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What is HTML smuggling and what do you need to know?

Threat actors use various techniques to deliver their payloads whilst avoiding detection rules and systems, one such tactic is HTML smuggling; the method of obfuscating HTML attachments through means such as encoding.

Recently, Qakbot have employed this technique and taken it further by incorporating SVG images.

With detection rules becoming more advanced, paired with the disabling of VBA macros, tactics such as HTML smuggling have become more prominent as threat actors have sought vectors to deliver malicious content or navigate a potential victim to a malicious domain.

Qakbot, a renowned threat actor specialising in phishing campaigns with the purpose of gaining initial access to networks, have been using HTML attachments and smuggling JavaScript within Scalable vector graphics (SVG).

This JavaScript is activated when a html attachment is clicked and it contains an entire zip folder which is downloaded onto the victim's machine.

The user is then prompted to interact with the file, typically through entering a password supplied either in the SVG or email.

After the zip file is unlocked, an .iso file is extracted which aims to infect the host with Qakbot.



Report all Fraud and Cybercrime to Action Fraud by calling 0300 123 2040 or online. Forward suspicious emails to Report SMS scams by forwarding the original message to 7726 (spells SPAM on the keypad).



The contents of blog posts on this website are provided for general information only and are not intended to replace specific professional advice relevant to your situation. The intention of East Midlands Cyber Resilience Centre (EMCRC) is to encourage cyber resilience by raising issues and disseminating information on the experiences and initiatives of others. Articles on the website cannot by their nature be comprehensive and may not reflect most recent legislation, practice, or application to your circumstances. EMCRC provides affordable services and Trusted Partners if you need specific support. For specific questions please contact us by email.


EMCRC does not accept any responsibility for any loss which may arise from reliance on information or materials published on this blog. EMCRC is not responsible for the content of external internet sites that link to this site or which are linked from it.

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