ZIP-Bomben: erst klein, dann gemein 1200x627

ZIP bombs: big trouble in a small package

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Imagine this: You receive an email with a seemingly harmless ZIP file attached, just a few kilobytes in size. Your system begins to unzip the file, and crashes. What follows is a system failure, wasted storage space, or, in the worst case, a gateway for further malicious code. The cause is a ZIP bomb, detonating within your IT infrastructure. In this blog post, we explain what ZIP bombs are, how they overload systems through extreme data compression and serve as a distraction for attacks, what variants exist, and how to effectively protect against them using multi-layered security mechanisms like NoSpamProxy.

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NoSpamProxy: The Right Choice for Enterprise Environments

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CEO fraud, phishing, ransomware via infected attachments: Email remains the preferred entry point for attackers. In enterprise environments, the risk is magnified: more mailboxes, more locations, more entry points. And the attacks are becoming more sophisticated. AI-generated text, spoofed sender domains, context-specific attempts at deception – what used to be recognizable by poor spelling is now almost indistinguishable from a genuine sender. Enterprise organizations with hundreds or thousands of mailboxes, complex IT landscapes, and strict compliance requirements have unique needs. This is where NoSpamProxy comes in.

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Wie Cloaking Phishing-Angriffe tarnt 800x800

How cloaking disguises phishing attacks

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Traditional email security solutions check URLs when a message is received. If the linked page appears normal, the email is allowed to reach the inbox. But what if security systems see something different than the users who later click on the link? Cloaking techniques make this possible—and thus call into question a fundamental principle of URL filtering.

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Intelligentes Greylisting mit NoSpamProxy 800x800

Intelligent greylisting with NoSpamProxy

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Every day, millions of unwanted emails are sent over the internet. Spam filters do their best to block these emails, but some unwanted messages still find their way into our inboxes. There is a frequently overlooked but effective protective measure against spam: greylisting. The principle behind greylisting is to save time. With greylisting, emails are initially rejected and only accepted after a second delivery attempt. In addition, greylisting separates legitimate mail servers from those that do not comply with the relevant RFCs.

In this article, you will learn how greylisting works, why it is still an integral part of modern spam protection today, and why the intelligent greylisting in NoSpamProxy is particularly effective.

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