Email is the backbone of business communication. From sending invoices and contracts to day‑to‑day updates with colleagues, it’s a tool that nobody can operate without. But its everyday use also makes it one of the most attractive targets for cybercriminals. For many attacks, the inbox is the front door into your organisation.
The problem is, not every business recognises just how many ways that door can be forced open. While firewalls, antivirus, and cloud security all have their role to play, the inbox itself is often the quickest route in. To stay ahead of attackers, you need to understand the tricks they rely on and how they exploit trust.
Here are four of the most common tactics hackers use when attacking email, and what you need to know to reduce your risk.
Phishing: The Oldest Trick Still Works
Phishing is the most familiar form of email attack you’ll hear about, and for good reason, it still works. These attacks trick users into clicking a link, sharing information, or handing over credentials by pretending to be someone they trust.
You’ve probably seen the typical examples: emails claiming urgent action is needed on an account, requests to reset a password, or fake invoices that look like they’ve come from a supplier. Some are easy to spot, littered with spelling mistakes or strange formatting. But many are good enough to fool even a cautious eye. Attackers now copy logos, mimic real‑world email templates, and even use similar‑looking domains to appear convincing.
In practice, this can cause serious damage. Imagine a small business where a staff member receives what appears to be an urgent CEO request to transfer funds to an account. Without pausing to verify, they comply, and the company loses thousands.
Stopping phishing requires a mix of employee awareness and intelligent filtering. Knowing to pause and double‑check suspicious messages is vital, but so is having security tools that catch and quarantine emails before they land in user inboxes.
Session Hijacking: Taking Over Your Login
Not every attack involves clicking on the wrong link. Some rely on stealing your existing access to systems. This is where session hijacking comes in, attackers capture the tokens that keep you logged into applications, then use them to masquerade as you.
In simpler words, once you’ve logged in, your system gives you a kind of “pass” in the form of a session token or cookie. If a hacker can grab that, they’ve skipped the password step completely. That means they can move around in email as if they were you, with full access to contacts, files, and messages.
Think about the risk if it’s someone in finance who gets hit. An attacker controlling that inbox could send seemingly genuine payment requests to colleagues or suppliers, reroute bank transfers, or quietly forward sensitive messages to themselves, all without the real user noticing until it’s too late.
The best defences here include multi‑factor authentication, secure browsing habits, and clear monitoring of login activity. If something unusual happens, alerts should flag it quickly. That visibility, combined with layers of authentication, makes it far harder for attackers to succeed.
Malicious Attachments: The Dangerous Download
Hackers know people are used to opening files in day‑to‑day work. Attachments like PDFs, Word documents, or spreadsheets are all business‑as‑usual. But they can also be booby‑trapped.
The malicious attachment tactic disguises harmful code inside innocent‑looking files. All it takes is one click to release ransomware that locks your system, spyware that tracks what you type, or hidden software that creates a back door into your network.
The classic example is the fake invoice. An employee sees a PDF labelled “Invoice” from what looks to be a supplier. They open it, expecting a billing record, but the file silently executes malware on their machine. In many cases, businesses don’t even know they’ve been compromised until files are encrypted or strange behaviour starts spreading.
Training employees not to blindly trust attachments is useful, but prevention needs to go further. Email security filtering that inspects attachments before delivery, checking for dangerous hidden code or unexpected macros, greatly reduces the risk. Combined with strong backup and recovery processes, this prevents one email from triggering a business‑wide crisis.
Spoofing: When An Email Isn’t What It Seems
Spoofing is another tactic that thrives on trust. Here, hackers forge the “From” address in an email to make it look like it’s coming from someone the recipient knows or relies on.
That contact could be a senior colleague, a regular supplier, or even a partner organisation. On the surface, everything looks legitimate. What’s really happening is the attacker is impersonating someone familiar to sidestep suspicion and convince the target to take an action.
Real‑world spoofing attacks often involve financial fraud. An accounts payable department might receive an email they believe to be from a supplier, instructing them to make payment into a “new” account. By the time the fraud is uncovered, the money has long gone.
Technical measures like DMARC, SPF, and DKIM can help reduce the number of spoofed emails reaching inboxes, but like every attack type, these controls aren’t perfect. Employees must still know that if an email seems unusual, even from a trusted sender, it’s worth picking up the phone or checking by another method. Trust, but verify.
Why Awareness Matters More Than Ever
The reason hackers target email so relentlessly is that it relies on human interaction. Firewalls and security appliances can block thousands of threats each day, but all it takes is one busy employee clicking the wrong thing for the defences to crumble.
That’s why awareness, combined with layers of security, matters so much. Businesses should encourage healthy scepticism toward unexpected emails, ensure employees know what suspicious signs look like, and put safeguards in place that reduce the chance of mistakes leading to disaster.
For SMBs in particular, email attacks can be expensive, time‑consuming, and damaging to reputation. But by understanding the tactics hackers use, phishing, session hijacking, malicious attachments, and spoofing, you’re already one step closer to building the resilience you need.
If you want to better protect your business from email threats and ensure your inbox isn’t the easiest way in, contact us to find out more about how we can help strengthen your defences.