HTML Smuggling

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HTML Smuggling is an evasive malware delivery technique that leverages legitimate HTML5 and JavaScript features to deploy banking malware, Remote Access Trojans (RATs), and other malicious payloads to conduct a targeted attack. As the name suggests, HTML smuggling lets an attacker “smuggle” an encoded malicious script within a specially crafted HTML attachment or web page into a company bypassing it s normal defenses. When a victim user opens the HTML in their web browser, the browser decodes an innocuous script, which then reaches out to the Internet to download the true malicious script. That, in turn, produces or reconstructs a dangerous piece of malware on the victim’s device. Along the way, because all communications were encrypted by design, the malware was smuggled onto the target user’s machine. 

HTML smuggling is made possible with the HTML5 ‘download’ attribute for anchor tags. When a user clicks on the HTML link it triggers a download of the file referenced in the ‘href’ tag. For example:


What does this mean for an SMB or MSP?

There are two basic principles that can help enormously in such cases as HTML Smuggling. First, consider implementing Network Segmentation to reduce lateral movement if an attacker gets into your network. Second, implement the Principle of Least Privilege (removing administrative rights from end-users) so if hackers attempt to compromise an end-user’s machine, perhaps they fail because the privileges aren’t there to be exploited. However, if they succeed, the user’s computer won’t have access to everything, which limits the potential damage (at least initially).
Other actions that can be taken involve security awareness training, to spot these forms of attack and prevent them from the beginning in the first place. Read on for more protective measures companies can take that don’t break the bank. 

CyberHoot’s Minimum Essential Cybersecurity Recommendations

The following recommendations will help you and your business stay secure with the various threats you may face on a day-to-day basis. All of the suggestions listed below can be gained by hiring CyberHoot’s vCISO Program development services.

  1. Govern employees with policies and procedures. You need a password policy, an acceptable use policy, an information handling policy, and a written information security program (WISP) at a minimum.
  2. Train employees on how to spot and avoid phishing attacks. Adopt a Learning Management system like CyberHoot to teach employees the skills they need to be more confident, productive, and secure.
  3. Test employees with Phishing attacks to practice. CyberHoot’s Phish testing allows businesses to test employees with believable phishing attacks and put those that fail into remedial phish training.
  4. Deploy critical cybersecurity technology including two-factor authentication on all critical accounts. Enable email SPAM filtering, validate backups, and deploy DNS protection, antivirus, and anti-malware on all your endpoints.
  5. In the modern Work-from-Home era, make sure you’re managing personal devices connecting to your network by validating their security (patching, antivirus, DNS protections) or prohibiting their use entirely.
  6. If you haven’t had a risk assessment by a 3rd party in the last 2 years, you should have one now. Establishing a risk management framework in your organization is critical to addressing your most egregious risks with your finite time and money.
  7. Buy Cyber-Insurance to protect you in a catastrophic failure situation. Cyber-Insurance is no different than Car, Fire, Flood, or Life insurance. It’s there when you need it most.

Each of these recommendations, except cyber-insurance, is built into CyberHoot’s product and virtual Chief Information Security Officer services. With CyberHoot you can govern, train, assess, and test your employees. Visit and sign up for our services today. At the very least continue to learn by enrolling in our monthly Cybersecurity newsletters to stay on top of current cybersecurity updates.

CyberHoot does have some other resources available for your use. Below are links to all of our resources, feel free to check them out whenever you like: 

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