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A chilling new threat has emerged from the world of open-source development — and it’s far more sophisticated than anything seen before. A seemingly harmless npm package named os-info-checker-es6 has been exposed as the centerpiece of an elaborate malware campaign. With cleverly hidden data and the abuse of cloud services like Google Calendar, this campaign raises the bar for supply chain attacks, demonstrating how threat actors are evolving in both stealth and ingenuity.
This discovery is not just another reminder to vet dependencies. It signals a deeper, systemic risk in the software supply chain, particularly for developers relying on npm packages. As the line blurs between legitimate tools and malicious implants, the open-source ecosystem faces one of its biggest security challenges to date.
Inside the Stealth Attack: How the Malware Was Uncovered
The npm package os-info-checker-es6 started out appearing completely innocent. Early versions performed simple OS queries and wrote files using install hooks without raising any red flags. However, beginning on March 22–23, newer versions introduced platform-specific Node.js binaries and changes to the install script that hinted at something more sinister.
Researchers found that the install script now imported a decode function from a native .node binary, which appeared to process a basic vertical bar character. However, that character was followed by a sequence of invisible Unicode variation selectors (from the range U+E0100 to U+E01EF) — symbols invisible to the human eye but capable of storing data using their low-byte values.
When analyzed, these Unicode symbols were revealed to be part of a low-byte steganography scheme, where each invisible character encoded a byte of data. This data, once decoded, produced a Base64-encoded string. In early versions, it contained nothing more than a simple line of JavaScript (console.log('Check');), but this acted as a priming mechanism for more complex payloads in later updates.
By May 7, with version 1.0.8, the package underwent a major transformation. The obfuscated payload had grown and now functioned as a network-focused loader. It reached out to a Google Calendar short link, using it as an indirect command-and-control (C2) endpoint. Once connected, it extracted a data-base-title attribute from the calendar event page, which contained a second-stage URL. From there, it downloaded and executed a more advanced payload — potentially encrypted and built to persist silently on infected systems.
Interestingly, at the time of inspection, the malicious server returned a harmless payload (process.exit(0)), suggesting the campaign was either dormant, terminated, or possibly able to detect security researchers and respond with decoy data.
The use of Google Calendar as a C2 intermediary is especially clever. It bypasses many security mechanisms and rides on the legitimacy of a trusted service. According to VeraCode researchers, this technique builds upon prior proof-of-concept work like the Google Calendar RAT (GCR), but now weaponized in a live campaign within the npm ecosystem.
The infected package had about 655 weekly downloads and had already been adopted as a dependency by at least four other packages — skip-tot, vue-dev-serverr, vue-dummyy, and vue-bit. These packages could be sleeper cells, ready to activate in future stages of the campaign.
What Undercode Say:
This malware campaign is a masterclass in layered deception — and a warning sign of where supply chain attacks are headed.
By blending invisible Unicode-based data encoding with cloud service manipulation, the attackers behind os-info-checker-es6 have demonstrated an unprecedented level of subtlety. Steganography isn’t new, but hiding it inside Unicode variation selectors within npm install scripts is a novel approach that eludes most automated scanners and code reviewers.
What makes this threat especially dangerous is its progressive delivery model. Initial versions seem harmless, allowing them to pass unnoticed and be adopted in other projects. Once embedded, the malware evolves silently, reaching out to remote servers for payloads that can change dynamically — or remain dormant until triggered. This design makes detection incredibly difficult and delays response time.
The use of Google Calendar as a makeshift C2 server further complicates defenses. Cloud services are trusted by nature and usually allowed through firewalls. By embedding the actual C2 instructions in a calendar event’s metadata, the attackers bypass traditional DNS or IP blacklisting tactics. It’s a smart way to exploit human trust in big tech platforms.
Also noteworthy is the multi-platform adaptation. The package dynamically loads platform-specific binaries, ensuring maximum compatibility while minimizing detection. Even when inspecting the install scripts, the payload only makes sense once the hidden Unicode characters are decrypted — making it virtually invisible to casual inspection or conventional code audits.
The scale of this campaign is still uncertain, but the fact that four other packages have already integrated this trojan hints at a coordinated operation, likely involving sleeper modules waiting for activation. This isn’t a one-off attack. It’s a persistent threat designed to establish long-term footholds within the software supply chain.
Defenders should now focus on:
Aggressively auditing install scripts and native modules in third-party packages.
Developing tooling that can detect hidden Unicode manipulation and steganographic encoding.
Monitoring for unusual cloud service requests during package installation.
Vetting package authorship and publication patterns for suspicious behavior.
This attack marks a turning point for open-source security. The days of simple typosquatting or obviously malicious packages are behind us. The threat landscape now includes full-fledged cyber-espionage tactics embedded within popular developer tools.
Fact Checker Results ✅
🔍 This campaign used invisible Unicode characters to hide its malicious payload
☁️ It exploited Google Calendar events as a covert channel for C2 communication
📦 Package downloads and dependency chains suggest a sleeper-style attack setup
Prediction 📡
This won’t be the last time Unicode steganography and trusted cloud services are used in supply chain attacks. In fact, this campaign is likely just the beginning of a broader trend where multi-stage loaders, invisible payloads, and cloud-based C2 channels become common tactics. Expect future npm and PyPI threats to adopt similar methods, blending into development ecosystems while staying one step ahead of traditional detection systems. Open-source repositories may soon become battlegrounds in cybersecurity’s next frontier.
References:
Reported By: cyberpress.org
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