What is spear phishing and how does it work?

Spear phishing is a highly targeted type of phishing in which attackers craft personalised emails or messages aimed at specific individuals or organisations. The goal is often to steal sensitive data or install malware. Unlike mass phishing attempts, spear phishing uses personal details about the victim to make the communication appear especially credible.

What is spear phishing?

The principle of phishing is straightforward: cybercriminals create fake phishing emails, websites, or even text messages that appear genuine and trick users into revealing their login details. This allows attackers to access accounts for online shopping, social media, cloud storage, and other services.

Spear phishing is a more targeted variant of phishing. Instead of sending spam emails to a wide audience, attackers carefully select specific victims or groups. By using concrete information about their targets, they can craft highly convincing messages and websites. Although this method requires more effort, the success rate is significantly higher.

How does spear phishing work?

Spear phishing carefully selects its victims and tailors each fraud attempt to specific individuals. As a result, these attacks often focus on businesses and organisations. Unlike typical fraudsters who steal data to sell on the darknet, spear phishers frequently pursue targeted goals — for example, damaging a company, conducting industrial espionage, or launching cyberattacks against military targets or critical infrastructure.

Before striking, attackers typically research their victims in detail to increase their credibility. They then craft emails that appear to come from authority figures or fictitious business partners. This makes spear phishing especially effective in large, international corporations where employees may not be familiar with the entire organisational structure. Victims are tricked into revealing sensitive data or downloading malware.

An example of spear fishing

Imagine a hacker targeting an international corporation. Their first step is to gather as much information as possible: How is the company structured? How does communication flow within the organisation? Which sectors is the company active in? They also look for an email distribution list to obtain relevant addresses.

However, the attacker won’t send an email to the entire company — the risk of being detected is too high. Instead, they carefully select individuals and address them directly. Detailed employee information is often collected in advance through social networks, making the message appear especially credible. Supposedly high-ranking colleagues from another branch are listed as the sender. Since names and email addresses can be forged, it’s not immediately obvious that the message is fraudulent.

The email contains a button leading to a forged website, while the actual target is hidden. Once the victim clicks through, malware can be downloaded in the background. If it infiltrates the PC, the attacker may be able to spy on the entire corporate network.

At this stage, the victim still believes they’ve visited a legitimate website — perhaps even just completed a harmless survey. Meanwhile, the malware spreads undetected through the company’s systems, giving the hacker full access or the ability to disrupt critical business processes.

How to protect yourself from spear phishing

Tip 1: Stay skeptical

The best defense against spear phishing is a healthy dose of skepticism. Avoid clicking on unfamiliar links or opening unexpected attachments — this alone greatly reduces the risk of becoming a victim. The difficulty lies in the fact that spear phishing attacks are far more sophisticated than typical phishing attempts. While ordinary spam emails are often easy to spot due to poor grammar or unrealistic claims, spear phishing messages are carefully crafted to appear polished, credible, and authentic.

Tip 2: Keep a cool head

Spear phishing attacks exploit human weaknesses, especially curiosity and fear. People who worry about missing out on important information are more likely to lower their guard and take the bait. That’s why these messages often promise content that seems beneficial for one’s career or appear so authoritative that ignoring them feels risky or even dangerous.

Tip 3: Protect sensitive data

Spear phishing can only work if the attacker finds enough information about the victim. Social media accounts are the first place to look. Therefore, you should not reveal too much about yourself on these platforms, especially not work-related information. Through social engineering, scammers attempt to gather additional information. It’s crucial to remain cautious: never give sensitive data to strangers, no matter how trustworthy they seem.

Tip 4: Check senders in the sending protocol

You can often spot the illegitimacy of a message by examining it more closely. In emails, pay particular attention to the sender’s address. While the display name and alleged address can be forged, the actual sending address is found in the email’s protocol.

Many modern email clients, such as Outlook, hide this information in favour of a simple display name. However, you can usually view the email header, which reveals the true source. If the details there don’t match the supposed sender, the message is likely fraudulent.

Tip 5: Avoid HTML and image downloads

Another safety measure in email communication is to avoid using HTML and to not allow images to automatically download. This prevents malicious programs from finding their way onto the victim’s computer just by opening the message.

Tip 6: Do not open unknown attachments

Attachments from unknown senders should never be opened. Always verify the sender’s identity first. Even if the email looks legitimate, avoid opening files from people you haven’t communicated with before. Be cautious even with familiar contacts: their computer may already be infected with malware, and the attachment could be part of the spread. If in doubt, confirm with the sender directly before opening any files.

Tip 7: Carefully check URLs and links

Be cautious with the web addresses behind links. You can usually preview them before clicking on the hyperlink. Attackers often use URL-spoofing to make a domain look legitimate. With a little attention, this trick can often be uncovered. Shortened links that obscure the actual address should either be expanded to their original form or avoided entirely.

Tip 8: Make email senders spoof-proof

Beyond individual protective measures, the technical configuration of your mail server is crucial in defending against spear phishing. With SPF records, DKIM, and especially DMARC, sender addresses can be secured so that emails supposedly originating from a domain can be technically verified. This helps companies prevent cybercriminals from sending fraudulent messages in their name.