A flaw in the random number generator of certain hardware wallets allowed attackers to guess private keys and steal 594 bitcoin — worth roughly $38 million — in a 25-minute window. The incident, which investigators say was a targeted sweep rather than a broad attack, has raised fresh questions about the security of devices meant to be the gold standard for crypto storage.
How the bug worked
The vulnerability lay in the way the wallet generated seed phrases — the 12- or 24-word sequences used to recover funds. Normally, these seeds are supposed to be impossible to guess, drawn from a source of true randomness. But a coding error meant the random number generator produced predictable outputs under certain conditions. Attackers who reverse-engineered the firmware could narrow the possible seed space to a small enough set that brute-forcing became feasible.
Security researchers who analyzed the aftermath said the bug had likely been present for months before it was exploited. The wallet maker has not publicly identified itself, but users of several popular models have been urged to move funds to new wallets with updated firmware.
The 25-minute heist
On the day of the theft, the attackers executed a coordinated sweep. They targeted wallets whose seeds were generated during a specific timeframe when the random number generator was at its weakest. In less than half an hour, 594 BTC was transferred out of dozens of wallets into addresses controlled by the hackers. Blockchain data shows the stolen coins were then split into smaller amounts and moved through multiple mixers within hours.
Investigators are still tracing the funds, but they say the speed and precision of the operation suggest the attackers had prepared for weeks. They likely tested the vulnerability on their own devices before launching the real attack.
What users should do
Anyone using a hardware wallet that generates seeds via a random number generator should check with the manufacturer for a security advisory. If the wallet maker has issued a firmware update, install it immediately. For wallets that allow it, generating a new seed phrase using a trusted software tool or a hardware wallet with a verified random source is recommended.
The company behind the affected wallets has not yet released a full post-mortem. Users are advised to assume any wallet that hasn't been updated since the vulnerability was disclosed could still be at risk.
Blockchain forensics firms are monitoring the stolen funds. So far, none of the 594 BTC has been returned, and the attackers have not been identified.
