Loading story…
A sophisticated remote access trojan (RAT) named SleepyDuck has been distributed through malicious extensions in the Open VSX registry, targeting developers using code editors such as Cursor and Visual Studio Code. The extension, initially published as a benign library (juan-bianco.solidity-vlang version 0.0.7), was later updated to include malicious capabilities in version 0.0.8 after accumulating over 14,000 downloads. Once installed, the malware activates when a new code editor window is opened or a .sol file is selected, gathering system information and exfiltrating it to a remote server. SleepyDuck employs sandbox evasion techniques and leverages Ethereum smart contracts to dynamically update its command and control (C2) address, ensuring persistence even if the original server is taken down.
The extension is configured to poll for new commands every 30 seconds and can reach fallback Ethereum RPC endpoints to retrieve updated C2 details if necessary. Researchers have observed that the extension masquerades as a legitimate helper tool, but its activation logic and use of lock files reveal its malicious intent. The campaign highlights the growing threat of supply chain attacks via IDE extension marketplaces, with previous incidents resulting in significant cryptocurrency losses for developers. Security experts urge vigilance when installing third-party extensions and recommend monitoring for suspicious activity related to code editor plugins.
Trace attribution and downstream blast radius.
3 events from the most recent confirmed update back to the earliest known activity.
Follow-up reporting detailed that SleepyDuck used Ethereum-related infrastructure or mechanisms to help keep its command-and-control server reachable, adding new technical insight into the malware's resilience. Additional coverage also described the extension as a fake Solidity package that backdoored developers.
Security researchers published findings on the SleepyDuck malware campaign, describing how a malicious Open VSX extension was being used to compromise developers through Cursor/Open VSX ecosystems. The disclosure established the campaign and its developer-focused infection vector.
A malicious Open VSX extension masquerading as a Solidity-related VS Code tool was made available to developers, targeting users of Cursor and other editors that can consume Open VSX packages. The extension functioned as a backdoor and malware delivery mechanism.
Vulnerabilities, threat actors, malware, products, organizations, breaches, and observables Mallory has linked to this story. Indicator values are masked here and available in full in the app.
Indicator values are masked on this page. See the values in Mallory Domains, IPs, hashes, and URLs are exportable to your SIEM.
See attribution and downstream blast radius, and whether this package or vendor reaches your builds.
3 references tracked. Mallory keeps watching after this page renders.
thehackernews.com
Open sourcebleepingcomputer.com
Open sourcesecureannex.com
Open sourceMap indicators from this story to your assets and identify affected systems in minutes.
Every observed campaign, victim, and pivot linked to actors named in this story.
Malware, exploits, and IOCs connected to the activity described here.
YARA, Sigma, and Snort rules deployed to your SIEM as soon as they’re published.
Get matching new stories delivered to your team as they break — not the next morning.
Ask questions about this story and take action on the answers.
Other stories Mallory is tracking that overlap on entities, sources, or topic labels.
Security researchers have uncovered a coordinated campaign by the threat actor group TigerJack, which targets developers by publishing malicious extensions on both Microsoft's Visual Studio Code (VSCode) Marketplace and the OpenVSX registry. The campaign involves at least 11 different extensions distributed across multiple publisher accounts, with some extensions accumulating over 17,000 downloads before being removed from the official VSCode Marketplace. Despite removal from Microsoft's platform, these extensions remain active and available on the OpenVSX marketplace, which is used by alternative VSCode-compatible editors such as Cursor and Windsurf. The malicious extensions serve various purposes, including exfiltrating developers' source code, mining cryptocurrency using the host's resources, and maintaining persistent remote access. For example, the 'C++ Playground' extension registers a listener to capture and exfiltrate C++ source code in near real-time, while the 'HTTP Format' extension secretly runs a CoinIMP cryptominer in the background, consuming the host's processing power without restrictions. Some variants of the extensions are capable of fetching and executing remote JavaScript code, allowing TigerJack to dynamically update their payloads and potentially deploy additional threats such as credential stealers, ransomware, or API-harvesting scripts. The campaign demonstrates a high level of persistence, with TigerJack repeatedly re-uploading the same malicious code under new names and accounts after takedowns. The extensions are designed to appear as legitimate developer tools, increasing the likelihood of installation by unsuspecting users. The use of OpenVSX as a distribution channel poses a significant risk, as it is less regulated than Microsoft's marketplace and serves as the default for several popular IDEs. Researchers from Koi Security have been actively tracking the campaign and have highlighted the ongoing threat posed by these extensions, especially given their ability to maintain remote control and adapt their functionality without requiring updates. The campaign underscores the risks associated with third-party extension marketplaces and the importance of vetting and monitoring developer tools for malicious behavior. The technical sophistication of the extensions, particularly their ability to execute remote code and evade detection, raises concerns about long-term supply chain compromise within the developer ecosystem. Organizations and individual developers are advised to review installed extensions, monitor for suspicious activity, and prioritize security hygiene when sourcing tools from community-driven marketplaces. The continued presence of these extensions on OpenVSX, despite removal from the official VSCode Marketplace, highlights the challenges in fully eradicating such threats from the software supply chain. Security experts warn that the campaign is ongoing, with TigerJack actively seeking new ways to distribute their malicious payloads and compromise developer environments.
Jun 29, 2026
Security researchers reported **malicious Visual Studio Code extensions** being used as a software supply-chain vector to compromise developer workstations. One campaign impersonated a viral AI coding assistant (“**ClawdBot**”) via a fake extension (“ClawdBot Agent”) that appeared legitimate and even functioned as an AI assistant by integrating real APIs (e.g., OpenAI/Anthropic/Google), while **silently dropping malware on Windows at VS Code startup**. The observed payload delivery used camouflage filenames such as `Lightshot.exe` (and references to `Lightshot.dll`) and an Electron-style bundle name `Code.exe`, indicating an effort to blend into common developer tooling and evolve the dropper over time. A separate finding described an **Open VSX** extension masquerading as a popular **Angular Language Service** for VS Code, which bundled legitimate dependencies (e.g., `@angular/language-service` and `typescript`) alongside a **malicious loader** that activates when users open HTML or TypeScript files (`onLanguage:html`, `onLanguage:typescript`). The loader decrypts an embedded payload using **AES-256-CBC** (Node.js `crypto`), with a hardcoded IV and a large hex-encoded ciphertext, then delays and executes the decrypted code—behavior consistent with staged malware delivery and potential worm-like propagation through widely installed editor extensions.
Jun 29, 2026
A supply-chain compromise of the **Open VSX Registry** led to malicious updates being pushed to legitimate Visual Studio Code extensions after attackers gained access to a developer’s publishing credentials (likely via a leaked token or other unauthorized access). Reporting indicates four established extensions from the `oorzc` publisher were trojanized and distributed via Open VSX before being removed, with prior legitimate adoption measured in the tens of thousands of downloads and subsequent exposure affecting downstream developer environments. The injected payload delivered the **GlassWorm** malware/loader, which executes via obfuscated JavaScript embedded in the extension and includes environment checks (notably avoiding execution on **Russian-locale** systems). Technical details describe a multi-stage loader with capabilities aligned to credential and data theft, including macOS credential and cryptocurrency wallet targeting, and use of techniques such as **EtherHiding** to retrieve command-and-control infrastructure dynamically; defenders are advised to identify and remove affected extension versions and review developer endpoints for signs of compromise and credential/token leakage.
Jun 29, 2026