A Fake Solidity Extension for Cursor Drained $500,000 From a Developer's Crypto Wallet

big oops verified Cursor Last verified Jul 17, 2026

TL;DR In July 2025, Kaspersky traced a roughly $500,000 crypto theft to a malicious 'Solidity Language' extension installed from the Open VSX registry that Cursor uses. The extension did nothing useful; it quietly ran a PowerShell payload and installed infostealer malware that harvested the victim's wallet credentials. The attackers won the search results by inflating the fake extension's install count.

Date: Jul 2025
Tools involved: Cursor
Impact: About $500,000 in cryptocurrency stolen from one blockchain developer; the fake extension's install count was inflated to as high as 2 million versus about 61,000 for the legitimate package.
Root cause: Cursor sources extensions from the Open VSX registry, whose search ranking was gamed with a fabricated install count and a fresh 'last updated' date so a malicious infostealer extension ranked above the real one.

What happened

In July 2025, Kaspersky reported that a blockchain developer in Russia lost roughly $500,000 in cryptocurrency after installing a malicious 'Solidity Language' extension for the Cursor AI IDE. Cursor is a VS Code fork built for AI-assisted development, and it pulls extensions from the Open VSX registry rather than Microsoft's marketplace.

The fake extension offered no real Solidity support. Once installed, it downloaded and ran a PowerShell-based payload that ultimately installed PureLogs, a Quasar-family infostealer. The malware harvested browser data and cryptocurrency wallet credentials, which is how the attacker reached the victim's funds.

The attackers won the search results by gaming Open VSX's ranking. They inflated the malicious package's install count to about 54,000 and set a more recent 'last updated' date, so it surfaced above the legitimate Solidity extension. After the first version was removed, the actor republished it and pushed the fake install count as high as 2 million, compared with about 61,000 for the real package, before it was pulled again following Kaspersky's report.

Kaspersky, BleepingComputer, and SC Media covered the case as a demonstration that the AI-IDE extension ecosystem can be gamed to target developers, especially those holding high-value crypto assets. The lesson is not about Solidity or Cursor specifically. It is that extension marketplaces are a supply chain, and install counts are not proof of trust.

Impact

One blockchain developer lost about $500,000 in cryptocurrency. The malicious extension provided no functionality but ran an infostealer that swept browser data and wallet credentials. Its reach came from ranking manipulation: the fake install count was inflated to roughly 54,000, then to as high as 2 million after a republish, against about 61,000 for the legitimate Solidity extension.

Root cause

Cursor installs extensions from the Open VSX registry, and that registry's search ranking could be gamed with a fabricated install count and a fresh 'last updated' timestamp. A developer searching for Solidity support saw the malicious package ranked first and trusted it. There was no technical exploit of Cursor itself. The failure was trusting a marketplace result whose popularity signals were fake.

How to not be this entry

Install extensions only from a publisher you can verify, and check the source repository and author rather than the install count. Inflated download numbers are exactly the signal attackers fake. Read the fix guide: Slopsquatting: the AI hallucinated an npm package and an attacker registered it
Keep hot cryptocurrency wallets and their credentials off the machine you use for development. Use a hardware wallet and a separate signing device so a compromised editor cannot reach your funds.
Treat the extension marketplace as a software supply chain. A new extension with a generic name and a suspiciously recent update date deserves scrutiny before it touches your editor.
Be suspicious of any extension that requests filesystem or shell access but provides no visible functionality. An extension that 'does nothing' is a red flag, not a dud.

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Frequently asked questions

How did a fake Cursor extension steal $500,000 in crypto?

In July 2025 a blockchain developer installed a malicious 'Solidity Language' extension for the Cursor AI IDE from the Open VSX registry. The extension ran a PowerShell payload that installed the PureLogs infostealer, which harvested browser data and cryptocurrency wallet credentials, letting the attacker drain roughly $500,000. The extension itself provided no real Solidity functionality.

Why did the malicious Solidity extension rank above the real one?

The attackers gamed the Open VSX registry that Cursor uses for extensions. They inflated the fake extension's install count to about 54,000 (and later as high as 2 million after republishing) and used a more recent 'last updated' date, which pushed it above the legitimate Solidity extension in search results. Install counts are trivially faked and are not proof that an extension is safe.

Was Cursor itself vulnerable, or was this the extension?

This was a malicious third-party extension, not a flaw in Cursor's own code. Cursor sources extensions from the Open VSX registry instead of Microsoft's marketplace, and that registry's ranking was manipulated to promote the malware. The safe takeaway is to verify extension publishers and treat any marketplace as a supply chain you have to vet.

How do I avoid malicious AI-IDE extensions?

Install extensions only from publishers you can verify, check the linked source repository and author, and ignore raw install counts because attackers inflate them. Keep cryptocurrency wallets and their credentials off your development machine, and be suspicious of any extension that asks for filesystem or shell access without offering visible functionality.

Sources

Related error guides

Slopsquatting: the AI hallucinated an npm package and an attacker registered it

Accidentally committed an API key to GitHub

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