I'm Unique, Just Like You: Human Side-Channels and Their Implications for Security and Privacy

Black Hat USA 2019

Presented by: Matt Wixey
Date: Wednesday August 07, 2019
Time: 13:30 - 14:20
Location: Lagoon GHI

Almost everything about us – our handwriting, DNA, faces, voices, fingerprints, even our eyes – can be used to distinguish us from the seven billion other people on the planet. These physical identifiers can allow law enforcement to trace back real-world crimes to offenders, and enable biometric authentication mechanisms. However, such identifiers are often irrelevant when it comes to attempting to track or disrupt threat actors.

In this talk, I will discuss, explore, and explain identifiers which are unintentional, non-physical, and generated as a result of human behaviours and activities, but which can still be used to uniquely identify and/or track individual users in the digital realm. I call these identifiers "human side-channels", and will explore how they work; how they can be used for both attack and defense; and how they can be countered.

I'll examine three human side-channels in particular: forensic linguistics; behavioural signatures; and cultural references. I will start by exploring the theories underpinning these side-channels, which are rooted in personality psychology and the concepts of consistency and distinctiveness as a result of our unique experiences, training, and feedback. I'll then explore how they work; walk through case studies and examples/demos of using them practically in security contexts; and discuss how they could be practically applied to investigate and track threat actors, in situations ranging from hostile social media profiles to post-compromise exfiltration and privilege escalation.

I'll also examine the privacy implications of each technique, and how such characteristics – which are much harder to recognise, obfuscate, or spoof – could be used to erode privacy. I'll go into detail regarding possible countermeasures to disguise your own human side-channels, and I'll wrap up by outlining some ideas for future research in these areas.

Matt Wixey

Matt Wixey leads technical research for the PwC Cyber Security practice in the UK, and is a PhD candidate at University College London. Prior to joining PwC, Matt led a technical R&D team for a law enforcement agency in the UK. His research interests include antivirus and sandboxing technologies, unconventional attack vectors, side-channels, and radio security.


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