Email has stood the test of time as a vital communication tool. Yet, its accessibility and widespread use have made it the ideal channel for cybercriminals seeking to disrupt and compromise businesses. Beyond deceptive phishing scams, email bombing is a particularly frustrating and damaging form of cyberattack that businesses must defend against. This tactic can disrupt productivity, increase security risks, and cause businesses to lose control over vital communications.Â
Here’s what businesses need to know about email bombing and how to defend against this threat.
What is email bombing?
Email bombing involves flooding an email inbox with a large amount of unwanted or malicious messages. It’s similar to a denial-of-service attack, but instead of overwhelming a network, it overwhelms an email account. Attackers send massive numbers of emails, which can overload email servers, drown out legitimate communications, and disrupt productivity.
Email bombing can take on various forms, each with distinct methods and intentions:
- Mass mailing: Attackers send a large volume of messages directly to the target’s email address. Each email may contain identical content or random, unrelated text. This approach creates a flood of notifications, paralyzing an inbox with sheer volume alone. Mass mailing attacks are disruptive, forcing recipients to sift through junk to find important messages.
- List linking: Using bots or automated scripts, attackers enroll the victim’s email address in thousands of lists, resulting in a continuous stream of automated welcome emails. List linking attacks can be challenging to stop, as each message originates from a legitimate sender, making it hard to identify and filter out the source.
- Zip bombing: Cybercriminals send a compressed file, which once opened, unpacks and continues to open an endless series of files. These files may contain massive amounts of data, with the intent of overwhelming the recipient’s storage and making it impossible to open or store emails.
How businesses can defend against email bombing
Email bombing can be an alarming experience, especially if your inbox is critical to business operations. Fortunately, there are several strategies businesses can use to mitigate and defend against these types of attacks:
Update email clients and servers
While most web-based email services such as Gmail and Outlook are primed to handle significant volumes of messages, not all email clients and servers are as resilient. Businesses that are using their servers to host email services must regularly update their systems to fix flaws that open them up to email bombing attacks. Similarly, businesses should also ensure that their employees’ email clients are updated to the latest version with the necessary security patches.
Limit permissions and access
Only allow access to company email addresses based on role requirements. Some employees may not need external communication capabilities, so limiting external communication reduces the risk of those email addresses being bombed. Businesses should also restrict how email addresses are shared publicly and encourage employees to avoid using business email accounts for nonwork-related subscriptions.
Filter emails
Setting up robust spam filters is one of the most effective defenses against email bombing. Spam filters can be customized to detect suspicious patterns, block mass-mailing attempts, and restrict content based on specific criteria. What’s more, advanced email filtering tools can flag or block emails containing zip files or dangerous links.
Use CAPTCHA on contact forms
Many list linking attacks occur when bots are able to register an email address across multiple platforms. Using CAPTCHA on contact forms can prevent bots from submitting the form, making it more challenging for attackers to enroll email addresses in unwanted lists.
Regularly audit subscriptions and lists
To help prevent list linking attacks, periodically audit the subscription lists for all business email addresses. There are tools available that can scan and summarize subscriptions, making it easier to unsubscribe from irrelevant or suspicious lists. Encourage employees to avoid using company email addresses for nonessential subscriptions, such as newsletters or promotions, to keep email lists clean and manageable.
Educate employees on email bombing tactics
Employee awareness can be a strong line of defense against email bombing. Teach employees how to identify email bombing tactics such as suspicious patterns of emails or overwhelming amounts of messages from unknown senders. Employees should also know of the proper channels for reporting any identified attacks so that proper action can be taken before the whole organization is flooded with emails.
Work with a security expert
Businesses that don’t have much experience dealing with email bombing may struggle to resolve the issue quickly and efficiently. In such cases, working with a cybersecurity expert can be highly beneficial. A security expert can contain the threat, identify the source of the attack, and implement preventive measures to avoid future bombardments.
With Varsity Tech as your trusted security partner, you can secure your business from various threats, including email bombing. Contact us today to shield your business from the disruptive effects of email bombing.