Hardware wallet manufacturers Trezor and Foundation have warned of a surge in phishing attempts trading on the Coldcard firmware exploit , with scammers chasing users' recovery phrases and pushing malicious downloads.
Trezor said it was already seeing an increase in phishing attempts following the disclosure, telling users to enter a wallet backup only on the device itself and reiterating that its own hardware is unaffected. Foundation said it had been made aware of emails impersonating the firm that push recipients toward fake websites and malicious downloads, adding that it will never ask for a recovery phrase or tell users to install software to secure a wallet.
Security firm Proofpoint documented a phishing campaign targeting Coldcard users on Monday. Emails sent from a spoofed Coldcard address invite recipients to complete a "coordinated hardware audit," a theme lifted from the security incident itself, and link to a cloned Coldcard site carrying a "Start Hardware Audit" button.
A COLDCARD hardware wallet vulnerability is being exploited by threat actors.
The reported firmware flaw has led to tens of millions worth of Bitcoin stolen.
We've observed social engineering w/ “hardware audit” themes impersonating #COLDCARD in email-based phishing campaigns. pic.twitter.com/1KSfZW3H2N
Clicking it pulls a batch file hosted on GitHub, which installs ScreenConnect, a legitimate remote-access tool. Proofpoint said that gives attackers a route to data and financial theft, or to follow-on malware such as ransomware.
The fake site also runs a customer service chat window. Proofpoint said a real person, not a bot, answers it and walks victims through the installation, assessing the breach as an effective social engineering lure because it “preys on the fear and concern” holders now have about their crypto security.
The Coldcard exploit stems from a March 2021 firmware build that drew wallet seeds from a software fallback instead of the device's hardware random number generator, leaving private keys guessable.
Galaxy Research has confirmed three waves of thefts since July 30 and puts high-confidence losses at 1,596 BTC , above $100 million. Including a fourth wave it suspects but has not confirmed with victims, it said the total could reach $130 million.
The firm's Head of Research Alex Thorn said Tuesday that at least 15 separate attackers are now exploiting the flaw, noting that every wave but the first was identified through victim reports. Coldcard manufacturer Coinkite has issued patched firmware and told affected users to move funds to newly generated seeds.
Phishing campaigns have used an array of methods to target hardware wallet owners. In February, Trezor and Ledger users were hit by a physical mail campaign impersonating the firms, complete with holograms and forged executive signatures, built around the same manufactured deadline. A counterfeit Ledger app drained millions from holders in April, and a March campaign used fake GitHub issues to lure developers onto a spoofed site.
Galaxy Research said the Coldcard exploit is ongoing and urged holders to move funds to a fresh seed or a custodian—giving the phishing lure a long potential shelf life.