When a user connects their crypto wallet to a decentralized exchange, lending protocol, or yield farming application, they typically encounter a permission request. That request asks the wallet to approve a smart contract to spend tokens on the user’s behalf. The approval appears straightforward: confirm the transaction, receive a success message, and proceed. What most users do not see is that many approvals grant unlimited spending authority. A contract approved to transfer 100 tokens today might, through negligence or malicious code, transfer the entire balance tomorrow. Understanding how approvals work in Bybit Wallet and other non-custodial wallets is not optional for managing cryptocurrency security.
The core issue is that cryptocurrency security depends not only on protecting recovery phrases and private keys, but also on controlling what applications are permitted to do with those assets once authenticated. An approval is not a one-time transaction. It is a persistent permission that remains active on the blockchain until explicitly revoked, survives wallet restores, and can be exploited long after a user has forgotten making it. A DeFi wallet such as Bybit Wallet allows users to interact directly with smart contracts, see transaction previews, and manage approvals, but the wallet can only show what is being requested—it cannot prevent a contract from misbehaving if the user grants it excessive authority.
How token approvals work on EVM-compatible networks
Ethereum and EVM-compatible networks such as Polygon use the ERC-20 standard to define how tokens transfer between addresses. An ERC-20 token contract stores a mapping of balances and a second mapping of approvals. When a user approves a contract, they are not sending tokens. They are updating that approval mapping to indicate that a specific contract (the “spender”) is allowed to transfer up to a certain amount on their behalf. The approval itself is a transaction that modifies the token contract’s state, consuming gas and appearing on the blockchain.
The critical detail is that approvals are not tied to a specific transaction or time window. Once set, an approval remains valid indefinitely unless the user submits a second approval to reduce the allowance to zero or change it to a different value. A contract that holds an approval can call the token’s transferFrom function at any point, taking tokens from the user’s address without asking for additional permission. That separation between the approval (a one-time user action) and the transfer (a repeated contract action) creates a persistent risk that most users do not intuitively grasp.
Bybit Wallet, like other non-custodial wallets supporting Ethereum and its ecosystem, presents approvals as part of the transaction confirmation flow. When a user connects to a DeFi protocol and initiates a swap or deposit, the wallet displays a preview showing what the contract is asking permission to do. If the contract requests an unlimited approval—often encoded as the maximum 256-bit integer—that detail should appear in the transaction preview. Many wallets, including Bybit Wallet, now warn users about unusually high or unlimited approvals, but the warning is only effective if the user reads it and understands the implication.
Unlimited versus limited approvals: The security trade-off
A decentralized exchange or other DeFi application faces a design choice. It can request a limited approval matching the exact amount the user wants to swap, or an unlimited approval that covers future transactions without requiring a separate approval step each time. Limited approvals are more secure: if a contract is exploited or behaves maliciously, the damage is capped. Unlimited approvals are more convenient: users do not need to approve again when making a second trade.
The asymmetry has shifted the industry toward more limited defaults, but unlimited approvals remain common. Some protocols still request them as standard practice, and many users accept them without reading the preview. A DeFi wallet user who approves an infinite spend allowance to a contract and later discovers that the contract has been exploited—whether through a bug, a protocol vulnerability, or compromised code—may watch their entire token balance disappear in a single transfer. Recovery is not automatic. The tokens are gone from their address, and the blockchain records the transaction as valid because the approval was legitimate, even if the contract’s use of it was not.
The practical recommendation is to request and grant limited approvals whenever possible. If a protocol does not allow specifying an exact amount and insists on unlimited approval, the user should approve only the amount they intend to spend in that session, not their entire holdings. Best practices outlined by security-focused organizations emphasize that users should approve the minimum necessary and regularly audit their approval history to revoke permissions they no longer need.
Cryptocurrency security through approval management in Bybit Wallet
Bybit Wallet provides transaction preview functionality that should display the approval amount before the user signs. The wallet also supports connection to hardware wallets such as Ledger and Trezor, which adds a physical confirmation step: the user must approve the transaction on the hardware device itself, creating a moment to reconsider whether the request is legitimate. That extra friction is intentional and valuable. A hardware wallet cannot prevent a user from approving a malicious contract, but it can slow the process enough for second thoughts.
The wallet’s support for multiple blockchain networks—Ethereum, BNB Chain, Optimism, Arbitrum, and Polygon—means that approvals exist separately on each network. An unlimited approval on Polygon does not affect Ethereum; the user must audit and manage each chain independently. For users managing significant token holdings across multiple chains, this creates a larger approval surface to monitor.
Revoking an approval is straightforward in technical terms but often overlooked in practice. On Etherscan, or a corresponding block explorer for other networks, a user can view all approvals associated with their address. Each approval is identified by the token contract, the spender contract, and the remaining allowance. Revoking involves submitting a new approval transaction setting the allowance to zero. This costs gas but is the only reliable way to remove permissions. No wallet feature, cloud backup, or recovery option can restore revoked permissions automatically because revocations are permanent blockchain state changes.
Users interested in reviewing approvals granted through Bybit Wallet can check the official contract documentation on the official Bybit Wallet site, which provides guidance on connecting to explorers and auditing transaction history. Some third-party approval management websites also allow users to view and revoke approvals in a batch, though this introduces a small trust assumption about the third-party interface itself.
Distinguishing between custodial and non-custodial approval risks
Bybit Wallet offers both custodial cloud-based key management and non-custodial seed phrase options. The distinction matters when considering approval risks. In a non-custodial setup, the user controls the private key and therefore authorizes all approvals directly. In a custodial arrangement, the wallet provider holds the key but the user still instructs the provider to sign approval transactions. In either case, once an approval is signed and broadcast to the blockchain, the user’s cryptocurrency security depends on the contract’s behavior and code quality, not on the wallet provider’s security posture.
