WoofLocker Toolkit Hides Malicious Codes in Pictures to Run Tech Assist Scams

Aug 19, 2023THNMalvertising / Web site Safety

Cybersecurity researchers have detailed an up to date model of a sophisticated fingerprinting and redirection toolkit known as WoofLocker that is engineered to conduct tech help scams.

The subtle visitors redirection scheme was first documented by Malwarebytes in January 2020, leveraging JavaScript embedded in compromised web sites to carry out anti-bot and internet visitors filtering checks to serve next-stage JavaScript that redirects customers to a browser locker (aka browlock).

This redirection mechanism, in flip, makes use of steganographic tips to hide the JavaScript code inside a PNG picture that is served solely when the validation section is profitable. Ought to a consumer be detected as a bot or not fascinating visitors, a decoy PNG file with out the malicious code is used.

WoofLocker is often known as 404Browlock attributable to the truth that visiting the browlock URL immediately with out the suitable redirection or one-time session token ends in a 404 error web page.

The cybersecurity agency’s newest evaluation exhibits that the marketing campaign continues to be ongoing.


“The ways and strategies are very related, however the infrastructure is now extra sturdy than earlier than to defeat potential takedown makes an attempt,” Jérôme Segura, director of risk intelligence at Malwarebytes, said.

“It’s simply as troublesome to breed and research the redirection mechanism now because it was then, particularly in mild of recent fingerprinting checks” to detect the presence of digital machines, sure browser extensions, and safety instruments.

A majority of the websites loading WoofLocker are grownup web sites, with the infrastructure utilizing internet hosting suppliers in Bulgaria and Ukraine that give the risk actors stronger safety towards takedowns.

The first aim of browser lockers is to get focused victims to name for help to resolve (non-existent) laptop issues and achieve distant management over the pc to draft an bill that recommends affected people to pay for a safety answer to handle the issue.

“That is dealt with by third-parties by way of fraudulent name facilities,” Segura famous again in 2020. “The risk actor behind the visitors redirection and browlock will receives a commission for every profitable lead.”

The precise id of the risk actor stays unknown and there’s proof preparations for the marketing campaign have been underway as early as 2017.

“In contrast to different campaigns that depend on buying advertisements and enjoying whack-a-mole with internet hosting suppliers and registrars, WoofLocker is a really secure and low upkeep enterprise,” Segura mentioned. “The web sites internet hosting the malicious code have been compromised for years whereas the fingerprinting and browser locker infrastructure seems to be utilizing strong registrar and internet hosting suppliers.”

The disclosure comes as the corporate detailed a brand new malvertising an infection chain that includes utilizing bogus advertisements on search engines like google and yahoo to direct customers looking for distant entry packages and scanners to booby-trapped web sites that result in the deployment of stealer malware.


What units this marketing campaign aside is its potential to fingerprint guests utilizing the WEBGL_debug_renderer_info API to collect the sufferer’s graphics driver properties to kind actual browsers from crawlers and digital machines and exfiltrate the info to a distant server as a way to decide the subsequent plan of action.

“By utilizing higher filtering earlier than redirecting potential victims to malware, risk actors make sure that their malicious advertisements and infrastructure stay on-line longer,” Segura said. “Not solely does it make it tougher for defenders to determine and report such occasions, it additionally doubtless has an affect on takedown actions.”

The event additionally follows new analysis which found that web sites belonging to U.S. authorities businesses, main universities, {and professional} organizations have been hijacked during the last 5 years and used to push rip-off affords and promotions by way of “poison PDF” information uploaded to the portals.

Many of those scams are geared toward youngsters and try to trick them into downloading apps, malware, or submitting private particulars in alternate for non-existent rewards in on-line gaming platforms comparable to Fortnite and Roblox.

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