Sniffing Attacks and How to Defend Against Them

Sniffing attacks are gaining prominence among cybercriminals today to steal customer data and compromise network security. Sniffing attacks, a significant security risk, enable common network threat types such as man-in-the-middle attacks, insider threats etc.

They pose a crucial challenge to client-server computing today. Detecting and preventing common network adversaries is one of the most important steps in preventing common network attacks. Hence, the protection of your digital assets is pivotal in the digitalization era.

While the pandemic-induced lockdown ushered in the work-from-home culture, it also highlighted the rapidly evolving security risks. Working out of the office comes with greater risks as employees need to ensure they work from a secure network to protect sensitive information and client data. Furthermore, failure to do so can result in a massive loss of data and escalate the risk further.

In order to understand the context of sniffing in networking, this article explains the basics of packet sniffing attacks, their types, and how one can prevent them.

What are Sniffing Attacks?

Monitoring and intercepting data packets passing through a network with the help of specialized tools called packet sniffers is called “sniffing.” Data packets carry a wealth of information and facilitate the process of incoming and outgoing traffic. A sniffing attack involves the illegal extraction of unencrypted data by capturing network traffic through packet sniffers.

Legal and Illegal Use of Sniffing Tools

IT professionals and network administrators use packet sniffers to monitor network traffic, assemble information for security analysis, and identify and troubleshoot network issues from an information security context. These are examples of legal usage of packet sniffing to optimize network security.

However, these tools can also be misused for malicious purposes.

Today, it’s common to see black hat hackers using sniffing techniques. Cybercriminals use packet sniffers to steal data and sensitive information from email or web traffic over an unsecured network.

Sniffing tools are illegally used to steal critical information such as client data, passwords, banking data, or to commit identity theft. Hackers can further their nefarious activities by using stolen data in fraudulent transactions with the help of sniffing attack tools such as Wireshark, BetterCAP, WinDump, Ettercap etc.

Most people may fall prey to such sniffing attacks when they use an unsecured Wi-Fi network. Packet sniffing tools can serve as the launchpad for DDoS (Distributed Denial of Service) attacks or man-in-the-middle attacks, also known as spoofing. Consequently, these attacks can compromise the data integrity of your business.

Spoofing and Sniffing are different

Often people confuse spoofing with a sniffing attack. The terms sniffing and spoofing are frequently used interchangeably. However, sniffing is different from spoofing attacks. Sniffing includes the attacker’s direct involvement with the target. They intercept network traffic to listen for and read unencrypted data actively. On the other hand, spoofing attacks are man-in-the-middle attacks in which the attacker impersonates another person. They intercept data passing between the targets and the network to gain access to sensitive information.

Types of Sniffing 

Detecting packet sniffing takes experience and requires learning the basic concepts. So, it is essential to know the types of sniffing attacks to identify them. Two types of sniffing attacks are quite common – active and passive sniffing. The major difference between active and passive sniffing lies in the manner they operate. Let us understand them further.

Active sniffing

In active sniffing, attackers seize data packets by manipulating switch-based networks. Most networks today use a switch, which is a device connecting two network endpoints. They use the switches to forward data to a specified port using the port’s media access control (MAC) address. Attackers exploit this by injecting traffic into the LAN (Local Area Network) to enable sniffing. Common examples of active sniffing include MAC flooding, DNS (Domain Name Servers) spoofing, ARP (address resolution protocol) spoofing etc.

Passive sniffing

Passive sniffing takes place through hubs or wireless networks, and attackers use MAC addresses to read the destination ports of data. They do not make any direct communication with the target, unlike active sniffing. Most packet sniffers are difficult to detect because they are passive.

How to Prevent Sniffing Attacks

Sniffing is a common hacking technique among cybercriminals to steal sensitive data or commit identity theft. However, to prevent sniffing attacks, one can deploy a few preventive measures. Let’s look at a few steps to ensure the safety of your businesses’ networks and systems.

Avoid unsecured networks

We often read news of bank data theft where attackers steal a user’s credit card or banking information to make unauthorized changes or purchases. Well, that’s because they have fallen prey to sniffing attacks. It can occur if a user exposes their device to unsecured Wi-Fi networks. Additionally, attackers use such vulnerable networks to install packet sniffers to sniff and read all data transmitted over that network.

Another way an attacker can sniff network traffic is by creating fake-free public Wi-Fi. So, the next time you see a free and unsecured public W-Fi, remember to avoid it.

Encrypt your message with a VPN

An effective way to prevent sniffing attacks is to encrypt all your incoming and outgoing communication before sharing them using a virtual private network (VPN). Encryption enhances security and makes it difficult for hackers to decrypt the packet data.

Network scanning and monitoring

Network administrators should secure their networks by scanning and monitoring their networks with the help of bandwidth monitoring or device auditing. Therefore, this is one of the important strategies to optimize your network environment and identify the presence of sniffing attacks.

No network is safe from unauthorized intrusions by cybercriminals. Even with the most sophisticated techniques and measures in place, attackers can exploit and extract data from your network. Therefore, your organization needs to have a qualified team of ethical hackers and network administrators who can penetrate the systems and implement these checks periodically to identify network contingencies. Besides, if you are planning to advance your IT career to detect sniffing attacks or want to align your team with the right skill set, the Certified Ethical Hacker (C|EH) can help you achieve your goals.

Pursue a Career as a Certified Ethical Hacker

In information security, ethical hackers also use sniffing techniques to acquire information that could help them penetrate a system. Ethical hackers or IT professionals use packet sniffers to identify and troubleshoot network bugs.

Becoming a Certified Ethical Hacker (C|EH) would put you on the front lines of detecting and mitigating these sniffing attacks, thereby keeping the network safe. Moreover, you would learn all the techniques and tools hackers use to compromise systems, then use those same tools and techniques against cyberattacks to help protect your clients.