The e-commerce website of weapons manufacturer Smith & Wesson has been targeted by a Magecart payment card-skimming group that’s been using lookalike domain names to impersonate payment anti-fraud company Sanguine Security.

The Smith & Wesson website was compromised with a JavaScript-based skimmer last Wednesday, Nov. 27 – in time to steal card information for any purchases made during the Black Friday shopping period, Sanguine Security reported in a Dec. 2 blog post that detailed the ongoing campaign.

According to Sanguine, smith-wesson.com was just one of several “high-profile” sites to be compromised just prior to Black Friday by the same actor, which has been registering malicious domains such as sansec.us and sanguinelab.net in order to appear affiliated with Sanguine protection services. During the registration process, the actor even fraudulently used the same of Sanguine Security researcher Willem de Groot and entered a fake address in Amsterdam, the country where Sanguine is located.

“An untrained eye would look at that information and conclude that the domain was legitimate,” said Jarrod Overson, director of engineering at Shape Security, in emailed comments. “Attackers are becoming wise to the products that claim to be able to detect and mitigate Magecart-style attacks and are trying to blend in with them.”

Not all of the malware used in the Black Friday skimmer attacks featured a Sanguine-like domain, but “all of the big ones share identical code and infrastructure,” said the blog post, authored by de Groot.

The actor behind this skimmer went to great lengths to conceal its activity and frustrate security researchers, using multiple anti-reverse-engineering methods, a three-stage loader and four layers of JavaScript obfuscation. According to Sanguine, the skimmer’s loader serves up only benign code until the checkout process begins. Additionally, the skimmer only activates when the website visitor has a U.S.-based IP address and a non-Linux browser, and is not using the Amazon Web Services platform.

When the skimmer script does load, the victim views a fake payment form. Information entered onto this form finds it way back to the attackers via an exfiltration process.

BleepingComputer yesterday reported that it was able to independently verify Sanguine’s findings.

“The Magecart attack [and its vectors] are well known for almost a decade, but now their sophistication and complexity are rapidly evolving, making it an arduous task to detect them,” said Ilia Kolochenko, founder and CEO of ImmuniWeb. Oftentimes, malicious scripts will remain unnoticed by automated security scanning, disguising themselves as innocent third-party JavaScript. Given the multitude of external content on modern web pages, especially on the e-commerce websites, it’s extremely complicated to maintain an update inventory of legitimate external scripts and trackers.

“This incident is another reminder of why Magecart attacks continue to lurk on e-commerce websites and evade detection for weeks, or even months,” said Ameet Naik, security evangelist at PerimeterX. “The malicious script doesn’t reveal itself until specific conditions are met. This is done deliberately so that the malicious script will only run on user’s computers, and appear harmless to site scanners, which typically run on Linux servers and on cloud platforms such as AWS.”

“While scanning is a useful step in ensuring website integrity, it’s not sufficient to detect dynamic digital skimming scripts that only manifest themselves on actual users’ computers,” Naik continued. “Detecting these require real-time behavioral analysis that can catch malicious scripts as they deviate from known good execution patterns.”