North Korean WaterPlum Group Infects 30,000 Computers Across 100 Countries via Fake Coding Tests

The North Korean-linked group WaterPlum, also known as Contagious Interview, has infected at least 30,000 computers in more than 100 countries between December 2025 and July 2026. According to the Internet Crime Complaint Center (IC3), the operation moved at least $10.7 million in cryptocurrency to North Korea and compromised more than 7,000 wallets. Attackers pose as recruiters on social media and freelance platforms, luring software developers with nonexistent job offers that require downloading malicious files disguised as coding tests. The malware arsenal includes BeaverTail, InvisibleFerret, OtterCookie, OtterCandy, and StoatWaffle, with the latter hiding inside blockchain-themed projects and abusing Visual Studio Code configurations. Developers are specifically targeted because they often store production keys, wallets, and credentials on the same machines used for testing third-party code. Japanese authorities have dismantled laptop farms connected to the scheme that helped maintain the attackers' operational cover.

BoletimSecTranslated from Portuguese

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The North Korean-linked threat group WaterPlum, also tracked as Contagious Interview, has compromised at least 30,000 computers across more than 100 countries between December 2025 and July 2026.

According to the Internet Crime Complaint Center (IC3), operators moved at least US$10.7 million in cryptocurrency to North Korea. More than 7,000 wallets had funds or credentials stolen during the campaign.

The operation begins on social media and freelance platforms where actors pose as recruiters offering fake software development positions. Victims are asked to complete a coding task or solve a software problem, requiring them to download a file that installs the malware.

The group's toolkit includes BeaverTail, InvisibleFerret, OtterCookie, OtterCandy, and StoatWaffle. StoatWaffle is delivered inside blockchain-themed projects and abuses Visual Studio Code settings to execute code on the developer's machine.

Targeting developers is deliberate: these professionals frequently store production access keys, cryptocurrency wallets, and credentials on the same systems used to test untrusted code, turning a routine technical interview into a high-value entry point.

In Japan, authorities dismantled laptop farms linked to the scheme that supported the attackers' false professional personas and helped maintain persistent access to compromised systems.

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