Email remains hackers’ first choice for launching attacks on unsuspecting companies because it’s easy, inexpensive, and effective. Phishing messages take advantage of the weakest link in any security strategy—humans—and for every tool security experts develop to close that gap, cybercriminals find a way around it.
Hidden text salting is the latest approach to thwarting email security, and it’s deceptively simple.
The Email Security Threat That Hides in Plain Sight
Security researchers at Cisco Talos recently released a guide detailing how criminals are “seasoning” emails with irrelevant language and hidden elements in the HTML or CSS code. This hidden text salting makes email security bypass easier because it confuses the spam filters, email parsers, and other tools that detect the signs of phishing messages.
The result? Even powerful email filters become confused and allow potentially harmful messages to pass through and land in your employees’ inboxes. For example, the hackers embedded French words in one attack in an email. The spam filter didn’t recognize them, and instead of directly sending the messages to the junk mail folder, it delivered them to the inbox.
Other attacks exploit features in the coding languages that control the appearance of the email. Hackers can include a “visibility:hidden” command in the email code to disguise traits that would normally trigger email security controls.
Whatever approach the hackers take, these email scam techniques are effective and can have significant consequences for your business.
How You Can Counter Hidden Text Evasion Techniques and Protect Your Company
Even when you follow expert recommendations for email security, including in-depth employee education, training, and testing, hidden text salting represents a significant challenge to your security stance. Your employees can’t react to what they can’t see, and when an email is otherwise convincing, it’s easy to see why they can slip through.
That’s why your IT security team needs to implement new tools and policies to address salting in phishing attacks. Experts recommend several tactics to accomplish this.
Read Emails in Plain Text Mode
Emails delivered in plain text mode might not be as visually appealing as those with HTML formatting, but removing those features eliminates a hacker’s ability to hide malicious code. Plain text doesn’t accommodate links or images, so there’s less risk that those elements can hide harmful content.
Use Advanced Email Filtering Techniques
Instead of setting your email filters solely on keywords, addressing hidden text salting requires upgrading the filters to detect abuse of HTML and CSS properties. Scanning the structure and design of the email, in addition to its content, can catch some poisoned messages before they land in inboxes.
Implement AI Tools
Protecting your company from phishing attempts as criminals become more sophisticated requires using more sophisticated tools. AI-powered email security solutions use machine-learning models to evaluate messages, identify threats, and thwart messages that contain hidden text salting and elements designed to evade detection. With powerful AI and visual feature-based detection techniques, your company is less likely to become a victim of a phishing attack.
