A group of academics from the New Jersey Institute of Technology (NJIT) has warned of a novel technique that could be used to defeat anonymity protections and identify a unique website visitor.
“An attacker who has complete or partial control over a website can learn whether a specific target (i.e., a unique individual) is browsing the website,” the researchers said. “The attacker knows this target only through a public identifier, such as an email address or a Twitter handle.”
The cache-based targeted de-anonymization attack is a cross-site leak that involves the adversary leveraging a service such as Google Drive, Dropbox, or YouTube to privately share a resource (e.g., image, video, or a YouTube playlist) with the target, followed by embedding the shared resource into the attack website.
This can be achieved by, say, privately sharing the resource with the target using the victim’s email address or the appropriate username associated with the service and then inserting the leaky resource using an <iframe> HTML tag.
In the next step, the attacker tricks the victim into visiting the malicious website and clicking on the aforementioned content, causing the shared resource to be loaded as a pop-under window (as opposed to a pop-up) or a browser tab — a method that’s been used by advertisers to sneakily load ads.
This exploit page, as it’s rendered by the target’s browser, is used to determine if the visitor can access the shared resource, successful access indicating that the visitor is indeed the intended target.
The attack, in a nutshell, aims to unmask the users of a website under the attacker’s control by connecting the list of accounts tied to those individuals with their social media accounts or email addresses through a piece of shared content.
In a hypothetical scenario, a bad actor could share a video hosted on Google Drive with a target’s email address, and follow it up by inserting this video in the lure website. Thus when visitors land on the portal, a successful loading of the video could be used as a yardstick to infer if their victim is one among them.