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94. Security: Account Revival & Lamport Draining

Preventing zombie account vulnerabilities.

1 min read2 questionsup to 50 XPtopic 94/100

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If an account is closed and its lamports are drained to zero, another party can transfer 1 lamport to it within the same transaction to prevent the runtime from purging it, keeping its old data alive. Zeroing data explicitly mitigates this.

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Check your understanding

1. Why must smart contracts explicitly zero out account data when closing accounts?
To prevent an attacker from funding the account in the same tx to revive old dataTo save disk spaceTo pay validator feesTo reduce stack size
2. What does the Solana runtime do to 0-lamport accounts at the end of a transaction?
Purges and deletes them from stateKeeps them foreverFreezes themTransfers them to System Program

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