Hardware wallet provider Trezor has confirmed unauthorized use of its third-party email provider has been behind a spate of malicious emails sent to users over the past 12 hours.

“We’ve detected an unauthorized email impersonating Trezor sent from a third-party email provider we use,” the hardware wallet provider explained on Jan. 24.

Security Alert

We've detected an unauthorized email impersonating Trezor sent from a third-party email provider we use.

If you received a suspicious email with the subject line 'Assets undergoing upgrade' from the ID: noreply@trezor.io, please do not click any links or… pic.twitter.com/RqQnQkB4hX

— Trezor (@Trezor) January 24, 2024

The malicious email, sent from “noreply@trezor.io” instructs users to upgrade their “network” or face losing their funds, providing them with a malicious link that leads to a webpage to have them enter their seed phrase.

Trezor hasn’t confirmed whether any users lost funds from the phishing attempt, nor has Cointelegraph seen any X posts suggesting a Trezor user has fallen victim to the scam.

However, Trezor confirmed it managed to “deactivate the malicious link," and said user funds remain safe as long as the user didn’t enter their recovery seed. For those that did, Trezor urges users to transfer their funds to a new wallet immediately.

Trezor said its investigation so far points to an unauthorized individual accessing its database of email addresses for its newsletter subscribers and using a third-party email service that Trezor uses to send the malicious email.

The unauthorized email impersonating Trezor using our domain addressed subscribers to our newsletter.

If you have not disclosed your 12 or 24-word recovery seed through any online form, your assets remain secure.

If you have entered your recovery seed in any form, particularly…

— Trezor (@Trezor) January 24, 2024

Interestingly, only days earlier, email marketing software firm MailerLite confirmed a cybersecurity incident  on Jan. 23, which led to a string of phishing emails using branded domains, including those owned by Cointelegraph, WalletConnect, and Token Terminal. The attacks have resulted in losses of over $3.3 million via phishing attacks. However, it is not clear whether Trezor uses the same email domain provider.

Others believe the recent attack is related to a recent  security breach of Trezor’s support portal, which had exposed the contact information of nearly 66,000 users on Jan. 17.

“No other data were compromised. We immediately restricted access to all unauthorized actors and are now contacting all affected users,” Trezor said at the time.

Digital asset lawyer Joe Carlasare revealed he personally received the phishing email in a Jan. 24 X post, describing it as a "sophisticated scam."

Related: Trezor releases new hardware wallet and metal private key backup

In February last year, Trezor cautioned users about a phishing attack designed to steal investor funds by making them enter the wallet’s recovery phrase on a fake Trezor website.

A few months later, in May, cybersecurity firm Kaspersky observed that a fake hardware wallet impersonating Trezor had hit the market. The fraudsters would then attempt to steal funds via a replaced microcontroller, which enabled them to take over control of a user’s private keys, the security firm explained.

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