AISEC > Security News > Fake Next.js Job Tests Backdoor Developers | Microsoft Defender
February 25, 2026 #malware Source: BleepingComputer 3 min read · 650 words

Fake Next.js job interview tests backdoor developer's devices

Підроблені тести для співбесід Next.js – бекдор на пристроях розробників

Timeline: When the Campaign Started

The malware campaign didn't appear overnight. According to BleepingComputer, Microsoft Defender detected this coordinated attack in February 2026, but the infrastructure had been operational for months before security teams caught on. Six months of undetected activity. That's a long runway for attackers to compromise developer machines and establish persistence.

Here's what we know about the timeline: threat actors registered fake repositories mimicking legitimate Next.js projects, posted fraudulent job listings on developer platforms, and crafted interview "tests" that looked professional enough to fool experienced engineers. By the time Microsoft Defender flagged the campaign, real developers had already fallen victim.

The Discovery

Microsoft Defender—which, for clarity, is the same security suite as Windows Defender, just rebranded—caught this through their threat intelligence network. The discovery wasn't random. Defenders spotted suspicious patterns in malware submissions and correlated them with job board activity and GitHub fork variations.

The real question is: how many developers downloaded these fake repositories thinking they were practicing for interviews with legitimate companies? Most victims probably didn't realize they'd been compromised immediately.

Microsoft Defender's cyber security infrastructure flagged multiple malicious files and command-and-control communications. Their vulnerability management systems tracked the attack vectors, logging each infection attempt. And then security researchers dug deeper.

Technical Analysis

What's actually happening here is sophisticated social engineering wrapped in technical legitimacy.

Attackers created repositories that looked nearly identical to actual Next.js projects—same naming conventions, similar documentation, credible-looking code samples. They posted job listings on platforms developers actually use, offering interview "tests" to candidates. These tests? Downloads that appeared to be legitimate coding challenges but contained backdoor payloads.

Once installed on a developer's machine, the malware established persistent access. We're talking about compromised development environments where source code lives, where API keys get stored, where authentication tokens sit in plain sight. This isn't ransomware that encrypts your files and demands payment. This is worse. This is espionage infrastructure.

The backdoors allowed attackers to steal credentials, exfiltrate source code, and potentially inject malicious code into the developer's actual projects—meaning the compromise could cascade downstream to their employers' applications and end users. One infected developer becomes a supply chain vulnerability.

Microsoft Defender threat detection flagged the malicious binaries, but the timing matters. By then, some developers had already been running compromised code in their primary development environments.

Damage Assessment

BleepingComputer didn't disclose exact victim counts, which raises obvious questions about containment and notification. How many developers got infected? Were they all notified? Did their employers know their codebases were potentially compromised?

The impact extends beyond individual machines.

Any developer who pulled malicious code into their projects could've inadvertently distributed backdoors to their organizations. If those developers worked for software companies, the supply chain risk multiplies. Enterprise customers of those companies face potential exposure. This creates nested layers of vulnerability.

What makes this particularly nasty: most organizations running Microsoft Defender vulnerability management only discover this kind of incident after the fact. Vulnerability management dashboards catch known CVEs and misconfigurations. They don't catch sophisticated social engineering that weaponizes job interviews.

Mitigation

First, the obvious: verify projects before cloning or downloading. Check repository creation dates. Look for activity patterns. Real Next.js projects have years of commit history and thousands of stars. Fake ones won't.

Second, scrutinize job interview processes. Legitimate companies conduct interviews through secure channels and don't ask you to download executable files from external sources. Period.

For developers who think they might've been affected: scan your machine immediately using Microsoft Defender or equivalent endpoint protection. Review your git commit history for suspicious changes. Check browser history for unauthorized access. Change all credentials.

Organizations need to run comprehensive endpoint scans across development teams. Microsoft Defender vulnerability management (MDVM) tools can help identify which machines downloaded suspicious files, though you'll need to correlate that with actual breach indicators.

And frankly, this should've been caught sooner. The infrastructure was live for months. GitHub and job platforms have automated detection systems. Six months is unacceptable.

Developers: trust your instincts. If something feels off about an interview process or a repository, it probably is.

Read original article →

// FAQ

Is Microsoft Defender the same as Windows Defender?

Yes. Microsoft rebranded Windows Defender as Microsoft Defender in 2020. It's the same security suite now integrated across Windows, Mac, and enterprise environments, with expanded features including cyber security training and threat management.

How do I know if I downloaded the malicious Next.js repository?

Check your git clone history and recent downloads for Next.js repositories with unusual names or timestamps. Run a full scan with Microsoft Defender or your endpoint protection tool. If you participated in job interviews that involved downloading code tests, investigate those sources immediately.

What should developers do if they suspect their machine was compromised?

Immediately scan with Microsoft Defender, rotate all credentials and API keys, audit your git commit history for unauthorized changes, and notify your employer's security team. If your code was compromised, alert any organizations using your software.

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