL encryption packets is resource intensive, serious problems on a network segment or the
layers work together to tighten security and attackers use SSL to tunnel HTTP attacks to entire network.
by minimizing potential threat surface area for target the server. Mitigation plans should include Port security is important to tackle Address
intruders from breaching your network, making it options like offloading the SSL and inspecting Resolution Protocol (ARP) spoofing, Media Access
much more robust than relying on a single layer the encrypted application traffic for the signs Control (MAC) flooding or cloning, Port Stealing,
security solution. of attacks traffic or violations of policy at an Dynamic Host Configuration Protocol (DHCP)
The terms “Defence in depth” and “Layered applications delivery platform and subsequently Attacks, layer 2-based broadcasting or Denial of
security” are often used interchangeably, encrypting it after the process of inspection is Service Attacks. Switches should be configured to
however there is a subtle difference with a complete. limit the ports that can respond to DHCP requests,
lot of overlap. The term “defence in depth” static ARP should be implemented and Intrusion
refers to an even more comprehensive security Session Layer Threat Detection Systems (IDS) should be installed.
strategy approach than layered security. In fact, DDoS-attackers exploit a flaw in a Telnet server
one might say that just as a firewall is only one running on the networking devices like switches, Physical Layer Threats
component of a layered security strategy, layered rendering Telnet services unavailable. Thus, it The copper & fiber-optic cables that connect
security is only one component of a defence becomes important that networking hardware everything together create the actual network
in depth strategy. Défense in depth strategies is regularly patched for such vulnerabilities, that everything else uses. Most threats at this
also include other security preparations which proper access and session restriction policies are layer involve interruption of the electrical signals
address concerns such as: monitoring, alerting, configured and firmware is kept up-to-date. that travel between network nodes including the
and emergency response, authorized personnel physical cutting of cables, natural disasters that
activity accounting, disaster recovery, criminal bring flood waters which can cause short-circuits,
activity reporting, forensic analysis etc. But Transport Layer Threats or other human vandalism. Many organizations
Transport Layer Security (TLS) is used to
nonetheless, layered security approach is one of secure all communications between their Web mitigate these failures by bringing in multiple
most important components of Défense in Depth servers and browsers regardless of whether circuits to the internet.
strategy. A superior strategy is the placement of all
sensitive data is being transmitted. TLS is a network core elements such as servers and
Areas of Cyber Security Threats cryptographic protocol that provides end-to-end storage at multiple redundant cloud data centers
Cyber security threats exist at all the OSI/ ISO communications securely over networks and is so that services are available at all the times.
model layers starting at Layer 7 – the Application widely used for internet communications and
online transactions. It is intended to prevent
Layer because that’s the place where users begin eavesdropping, tampering and message forgery. Functional Aspects
by interfacing to the network. For the purposes Common applications that employ TLS include An analogy can be drawn between Layered
of creating the most comprehensive Cyber Web browsers, instant messaging, e-mail such as approach to security and physical security at
security plan we must actually start BEFORE Outlook and voice over IP. an airport. Just like multiple checkpoints at
the Application Layer and address perhaps the an airport serve different purpose, different
biggest vulnerability in the entire network – the layers of security also prevent different type of
user himself. Users are human and are far more Network Layer Threats cyber threats. What layers of security are used
subjected to making errors than computers which Routers make decisions based on layer 3 in practice may vary from implementation to
will perform the same function the same way information, hence the most common network implementation, but most common ones are:
every time. Threats at each layer of the ISO-OSI layer threats are generally router-related,
model include: including information gathering, sniffing, Network Perimeter Defense
spoofing, and distributed denial of service (DDoS) Perimeter defense involves firewalls,
Application Layer Threats attacks in which multiple hosts are enlisted to intrusion detection and prevention systems, and
Examples of application layer attacks include bombard a target router with requests to the DMZs. Network Perimeter defence separates an
distributed denial-of-service attacks (DDoS) point where it gets overloaded and cannot accept organization’s network from External network and
attacks, HTTP floods, SQL injections, cross-site genuine requests. prevents unauthorized access to this network. Its
scripting, parameter tampering, and Slow- The most effective protection is achieved by components include:
loris attacks. To combat these and more, most consistently observing best practices for router, Firewall: Firewall is an essential part of any
organizations have an arsenal of application layer firewall and switch configurations. At the router network security; a firewall stands as the main
security protections, such as web application itself it is important to constantly assure that barrier between the organization’s internal
firewalls (WAFs), secure web gateway services, the router operating system is up to date on all secured network and external network. While
and others. According to the experts “The security patches, packet filtering is kept enabled some firewalls are basic, others can be highly
application layer is the hardest to defend”. The and any unused ports are blocked, unused complex and sophisticated like Next Generation
vulnerabilities encountered here often rely on services, and interfaces are disabled. Logging Firewalls and Unified Threat Management devices.
complex user input scenarios that are hard to should be enabled, and regular auditing of any Intrusion Detection and Prevention: This
define with an intrusion detection signature. This unusual activity should be conducted. system is designed to monitor intrusions and

26 informatics.nic.in October 2021