According to CoinMeta, with the emergence of a fourth wave of attacks on Bitcoin, the losses from cold wallets could approach $114 million. The attacks began on July 30th; the first wave resulted in the withdrawal of 1,083 Bitcoins from 1,196 addresses within 41 minutes. Subsequent attacks led to a total observed loss of 1,367 Bitcoins, involving 4,585 addresses. Researchers stated that attackers exploited Bitcoin's alternative fee feature, which allows unconfirmed transactions to be overwritten by subsequent transactions with higher fees. Cold wallet manufacturer Coinkite has released emergency firmware for each affected model and advised users to transfer their funds to newly generated addresses.