Millions of dollars worth of cryptocurrency is believed to have been stolen as part of a distributed-denial-of-service attack targeting servers used by popular bitcoin wallet service Electrum.

The attack, a new version of an attack targeting Electrum in December, has the ultimate aim of tricking users into downloading a malicious version of the Electrum wallet that can then be used to steal cryptocurrency. The hackers do this by introducing their own Electrum servers with the malicious code to the network in an attempt to trick users into connecting to it.

Where this new attack differs is that those behind the attack are running a DDoS campaign against legitimate Electrum servers, knocking them offline so that only their servers are open to connection. The attacker is reported to be throwing as much as 25 gigabytes per second at various Electrum servers to make them inaccessible using a botnet of more than 140,000 machines.

Electrum has issued a new version of its wallet software, noting that older versions are most at risk because they’re most likely to connect to malicious servers.

“Updated versions are not at risk but the service might be temporarily unavailable,” Electrum creator Thomas Voegtlin told The Next Web. “If that is the case, we recommend to users that they stick to the same server (disable auto-connect) until they eventually manage to open a session.”

Electrum users are being advised to make sure they’re running the latest version of the software and download it only from the official electrum.org webste.

When Electrum was last attacked in December, the news spooked bitcoin markets, but that doesn’t appear to be the case today. Although not trading at the same highs it hit Sunday, bitcoin only dropped by 1% over the last 24 hours, to $5,229.31 as of 9:50 p.m. EDT, still near its highest levels for the year.

Image: Helperdz/Wikimedia Commons