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Fake Solidity VSCode extension on Open VSX backdoors developers

BleepingComputer
·
Bill Toulas
·
Published Nov 3, 2025
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Updated

A remote access trojan dubbed SleepyDuck, and disguised as the well-known Solidity extension in the Open VSX open-source registry, uses an Ethereum smart contract to establish a communication channel with the attacker. Open VSX is a community-driven registry for extensions compatible with VS Code, which are popular with AI-powered integrated development environments (IDEs) like Cursor and Windsurf. The extension is still present on Open VSX as 'juan-bianco.solidity-vlang', albeit with a warning from the platform, and has been downloaded more than 53,000 times. When initially submitted on October 31st, the extension was harmless and received malicious capabilities with an update the next day, when the download count had already reached 14,000. According to a report from extension security platform Secure Annex, a notable feature in SleepyDuck is the use of Ethereum contracts to update its command-and-control (C2) server address and achieve long-term persistence. Even if the default C2 server at sleepyduck[.]xyz is taken down, the contract on the Ethereum blockchain allows the malware to remain functional. Since its submission to Open VSX with version 0.0.7 and until version 0.1.3 published on November 2nd, the juan-bianco.solidity-vlang package was downloaded 53,439 times and has only one 5-star rating from its author. It should be noted that author of the malic The malicious code activates on editor startup, when a Solidity file is opened, or when the user runs the Solidity ...

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Affected Software

1 affected component
Open VSX Solidity
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Frequently Asked Questions

1

What is the main topic of this article?

The article discusses a fake Solidity extension on Open VSX that backdoors developers using a remote access trojan called SleepyDuck.

2

What security implications are discussed in the article?

The article highlights how the malicious extension can compromise developer security through a remote access trojan disguised as legitimate software.

3

What product is primarily affected by this security issue?

The primary product affected is the Solidity extension for Visual Studio Code available on the Open VSX registry.

4

How does the SleepyDuck trojan establish communication with the attacker?

SleepyDuck uses an Ethereum smart contract to establish a communication channel with the attacker.

5

Who is targeted by the malicious Solidity extension on Open VSX?

The targeted individuals are developers who download and install the compromised Solidity extension from the Open VSX registry.

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