Every time you use tokens in a DApp, you usually need to give the DApp's smart contract an "Approval" first, allowing it to manipulate specific tokens in your wallet. This approval will persist forever, even after you stop using that DApp. If one day this DApp's contract is hacked or the project developers run away (rug pull), hackers can exploit the approval you previously gave to directly transfer tokens out of your wallet, and you might be completely unaware. This is why regularly checking and revoking no longer needed DApp approvals is one of the most important habits in Web3 wallet security management, similar to regularly checking if your bank card is tied to unknown auto-deduction services. Many people continuously grant approvals to various contracts during DeFi operations and forget about them after use, accumulating a massive amount of hidden security risks over time. Before proceeding, you need to have an account registered on the Binance official website and activated the Web3 Wallet, with the latest version of the Binance official APP installed on your phone to manage your on-chain approvals. If Apple phone users need to reinstall the APP, they can refer to the iOS installation guide. Below is a detailed explanation of the principles of approvals and how to revoke them.
Understanding the DApp Approval Mechanism
What is Token Approval?
When you use USDT to swap for other tokens on a decentralized exchange (like PancakeSwap) for the first time, PancakeSwap's smart contract cannot directly touch the USDT in your wallet. You must first execute an "Approval" transaction, telling the USDT contract: "Allow the PancakeSwap contract address to use the USDT in my wallet." This approval is recorded on the blockchain; afterward, PancakeSwap can automatically deduct USDT from your wallet to complete the swap when you confirm a transaction.
Approval Amounts
When granting an approval, a maximum limit is specified. There are two common modes:
- Exact Approval: Only approves the exact amount needed for the current transaction. For example, if you want to swap 100 USDT, you only approve 100 USDT. The next time you swap, you will need to approve again, costing an extra Gas fee but making it safer.
- Unlimited Approval: Approves a massive amount (usually 2^256-1, an astronomical number), essentially giving the DApp unlimited usage rights. This way, you don't need to re-approve for future transactions, saving Gas fees but carrying much higher risk.
Most DApps request unlimited approval by default because it offers a better user experience (fewer operational steps). But from a security perspective, an unlimited approval means that if the contract is compromised, attackers can transfer your tokens away without any amount restriction.
Duration of Approvals
Once a token approval is executed, it exists permanently on the blockchain and does not expire. Unless you actively revoke it, this approval will remain valid. This is why a DApp you used six months ago can still manipulate your tokens today if its contract remains authorized.
Viewing Existing Approvals
Viewing via Binance Web3 Wallet
The Binance Web3 Wallet might have a built-in approval management feature. Enter the "Security" or "Settings" page of the Web3 Wallet and look for "Approval Management" or "Token Approvals" options. If available, you can directly check which DApps you have given approvals to across various chains here.
Viewing via Third-Party Tools
If the Binance APP does not have a built-in approval management feature, you can use the following third-party tools by accessing them through the Binance Web3 Wallet's DApp browser:
- Revoke.cash: Supports multiple EVM chains, with a clean and intuitive interface.
- DeBank: Besides approval management, it also provides complete DeFi asset tracking.
- Etherscan Token Approval Checker: The official Ethereum block explorer's approval checker tool.
- BSCScan Token Approval Checker: The approval checker tool for the BSC chain.
Taking Revoke.cash as an example: Access revoke.cash in the DApp browser, connect your Web3 Wallet, and the website will scan all approval records for your address on the selected network and list them.
Information Included in the Approval List
When viewing approvals, you will see the following information:
- Approved Token: Which token you approved (e.g., USDT, WBNB, etc.).
- Approved Contract Address: Which smart contract you gave the approval to.
- Approved Amount: The maximum limit of the approval (if it shows a huge number or "Unlimited", it's an unlimited approval).
- Approval Time: When the approval was granted.
Steps to Revoke Approvals
Revoking via Revoke.cash
- Open revoke.cash in the DApp browser of the Binance Web3 Wallet.
- Connect your Web3 Wallet.
- Select the network you want to check (e.g., BSC, Ethereum, etc.).
- Wait for the scan to finish; the page will list all approvals.
- Find the approval you want to revoke, and click the "Revoke" button next to it.
- The wallet will pop up a transaction confirmation window; confirm it to pay the Gas fee.
- Once the transaction is confirmed, the approval is revoked.
