An unauthorized withdrawal of 3,998.5&nbsp;BTC (~$320&nbsp;million) from the Liquid Network, a bitcoin <button class="define-target" id="sidechain">sidechain</button>, prompted a network halt. By disabling nodes that <button class="define-target" id="bridge">bridge</button> between Liquid and the bitcoin mainchain, attackers are limited in their ability to cash out via bridge. Blockstream, the developers of Liquid Network, also said they had contacted exchanges to ask them to pause LBTC deposits and withdrawals, cutting off another avenue.<p>The unauthorized transaction included a message reading "we are <button class="define-target" id="whitehat">whitehats</button>. contact us on chain", suggesting the possibility that the withdrawal was in fact well-intentioned security researchers aiming to "rescue" funds after discovering they were vulnerable and then return them to a secure wallet. After some back and forth, the attacker returned 3,400&nbsp;BTC (~$272&nbsp;million) keeping 600&nbsp;BTC (~$48&nbsp;million), likely as a "<button class="define-target" id="bug-bounty">bounty</button>".</p>