The non-custodial option reduces one risk: the wallet provider cannot unilaterally approve contracts on the user’s behalf or use the private key for unauthorized purposes. It increases another risk: the user is entirely responsible for understanding what they are approving. A custodial wallet might theoretically detect and block a suspicious approval request, though most do not. The trade-off is control versus oversight, and for DeFi interactions, control is usually more important because DeFi protocols are designed around user-directed, non-custodial transactions.
For higher-value positions or less-frequent transactions, a hardware wallet like Ledger or Trezor paired with Bybit Wallet offers a middle ground. The hardware wallet holds the key and requires physical confirmation, but Bybit Wallet provides the interface for managing DeFi interactions. An approval transaction must be signed on the hardware device, which displays what is being approved. Most hardware wallets show the approval details clearly enough that a user can catch obviously malicious requests, though the decision to approve still rests with the user.
Recognizing and avoiding approval exploits
Approval exploits typically follow one of two patterns. The first is a contract that is genuinely useful initially but becomes compromised through an upgrade, maintenance key compromise, or developer negligence. A legitimate yield farming protocol might change its code or lose control of its upgrade mechanism, then use existing approvals to drain balances. These exploits are difficult to predict because they depend on future events and decisions by the protocol developers.
The second pattern is a fraudulent contract from the start—a token or DeFi application that appears legitimate but is designed to steal funds. Phishing remains a leading cause of cryptocurrency losses. A user might visit a lookalike website, connect their wallet, approve a contract, and discover too late that the contract was never legitimate. Wallet providers can reduce this risk through warnings about untrusted sites, but the burden ultimately falls on the user to verify URLs, check contract source code, and recognize social engineering.
Several defensive practices can reduce approval risk. First, verify that the contract address being approved matches the official website. Copy the address from a primary source, not from a search result or email. Second, check whether the contract code is open-source and has been audited. Ethereum Foundation resources and community tools document many common contracts; an unfamiliar contract address should be treated with suspicion. Third, use approval management tools or block explorers to periodically review active approvals and revoke those no longer needed. Fourth, when possible, use limited approvals and approve only for the amount being transacted in that session.
Regulatory context and best practices for cryptocurrency security
Cryptocurrency wallets and their users operate in an increasingly regulated environment. The UK Financial Conduct Authority and European Securities and Markets Authority have published guidance on cryptocurrency asset risks and custody considerations. While approvals themselves are not yet explicitly regulated, the principle that users should understand what permissions they grant is aligned with regulatory emphasis on consumer protection and informed consent. A wallet that clearly displays what is being approved and warns about unlimited allowances is closer to regulatory expectations than one that hides approval details.
For institutions and high-net-worth users, approval management becomes part of broader cryptocurrency security governance. Some organizations maintain approval policies limiting contracts to specific whitelisted protocols or requiring multi-signature authorization before DeFi interactions. Bybit Wallet’s support for hardware wallet integration can support these policies by requiring physical approval at the hardware device level.
Cryptocurrency security frameworks, such as those described by the National Institute of Standards and Technology, emphasize the principle of least privilege: granting the minimum access necessary to accomplish a task. Applied to token approvals, this means requesting limited amounts, revoking unnecessary permissions, and treating each approval as a potentially permanent grant of authority to be scrutinized carefully.
Implementing an approval audit and revocation workflow
A user holding assets across multiple chains and interacting with various DeFi protocols should develop a routine approval audit. Monthly or quarterly, visit a block explorer or approval management interface, view all active approvals, and identify those that are no longer necessary. This might include approvals to closed-down protocols, test transactions, or old DeFi positions. Each unnecessary approval is a potential attack surface that costs nothing to remove.
The actual revocation is a straightforward transaction on each network. Set the allowance to zero for any contract you no longer plan to use. Some approval managers batch revocations to save gas, but the principle is the same: submit a transaction, pay gas, confirm on the blockchain, and verify that the approval no longer appears in your balance. Bybit Wallet can facilitate these transactions just as it does DeFi interactions; the security benefit is purely the result of the user’s diligence in identifying and removing unnecessary permissions.
For tokens held in cold storage or moved infrequently, approvals may be less urgent to revoke because the account is rarely used. For active DeFi traders, the approval surface is larger and the audit cadence should be more frequent. Either way, the simple act of reviewing what permissions are active—and understanding that each one represents a potential drainage vector if a contract is exploited—is a foundational element of practical cryptocurrency security.
Frequently asked questions
What happens if I approve unlimited spending and the contract is exploited?
If a contract with an unlimited approval (or one approved for your entire balance) is exploited or behaves maliciously, it can transfer all approved tokens without additional permission. The transaction is recorded as valid on the blockchain because the approval was legitimate. There is no automatic recovery; the tokens are gone. This is why limiting approvals to the amount needed for a single transaction, or the nearest round figure above it, is a core practice in cryptocurrency security.
Can Bybit Wallet prevent me from approving a dangerous contract?
Bybit Wallet can display warnings about unlimited or unusually high approvals and allow you to review the contract address before confirming. It cannot determine whether a contract will behave maliciously in the future or whether the website you are visiting is legitimate. The wallet’s job is to show you what you are approving and facilitate the transaction you request; protecting yourself from phishing, exploited protocols, and fraudulent contracts is your responsibility as the account holder.
How do I revoke an approval I no longer need?
Visit a block explorer like Etherscan, search for your address, and view the “Token Approvals” section. Find the contract you want to revoke, click it, and approve a new transaction setting the allowance to zero. This costs a small amount of gas but is the only way to permanently remove permission for a contract to spend your tokens. Some third-party approval management tools can batch revocations to save gas, but the result is the same.