EtherHiding Campaign Hides Banking Trojan C2 in Polygon Smart Contracts

Security researchers have detailed the EtherHiding campaign, which conceals command-and-control infrastructure inside smart contracts on the Polygon blockchain. The final payload is a malicious browser extension that functions as a banking trojan, intercepting credentials and two-factor codes from approximately 479 financial and cryptocurrency websites. Instead of embedding fixed addresses in its code, the malware queries an encrypted C2 server address from the smart contract, allowing operators to change destinations through low-cost blockchain transactions that bypass domain blocking. Infection begins when victims visit one of 31 compromised legitimate sites that inject JavaScript displaying a fake CAPTCHA prompt. The prompt instructs users to press Windows+R and execute a PowerShell command, a social engineering technique known as ClickFix that downloads the malicious scripts without exploiting any software vulnerability. The campaign has remained active from November 2025 through at least September 2026, demonstrating the resilience of blockchain-based infrastructure against traditional takedown methods.

BoletimSecTranslated from Portuguese

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Security researchers have detailed a campaign called EtherHiding that hides its command-and-control infrastructure inside smart contracts on the Polygon blockchain. The final payload is a malicious browser extension that operates as a banking trojan, targeting login credentials and two-factor authentication codes across roughly 479 financial and cryptocurrency websites.

Rather than hard-coding server addresses, the extension queries an encrypted C2 destination directly from the smart contract. Changing the target requires only an inexpensive blockchain transaction, rendering conventional domain blocking ineffective. The extension also records keystrokes, captures screenshots and screen video, and targets password managers and cryptocurrency wallets.

Initial access occurs through 31 compromised legitimate websites that inject JavaScript displaying a fake CAPTCHA. The prompt instructs the victim to press Windows+R and run a provided command, triggering PowerShell to download the malicious scripts. This ClickFix technique relies entirely on social engineering and does not exploit any software vulnerability.

The campaign has been active since November 2025, with its infrastructure remaining operational as of September 2026. Because the control address resides on the blockchain, disrupting the operation requires more than simply taking a domain offline.

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