Clickjacking has lengthy been thought-about a “dumb” assault within the cybersecurity world. Historically, it entails putting an invisible body over a reputable web site to trick a consumer into clicking a button they didn’t intend to, like masking a “Delete Account” button with a faux “Play Video” overlay.
Nonetheless, a safety researcher referred to as Lyra has unveiled a classy new method dubbed “SVG clickjacking” that essentially adjustments the risk panorama.
A safety researcher has unveiled a novel exploitation method that essentially transforms how clickjacking assaults function, turning them from easy “hidden button” tips into complicated, interactive exploits able to studying display screen content material and executing logic.
Dubbed “SVG clickjacking” by its discoverer, the researcher referred to as Lyra (or rebane2001), the method leverages Scalable Vector Graphics (SVG) filters to create “sensible” overlays that may detect and reply to the state of a goal web site.
SVG Clickjacking Overlay (Supply: Lyra)
In contrast to conventional clickjacking, the place attackers merely overlay an invisible iframe to trick customers into clicking a button, this new technique permits the assault web page to “learn” pixels from the sufferer website and alter its personal interface based mostly on what the consumer sees.
SVG Clickjacking Illustration (Supply: Cybersecuritynews)
SVG Clickjacking Assault
The core of the vulnerability lies in the way in which fashionable browsers course of SVG filters corresponding to feDisplacementMap, feColorMatrix, and feComposite. Whereas these instruments are designed for graphical results like refractions or shade shifts, Lyra demonstrated that they are often repurposed to carry out logical operations.
By chaining these filters collectively, an attacker can construct functioning logic gates (AND, OR, XOR) instantly throughout the browser’s rendering engine. This successfully turns the SVG filter right into a primitive pc that may monitor a cross-origin iframe.
For instance, an assault might detect if a particular dialog field has appeared, if a checkbox is checked, or if purple error textual content is seen, after which dynamically replace the faux overlay to information the consumer by a multi-step course of.
Lyra demonstrated the method’s severity with a proof-of-concept assault towards Google Docs, which earned a $3,133.70 bounty from Google’s Vulnerability Reward Program.
Within the demo, the attacker tricked a consumer into producing a doc, typing a faux “captcha” right into a textual content field (which was really a Google Docs enter area), and clicking by a sequence of buttons.
The assault was notable as a result of it required the overlay to react to the doc’s state, hiding the faux enter field as soon as the consumer had efficiently “typed” the captcha, and displaying a brand new button solely when the doc was prepared.
“Up to now, particular person elements of such an assault might’ve been pulled off by conventional clickjacking… however the complete assault would’ve been method too lengthy and complicated to be real looking,” Lyra wrote.
Maybe essentially the most hanging software of SVG clickjacking is its means to exfiltrate information. The researcher confirmed how the method might learn delicate pixels from a goal website and encode that information right into a URL, which is then rendered as a scannable QR code utilizing the feDisplacementMap filter.
This creates a situation the place an attacker might immediate a consumer to “scan this code to confirm you’re human,” whereas the code really accommodates a URL with their stolen session information or non-public data embedded within the parameters.
This analysis marks a major escalation in “UI redress” assaults. By proving that SVG filters can act as a side-channel to learn cross-origin pixels and execute logic, the analysis means that merely counting on visible obscurity is not a adequate protection towards clickjacking.
As Lyra famous, the method permits for assaults which can be “interactive” and “responsive,” bypassing the blind guesswork that beforehand restricted the affect of such exploits.
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