Many Web3 newcomers think that if a transaction simulator shows "0 loss", the approval is safe. This idea is very dangerous—the simulation only tells you "this signature won't immediately transfer your money", but it cannot see what that approval can do later. In July 2026, a user signed an approval that looked harmless, only to have 999,999 USDT stolen—nearly 1 million dollars. A simulation showing zero loss does not mean your assets are secure.
Step 1: Understand what a transaction simulation can and cannot tell you
[What to do] Figure out what the simulator's results cover and what they miss.
[How to do it] Any transaction simulation tool (built into wallets or browser extensions) works by pre-executing the transaction you're signing based on your current on-chain state, to judge whether it will cause immediate asset changes. It can:
Detect if the current signature directly transfers assets (like directly moving ETH or USDT)
Check if permission changes are immediately used in the current transaction
But it cannot:
Predict that this approval will be called three months later
Detect if a malicious contract is monitoring your balance, waiting for a large amount before acting
Tell you whether the approval amount is unlimited (
type(uint256).max), rather than just enough for one transaction
[Completion standard] You can clearly distinguish between "this current transaction has no loss" and "there will be no loss after the approval"—they are two different things.
Common failure reason: In a delayed execution attack in August 2025, a victim signed an unlimited USDC approval in April 2024, when the wallet balance was very low and the simulation showed no issue. 458 days later, after depositing $900,000 into that wallet, the attacker immediately called the prior approval and emptied it. This "get permission first, wait for the right time" tactic caused $723 million in approval phishing losses in 2025.
High risk: Attackers are using AI to automatically scan old on-chain approvals. Dormant approvals and abandoned contracts that used to require manual investigation are now being identified in bulk by automated tools. Every DApp you approved over the past few years could become a target. New protocols like EIP-7702 are also exploited: after a user signs an "authorization" transaction, the wallet's batch execution rights are temporarily delegated to the attacker, who can later trigger asset theft multiple times via bundlers without needing the user's signature again.
Step 2: Verify the real approval amount—don't trust what the frontend displays
[What to do] Don't just check the approval amount in the wallet pop-up; look on-chain.
[How to do it] Use specialized approval checking tools to examine your actual approvals:
Open Revoke.cash, connect your wallet, and view all token approval amounts and who they are approved to
Check if the amount is
unlimitedoruint256.max— if so, the approved party can transfer your entire balance of that token at any timeCheck if the approved address is a known DApp contract (e.g., Uniswap, 1inch) or some unknown address
[Completion standard] You can list all high-risk approvals in your wallet: unlimited amounts, unclear approval targets, very old approvals.
Step 3: Revoke unnecessary approvals to block delayed attack paths
[What to do] Clean up idle or high-risk approvals in your wallet.
[How to do it] Prioritize:
Top priority: Revoke all "unlimited" approvals that are older than 3 months
Second priority: Revoke approvals where the target contract address is unfamiliar
Daily habit: Get into the practice of "revoke after use" — after trying a low-frequency DApp, revoke the approval right away
Use Revoke.cash or a block explorer's approval management function to revoke. Revocation requires gas fees, but this is proactive defense—much more useful than contacting customer support after being hacked.
[Completion standard] All high-risk approvals have been revoked; your wallet's approval list only contains DApps you still actively use.
Verification after completion: After revoking, go back to Revoke.cash and refresh the list to confirm the target approval record has disappeared. For large assets (over $10,000), it's recommended to use a hardware wallet and disconnect your wallet after each DApp interaction. Build a regular check habit—once a month, scan your wallet with an approval management tool and clear out unused approvals.
