Once you know what is a DEX and how it settles a trade, the next practical question is wallet security: connecting your own wallet directly to smart contracts introduces a specific set of habits worth understanding — ones that simply don’t apply the same way to a centralized exchange account.
{{IMAGE:assets/images/sec-featured.webp}}
What a token approval actually grants
Before a DEX’s smart contract can swap a specific token out of your wallet, you have to explicitly approve it to do so. That approval is itself an on-chain transaction, and it can be scoped to an exact amount or left “unlimited” — a setting many wallet interfaces default to for convenience, since it means you won’t need to approve again for future trades of the same token. An approval stays active until you manually revoke it or the wallet reaches its approved limit; it does not expire just because you finished the trade you originally approved it for.
Why unlimited approvals are risky
An unlimited approval means the approved contract can move the entire balance of that token from your wallet at any point in the future, not just for the trade you had in mind when you approved it. If that contract is malicious from the start, or a legitimate contract is later compromised through a bug or an exploited admin key, an unlimited approval left in place is a standing liability — the contract doesn’t need a new signature from you to drain the token once it already has permission. This is exactly the DEX-specific risk that has no real equivalent on a centralized exchange, where the platform (not a smart contract you individually approved) controls custody.
{{IMAGE:assets/images/sec-approvals.webp}}
Spotting a fake DEX interface
Because deploying a token or a front-end that mimics a real DEX generally requires no listing review or permission, phishing sites designed to look identical to a legitimate DEX are a documented attack pattern. Typing a DEX’s URL directly into the browser, rather than clicking a link from a search ad, social media post, or unsolicited message, is a standard precaution — a fake interface can request the same kind of token approval a real one would, and a wallet has no way to distinguish “legitimate DEX” from “convincing copy” on its own.
A practical pre-trade checklist
- Type the URL directly rather than clicking a link from an ad, DM, or social post.
- Check what’s being approved before confirming — the specific token and the amount, not just clicking through.
- Prefer an exact-amount approval over an unlimited one when the interface offers the choice.
- Periodically review active approvals and revoke ones tied to contracts or trades you no longer use.
- Treat every wallet-connection request as a real decision, not a routine click — see how a DEX actually executes a trade for the mechanism these approvals plug into.
{{IMAGE:assets/images/sec-checklist.webp}}