Revoking via Block Explorers
Taking BSCScan as an example:
- Visit bscscan.com.
- Connect your wallet or enter your wallet address.
- Enter the Token Approvals page.
- Find the approval to revoke, and click "Revoke".
- Confirm the transaction and pay the Gas fee.
Gas Fees for Revoking Approvals
Revoking an approval is itself an on-chain transaction and requires paying a Gas fee. Revoking an approval on BSC costs roughly under $0.1, while on Ethereum it might cost a few dollars. If you have many approvals to revoke, the fees will add up. It is recommended to prioritize revoking high-risk approvals (large/unlimited approvals, approvals to unknown DApps), while low-risk ones can wait until Gas is cheap to handle.
Which Approvals Should Be Prioritized for Revocation
High Priority: Revoke Immediately
- Unrecognized Contract Addresses: If you don't remember giving an approval to a specific contract, or if the contract address looks suspicious, revoke it immediately.
- Rug-pulled or Hacked Projects: If a project you previously approved is exposed for having security issues or has stopped operating, revoke it immediately.
- Unlimited Approvals to Small Projects: Giving unlimited approvals to lesser-known, small projects is high-risk; it is recommended to revoke them.
- Unused DApp Approvals for a Long Time: Revoke approvals for DApps you haven't used in over three months.
Medium Priority: Revoke When Convenient
- Unlimited Approvals for Mainstream DApps: Top-tier projects like Uniswap and PancakeSwap are relatively safe, but it's still recommended to revoke unlimited approvals if you don't use them frequently.
- Discontinued but Known Projects: For example, well-known DeFi protocols you used before but no longer use.
Low Priority: Can Be Kept
- DApps You Are Actively Using: If you trade on PancakeSwap every day, keeping the approval saves the Gas fee of re-approving every time.
- Exact Amount Approvals: If the approved amount is very small (e.g., 100 USDT), even if an issue occurs, the loss is limited.
Preventive Security Measures
Choose Exact Amounts When Approving
When granting approvals to DApps, many wallets allow you to customize the approval amount. Do not blindly click to confirm unlimited approvals; manually enter the exact amount you need to use for the current transaction. Although you will need to re-approve next time, the security is greatly enhanced.
Use a Dedicated Interaction Wallet
If you frequently use various DApps, it is recommended to create a dedicated wallet address specifically for DApp interactions, keeping only a small amount of funds in it. Keep the bulk of your assets in another "vault" address that grants no external approvals. This way, even if the interaction wallet's approvals are exploited, the loss is contained.
Keep Up with Security News Promptly
Cryptocurrency security incidents happen frequently. Follow reliable security news sources (like SlowMist, PeckShield, etc.). If a project you have approved experiences a security issue, revoke the approval immediately.
Develop a Habit of Regular Cleanup
It is recommended to conduct an approval audit every two weeks to a month. Just like a regular health checkup, periodically cleaning up unnecessary approvals effectively lowers long-term risk. You can set a recurring reminder on your phone calendar.
Common Scams Related to Approvals
Malicious Approval Phishing
Scammers create a seemingly normal DApp, tricking you into connecting your wallet and approving tokens. The moment you grant approval, they immediately use the contract to transfer all your tokens away. Prevention: Do not use DApps of unknown origin, and do not click on suspicious links.
Fake Airdrop Scams
Your wallet might receive unknown tokens claiming to be an "airdrop". When you attempt to sell these tokens, you are redirected to a fake DEX and asked to approve your mainstream tokens. Once approved, your assets are stolen. Prevention: Ignore unknown tokens that suddenly appear in your wallet.
Approval Upgrade Scams
Some malicious contracts will upgrade their contract logic after you grant approval, turning a previously normal function into a coin-stealing function. This type of attack is advanced and difficult for average users to identify. Prevention: Only interact with well-known, audited projects, and avoid using unverified contracts.
Conclusion
DApp approval management is a critical aspect of Web3 wallet security, and the core principle boils down to three words: Regular Cleanup. Remember to check your approvals every time after using a DApp, and decisively revoke those you no longer use. Try to use exact amounts rather than unlimited approvals when authorizing. By maintaining this habit, your Web3 wallet can operate securely over the long term. Remember: In the blockchain world, security always comes first because on-chain losses are almost irreversible.