2026-06-18 · tangem
Tangem published a security guide explaining how SIM swap attacks can move from a carrier support call to email and exchange account takeover. The post is directly tied to cold storage because Tangem argues that significant crypto holdings should be moved out of SMS-dependent exchange accounts and into self-custody hardware wallets.
Tangem explains that SIM swap attackers do not need malware if they can move a victim's phone number to a SIM they control. Once they receive SMS codes or password-reset messages, exchange accounts and email accounts protected by phone-number recovery can become exposed.
A SIM swap can convert a mobile-carrier failure into direct financial loss when funds are held on custodial exchanges. Tangem also notes that breached personal data can help attackers target crypto holders, making long-term exchange storage especially risky.
Hardware cold storage removes the phone number from the access path because signing requires physical possession of the wallet device or card. Tangem says its self-custody model stores private keys in a secure element and does not rely on SMS, email, cloud accounts, or service logins to approve transactions.
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