Binance executives are racing to cover billions in losses from the biggest crypto heist in history, a breach that blew past everything the exchange had set aside to cover such an incident.

The hackers plundered $6.3 billion from the exchange's digital wallets by breaking into a Binance engineer's laptop, among other breaches, Binance said. Stablecoin issuers Tether and Circle, along with other crypto firms, managed to freeze about $3 billion of that sum, leaving roughly $3.3 billion under the hackers' control.

Binance has an emergency reserve called the Secure Asset Fund for Users, or SAFU, set up for cyber incidents like this. As of Thursday, the SAFU held $1.23 billion in bitcoin, blockchain data shows.

But the hack, attributed by cybersecurity researchers to North Korea's TraderTraitor hacking group, has rattled the overall crypto market, knocking bitcoin's price. This means the emergency fund is already $100 million lower.

Binance says it will fund the difference from its other company reserves. "Binance will cover all losses from the SAFU fund and company funds," co-Chief Executive Richard Teng said Friday on X.

The hack -- which the researchers say dwarfed any previous incident of its kind -- marks a black eye for Binance and the broader crypto industry. It led to a widespread discussion on social media and in crypto circles about whether Binance could cover the losses and how to make the industry safer -- including an online confrontation between Binance founder Changpeng Zhao and SpaceX CEO Elon Musk.

The hack "illustrates the risk concentration inherent in large, centralized intermediaries," Cristiano Ventricelli, a vice president at Moody's Ratings, said. "Stronger institutional controls can reduce some vulnerabilities, but the scale of assets under custody can amplify the impact of a successful breach."

Binance blocked customers from withdrawing funds while its team conducted security checks, saying Friday that withdrawal services should resume in two days. The exchange, which has a de facto base in the United Arab Emirates, says it doesn't accept U.S. customers. Its sister exchange, Binance.US, which operates in the U.S. and is separate from Binance, said it wasn't affected by the hack.

A Binance spokesman said the exchange has already reserved over $6.3 billion of company funds, including the SAFU amount, to cover users' affected assets. Of this sum, $5 billion is held in the same cryptocurrencies that hackers stole, the spokesman said.

Binance is purchasing the remaining $1.3 billion of cryptocurrency through market channels, the spokesman said, adding this step could take longer.

Binance holds its users' cryptocurrency on giant company-controlled digital wallets, known as hot wallets, which function as a ledger system recording which tokens are held by each customer on its platform. Once Binance replenishes its hot wallets with its own reserves, users' crypto holdings will be unchanged, Binance said.

"We will weather this storm," the spokesman said.

The loss, though severe, is small compared with the overall size of Binance's balance sheet. A total of $167 billion in crypto assets are held across its digital wallets, according to Nansen, a blockchain analytics firm. That sum includes user funds as well as Binance's own company assets and the SAFU reserve.

Binance also owns some assets that aren't reflected in such blockchain data.

Zhao, Binance's founder and majority owner, posted on Friday that the "remaining gap is (still painful, but) manageable."

Also on Friday, Musk posted a grimacing-face emoji in response to another X user's post of a screenshot of a tweet by jailed FTX founder Sam Bankman-Fried, whose crypto exchange collapsed in 2022.

Highlighting the strength of his financial position, Zhao, who is worth over $100 billion, replied to Musk that a stake Binance holds in SpaceX is valued at over $1 billion. Binance invested $500 million in X, then Twitter, back in 2022 as part of Musk's takeover of the company, which was acquired by SpaceX earlier this year. Zhao is Binance's biggest shareholder.

"Elon, have a lot of respect for you, but bad time to troll. Please stop," Zhao posted at Musk.

Also on X, Zhao discussed funding strategies with his romantic partner Yi He, who is Binance's other co-CEO.

Yi He, with whom Zhao has three children, posted at Zhao that Binance's annual revenue was sufficient to cover the losses. "We do not yet need to sell the SpaceX shares you are bullish on," she said, referring to Zhao. Binance last year processed $34 trillion in trades, on which it charges fees.

Zhao responded to Yi that he wasn't considering selling the SpaceX shares, but was flagging the holding for Musk "so that he can be less worried."