Long-Running NPM Malware Campaign Accumulates 40,000 Downloads

Summary

A long-running NPM supply chain campaign, dubbed MALFEX, has distributed malware including Overlord RAT and infostealers through at least eight malicious packages since August 2023. While some malicious packages have been removed, others remained installable, with one package, function-flag, accumulating over 37,000 downloads without advisories. The campaign employs multiple delivery paths, targeting Windows systems with capabilities ranging from remote control to data theft from browsers and cryptocurrency wallets.

Full text

Malicious packages published as part of a long-running NPM supply chain campaign have accumulated over 40,000 downloads, Checkmarx reports. Dubbed MALFEX and distributing malware such as the Overlord RAT and infostealers, the campaign has been ongoing since August 2023, when the threat actor published its first package. To date, the threat actor has published 12 packages, eight of which are malicious. Five have been removed from the registry, but three were still installable as of October 1, namely function-flag, function-color, and cdn-img-fetch. According to Checkmarx, function-flag deserves special attention: it has been malicious since July 2025, has more than 37,000 downloads, and no advisory flags it as malicious. Open Source Vulnerabilities (OSV) advisories have been published for six malicious packages: tlxbnhd, tldriver, mxdriver, img-to-native, native-runner, and cdn-img-fetch. However, the entry for cdn-img-fetch covers only two of its four malicious iterations. Checkmarx identified three independent delivery paths used in the campaign, noting that they do not share infrastructure, although they are linked to the same threat actor.Advertisement. Scroll to continue reading. The first involves loaders for the Overlord RAT and obfuscated scripts executed during npm install. While the scripts can be launched on Windows, macOS, and Linux, the payload only works on Windows systems. The Overlord RAT provides the operator with monitoring and control capabilities, including screen capture, keylogging, window monitoring, remote shell access, file search, and a hidden desktop to perform malicious activities without detection. As part of the second path, malicious code is executed when the package is loaded, to drop the Node.js information stealer ‘movinlike’ on the victims’ machines. The malware targets eight Discord clients, seven popular browsers, and cryptocurrency wallets for data theft. The third path is the longest-running part of the campaign. It involves a separate downloader in each malicious version of function-flag, designed to fetch a payload from a different location. According to Checkmarx, the infection routine is implemented so that the package installation could complete even if the payload download fails. The routine fails silently on macOS and Linux, meaning that only Windows systems are affected. “No legitimate or widely used packages depend on any operator package, so exposure is limited to systems that installed these package names directly. We found no geographic or organizational targeting; anyone who installs the stealer becomes a target,” Checkmarx notes. Related: Linux Backdoor Abuses STUN Protocol, Exploits Dozens of Flaws Related: macOS Users Targeted by Fake Zoom Installer Carrying CloudSyncD Backdoor Related: Daemon Tools Hackers’ NeedyMantis Malware Dissected by Microsoft Related: New x47.c Windows Botnet Weaponizes xAI Grok, AI API Draining Written By Ionut Arghire Ionut Arghire is an international correspondent for SecurityWeek. Daily Briefing Newsletter Subscribe to the SecurityWeek Email Briefing for the latest cybersecurity threats, trends, and expert insights. More from Ionut Arghire Alleged ShinyHunters Leader Arrested in JordanFortra Patches Critical Vulnerabilities in BoKSIn Rare Move, Alleged Iranian State Hacker Extradited to USWarlock Expands SharePoint Exploitation in Critical Infrastructure AttacksExploited Fortinet FortiMail Zero-Day Calls for Urgent ActionZimbra Vulnerability Exploited in the Wild Prior to Public DisclosureZammad Zero-Days Exploited in AI-Powered DIVD Hack500,000 Active Credentials Left Exposed on GitHub Latest News Apple to Tighten Full Disk Access Controls in macOS Amid AI RisksCybersecurity M&A Roundup: 39 Deals Announced in September 20268.8 Million Impacted by Data Breach at Denmark’s Central Person RegisterSocial Engineering Detection Moves Into the Live ConversationGoogle Narrows Open Source Bug Bounty Amid Wave of Invalid Automated ReportsLinux Backdoor Abuses STUN Protocol, Exploits Dozens of Flaws250,000 Impacted by Data Breaches at New Jersey, Texas Healthcare FirmsExploitation Hits Rejetto HFS Vulnerability Discovered by AI Trending Daily Briefing NewsletterSubscribe to the SecurityWeek Email Briefing to stay informed on the latest threats, trends, and technology, along with insightful columns from industry experts. Webinar: Securing AI Agents, MCPs, and AI Automations October 7, 2026 Learn how to address potential risks and not restrict AI adoption in your organization. See what a centralized AI gateway is and how it works in practice. Register Virtual Event: Zero Trust & Identity Strategies Summit 2026 October 14, 2026 Join as we decipher the world of zero trust and share war stories on securing an organization by eliminating implicit trust and continuously validating every stage of a digital interaction. Register People on the MoveChip Wentz has been appointed as SVP & CISO at Keurig Dr Pepper Inc.Lumen Technologies has named Kim Keever as CSO.Quantum Secure Encryption Corp. has appointed Joseph Hall as CIO.More People On The MoveExpert Insights AI Has Changed Attack Speed, Not Security Fundamentals As AI accelerates vulnerability discovery and exploitation, so-called virtual patching still comes down to defense-in-depth and strong application security fundamentals. (Joshua Goldfarb) Four Cyber Threats Harboring Big Plans for the Future - AI, supply-chain exposure, quantum computing and geopolitical conflict are testing security programs. Preparing for disruption must become part of day-to-day operations. (Steve Durbin) Begin at the End: How to Enable Agentic Remediation Agentic remediation is not an act of faith. We are talking about fixing known problems, not judgment calls about unfamiliar risk. (Nadir Izrael) “We Think the Security Control Is Working” Is No Longer Good Enough Point-in-time audits and sampled assessments offer only snapshots; continuous control monitoring provides evidence that security controls are working today. (Sravish Sridhar) This Key Will Self-Destruct: An Open Standard for Revocable API Keys Every leaked credential should be dead, or dying, within sixty seconds of being found. Here's a proposal to make that the default. (Matt Honea) Flipboard Reddit Whatsapp Whatsapp Email

Indicators of Compromise

• malware — Overlord RAT
• malware — movinlike

Entities