BNB Chain isback in operationas of 07:00 Coordinated Universal Time (UTC) after it was forced to hit the brakes on Thursday after the blockchain with ties to the world's largest crypto exchange suffered what it called a "potential exploit" that on-chain evidence suggested could have targeted hundreds of millions of dollars in crypto.

BNB Chain is composed of BNB Beacon Chain and BNB Smart Chain (BSC).

"Due to irregular activity we're temporarily pausing BSC," BNB Chain tweeted from its official account, later confirming that the activity was a "potential exploit," that it characterized as contained.

Initial token movements suggested that up to two million BSC tokens were targeted by an attacker late Thursday, but the true losses may be much lower. BNB Chain estimated $100 million to $110 million in assets were moved off chain, but said in a tweet that $7 million was already frozen.

That such a small (comparatively speaking) sum of assets were stolen underscored the upside of BNB's gamble to halt the chain rather than risk more assets escaping. Blockchains are purportedly decentralized beasts designed to operate beyond the whim of singular entities: you aren't supposed to just flip an off switch.

BSCconfirmedthat it coordinated a shutdown of the chain after spotting issues with the BSC Token Hub protocol, the clearinghouse for crypto transactions moving between the Binance-linked blockchain's interlocking parts. It thanked validators for moving quickly.

"We are humbled by the speed and collaboration from the community to freeze funds," one tweet read.

The specter of an attack rocked BSC's native BNB token, which after a sleepy day of trading dipped to $280.40 from $293.10, according to CoinMarketCap, which Binance owns.

On-chain data shows that this afternoon two massive withdrawals of 1 million BSC tokens from BSC token hub by an attacker that nabbed crypto assets with cross-chains swaps, bridges, and borrows. Regardless, BNB's Twitter promised "all funds are safe" and said it will "help freeze any transfers."

Twitter sleuths point out that Tether – the largest stablecoin provider – has blacklisted the offending address, suggesting that the firm suspects the movement of tokens was the result of an attack rather than something more benign.