Hackers Exploit CSS to Evade Spam Filters
Cybercriminals are using Cascading Style Sheets (CSS) to evade spam filters and track email users. A recent report revealed that attackers exploit CSS features to bypass security measures. They can even monitor user actions without requiring JavaScript. This method threatens both privacy and security.
How Attackers Use CSS for Email Attacks
CSS is primarily used for designing web pages. However, hackers now manipulate its features to hide malicious content in emails. For example, they use properties like text-indent and opacity to conceal harmful text. This technique tricks security filters while keeping the content invisible to the recipient.
Additionally, attackers embed hidden elements that redirect victims to phishing sites. These tactics allow cybercriminals to steal sensitive information without raising suspicion. The use of legitimate HTML and CSS features makes detection even harder.
Tracking User Behavior with CSS
Beyond evading spam filters, CSS enables cybercriminals to track users. Attackers use the @media rule to gather details about a victim’s system. For instance, they can detect screen size, resolution, and color depth. This data helps them tailor attacks based on the recipient’s environment.
Moreover, hackers can monitor actions like email views and prints without users realizing it. This level of tracking poses a significant privacy risk. Even without JavaScript, CSS provides enough tools for attackers to fingerprint users effectively.
How to Protect Against CSS-Based Attacks
To stay safe, users should enable email privacy proxies to block tracking attempts. Additionally, organizations must implement advanced filtering mechanisms to detect hidden text salting and content concealment. Using security-aware email clients can also help mitigate risks. Finally, staying informed about evolving email threats is crucial for maintaining cybersecurity.
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