Unit 42 details a Russian cyberespionage campaign targeting Zimbra webmail servers using JavaScript injection to steal credentials.

The post Russian Global Webmail Espionage appeared first on Unit 42.

Unit 42 discusses the supply chain attack targeting Axios. Learn about the full attack chain, from the dropper to forensic cleanup.

The post Threat Brief: Widespread Impact of the Axios Supply Chain Attack appeared first on Unit 42.

We discuss a novel AI-augmented attack method where malicious webpages use LLM services to generate dynamic code in real-time within a browser.

The post The Next Frontier of Runtime Assembly Attacks: Leveraging LLMs to Generate Phishing JavaScript in Real Time appeared first on Unit 42.

Researchers have been tracking a Magecart campaign that targets several major payment providers, including American Express, Diners Club, Discover, and Mastercard.

Magecart is an umbrella term for criminal groups that specialize in stealing payment data from online checkout pages using malicious JavaScript, a technique known as web skimming.

In the early days, Magecart started as a loose coalition of threat actors targeting Magento‑based web stores. Today, the name is used more broadly to describe web-skimming operations against many e‑commerce platforms. In these attacks, criminals inject JavaScript into legitimate checkout pages to capture card data and personal details as shoppers enter them.

The campaign described by the researchers has been active since early 2022. They found a vast network of domains related to a long-running credit card skimming operation with a wide reach.

“This campaign utilizes scripts targeting at least six major payment network providers: American Express, Diners Club, Discover (a subsidiary of Capital One), JCB Co., Ltd., Mastercard, and UnionPay. Enterprise organizations that are clients of these payment providers are the most likely to be impacted.”

Attackers typically plant web skimmers on e-commerce sites by exploiting vulnerabilities in supply chains, third-party scripts, or the sites themselves. This is why web shop owners need to stay vigilant by keeping systems up to date and monitoring their content management system (CMS).

Web skimmers usually hook into the checkout flow using JavaScript. They are designed to read form fields containing card numbers, expiry dates, card verification codes (CVC), and billing or shipping details, then send that data to the attackers.

To avoid detection, the JavaScript is heavily obfuscated to and may even trigger a self‑destruct routine to remove the skimmer from the page. This can cause investigations performed through an admin session to appear unsuspicious.

Besides other methods to stay hidden, the campaign uses bulletproof hosting for a stable environment. Bulletproof hosting refers to web hosting services designed to shield cybercriminals by deliberately ignoring abuse complaints, takedown requests, and law enforcement actions.

How to stay safe

Magecart campaigns affect three groups: customers, merchants, and payment providers. Because web skimmers operate inside the browser, they can bypass many traditional server‑side fraud controls.

While shoppers cannot fix compromised checkout pages themselves, they can reduce their exposure and improve their chances of spotting fraud early.

A few things you can protect against the risk of web skimmers:

• Use virtual or single‑use cards for online purchases so any skimmed card number has a limited lifetime and spending scope.
• Where possible, turn on transaction alerts (SMS, email, or app push) for card activity and review statements regularly to spot unsolicited charges quickly.
• Use strong, unique passwords on bank and card portals so attackers cannot easily pivot from stolen card data to full account takeover.
• Use a web protection solution to avoid connecting to malicious domains.

Pro tip: Malwarebytes Browser Guard is free and blocks known malicious sites and scripts.

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We don’t just report on threats—we remove them

Cybersecurity risks should never spread beyond a headline. Keep threats off your devices by downloading Malwarebytes today.

Researchers have been tracking a Magecart campaign that targets several major payment providers, including American Express, Diners Club, Discover, and Mastercard.

Magecart is an umbrella term for criminal groups that specialize in stealing payment data from online checkout pages using malicious JavaScript, a technique known as web skimming.

In the early days, Magecart started as a loose coalition of threat actors targeting Magento‑based web stores. Today, the name is used more broadly to describe web-skimming operations against many e‑commerce platforms. In these attacks, criminals inject JavaScript into legitimate checkout pages to capture card data and personal details as shoppers enter them.

The campaign described by the researchers has been active since early 2022. They found a vast network of domains related to a long-running credit card skimming operation with a wide reach.

“This campaign utilizes scripts targeting at least six major payment network providers: American Express, Diners Club, Discover (a subsidiary of Capital One), JCB Co., Ltd., Mastercard, and UnionPay. Enterprise organizations that are clients of these payment providers are the most likely to be impacted.”

Attackers typically plant web skimmers on e-commerce sites by exploiting vulnerabilities in supply chains, third-party scripts, or the sites themselves. This is why web shop owners need to stay vigilant by keeping systems up to date and monitoring their content management system (CMS).

Web skimmers usually hook into the checkout flow using JavaScript. They are designed to read form fields containing card numbers, expiry dates, card verification codes (CVC), and billing or shipping details, then send that data to the attackers.

To avoid detection, the JavaScript is heavily obfuscated to and may even trigger a self‑destruct routine to remove the skimmer from the page. This can cause investigations performed through an admin session to appear unsuspicious.

Besides other methods to stay hidden, the campaign uses bulletproof hosting for a stable environment. Bulletproof hosting refers to web hosting services designed to shield cybercriminals by deliberately ignoring abuse complaints, takedown requests, and law enforcement actions.

How to stay safe

Magecart campaigns affect three groups: customers, merchants, and payment providers. Because web skimmers operate inside the browser, they can bypass many traditional server‑side fraud controls.

While shoppers cannot fix compromised checkout pages themselves, they can reduce their exposure and improve their chances of spotting fraud early.

A few things you can protect against the risk of web skimmers:

• Use virtual or single‑use cards for online purchases so any skimmed card number has a limited lifetime and spending scope.
• Where possible, turn on transaction alerts (SMS, email, or app push) for card activity and review statements regularly to spot unsolicited charges quickly.
• Use strong, unique passwords on bank and card portals so attackers cannot easily pivot from stolen card data to full account takeover.
• Use a web protection solution to avoid connecting to malicious domains.

Pro tip: Malwarebytes Browser Guard is free and blocks known malicious sites and scripts.

---

We don’t just report on threats—we remove them

Cybersecurity risks should never spread beyond a headline. Keep threats off your devices by downloading Malwarebytes today.

Self-replicating worm “Shai-Hulud” has compromised hundreds of software packages in a supply chain attack targeting the npm ecosystem. We discuss scope and more.

The post "Shai-Hulud" Worm Compromises npm Ecosystem in Supply Chain Attack (Updated November 26) appeared first on Unit 42.

I like webapps, don’t you? Webapps have got to be the best way to learn about security. Why? Because they’re self-contained and so very transparent. You don’t need a big […]

The post Webcast: Free Tools! How to Use Developer Tools and Javascript in Webapp Pentests appeared first on Black Hills Information Security, Inc..

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Matthew Toussain // PowerShell is dead… well dying, kind of. JavaScript interpreters, on the other hand, are everywhere, and they are far from confined to the web browser. Join Matt […]

The post WEBCAST: JavaScript Weaponized appeared first on Black Hills Information Security, Inc..