A user installs the Keplr wallet extension, connects to Osmosis to manage liquidity, and approves what appears to be a straightforward swap transaction. The interface shows a readable preview, so the user assumes the contract interaction is transparent and safe. But behind that approval lies a critical vulnerability unique to many Cosmos-based blockchains: blind signing. The wallet cannot display what the smart contract will actually do because the blockchain does not provide human-readable transaction details in the way Ethereum and other networks do. The user has no way to know whether they are authorizing a token transfer or granting unlimited spend permission to an untrusted protocol.

This distinction is not theoretical. Users who approve transactions without understanding their full scope have lost funds to hidden contract exploits, permission escalations, and unexpected token drains. The Keplr wallet extension is one of the most widely used non-custodial applications in the Cosmos ecosystem, and its security depends entirely on whether users can verify what they are signing. Understanding blind signing, recognizing which chains enforce readable transactions, and adopting verification practices before approval are the only practical defenses.

What blind signing actually means on Cosmos blockchains

Blind signing occurs when a wallet asks a user to approve a transaction but cannot decode and display the contract actions embedded within it. On Ethereum, a wallet can often parse the ABI (Application Binary Interface) of a smart contract and show the user exactly what function is being called, which arguments are being passed, and what permissions are being granted. The user sees “Approve unlimited spending” or “Transfer 100 USDC to address 0x…” in readable language. That readability is not guaranteed—obfuscated contracts exist on Ethereum too—but it is the default assumption.

The Cosmos ecosystem uses a different transaction model. Many Cosmos chains encode contract messages in a format that the Keplr wallet extension cannot automatically decode without additional on-chain metadata. When a user connects to Osmosis, Juno, or other IBC-enabled chains and interacts with a smart contract, the wallet receives a serialized message. If the contract’s ABI or message schema is not registered with the wallet, the extension displays only a hexadecimal or base64 string, or a generic “contract interaction” warning, rather than the human-readable function name and parameters.

The security implication is direct: users approve transactions they cannot verify. This is why a malicious contract or a compromised DeFi interface could ask a user to sign what appears to be a harmless token swap, but the actual message grants unlimited token approval to a drainer contract, transfers NFTs, or delegates voting power. The user has no visual warning because the wallet cannot read the contract action in the first place. The signature they provide is cryptographically valid and irreversible; the blockchain will execute whatever the contract says it should.

Some wallet providers have attempted to mitigate this risk by implementing contract indexing or known-safe contract databases. The idea is to pre-register common contract ABIs so that frequent, legitimate contracts can be decoded and displayed. However, this approach has two critical weaknesses. First, it only helps for whitelisted contracts; any new, uncommon, or malicious contract remains opaque. Second, it creates a false sense of security by implying that registered contracts are inherently trustworthy, when the real security question is whether the user understands what they are authorizing.

How the Keplr wallet extension handles transaction visibility across different chains

The Keplr wallet extension experience is not uniform across all supported blockchains. Cosmos Hub, the original Cosmos chain, uses primarily bank transactions and stake delegation, which the extension handles well. A user can see “Delegate 10 ATOM to validator X” because bank transfers and staking operations have standardized, readable schemas. The wallet can parse these common operations and display them legibly.

The problems emerge on chains like Juno, Osmosis, and other CosmWasm-enabled networks that support arbitrary smart contracts. CosmWasm is Cosmos’s smart contract platform, and it allows developers to write contracts in Rust and deploy them on-chain. When a user interacts with a CosmWasm contract through an application interface, the wallet extension must somehow present the contract’s execute message to the user. If the contract’s schema is not already known to the Keplr wallet extension, the user sees only an encoded message—for example, `{“swap”:{“routes”:[…]}}` as raw bytes, with no guarantee that the wallet can interpret it correctly.

A user can mitigate this by manually checking the contract address on a block explorer, inspecting the contract’s source code (if it is open-source), and verifying that the application interface they are using is official. However, this burden is substantial. Most users do not have the time or expertise to review smart contract code, and many contracts are not open-source. The realistic security model is that if a user cannot read the transaction preview in the wallet, they should decline to sign unless they have independently verified the contract and the DeFi protocol through other means—such as checking announcements from trusted sources, reviewing the protocol’s documentation, or confirming the contract address through multiple independent sources.

Which Cosmos chains enforce readable transactions and which do not

Not all blockchains in the Cosmos ecosystem have blind signing problems equally. Cosmos Hub itself is relatively safe because most transactions are standard bank transfers, delegation, or undelegation operations. These fall into well-defined schemas that the Keplr wallet extension can read and display. A user delegating ATOM to a validator sees a clear message: “Delegate 10 ATOM to cosmosvaloper1xyz…” with no ambiguity.

Osmosis, one of the largest DeFi platforms on Cosmos, presents a mixed picture. Simple swap operations through the standard interface are often readable because Osmosis routes them through bank messages and documented contract patterns. However, more complex interactions—such as custom liquidity pool interactions, governance votes on complex proposals, or interactions with external CosmWasm contracts—can still be opaque. A user accessing Osmosis through its official interface and performing standard swaps may avoid blind signing; a user interacting with a custom contract address or executing complex routes may not.

Secret Network, by design, encrypts contract details on-chain, which means that even the network itself cannot immediately reveal what a contract does. This creates a deliberate trade-off: privacy is enhanced, but users have even less ability to verify contract interactions before signing. Evmos, which bridges Ethereum-style smart contracts to Cosmos, offers better transaction readability for EVM contracts but still depends on whether the Keplr wallet extension has the necessary ABI data.

Juno and other pure CosmWasm platforms remain high-risk for blind signing. Because contracts are arbitrary and numerous, the Keplr wallet extension cannot realistically pre-register every contract ABI. Users on these chains should approach new or unfamiliar contract interactions with particular caution, verifying the contract address through multiple independent sources and testing with small amounts before approving larger transactions.

The practical attack vectors enabled by blind signing

The most common attack begins with a compromised or malicious DeFi application. A user visits a website that claims to offer a token swap or liquidity farming opportunity. The interface is visually professional and may even mimic a legitimate platform. When the user clicks “approve,” the application requests a signature from the Keplr wallet extension, but the actual encoded message grants unlimited spend permission to an attacker-controlled contract. The user sees only “Contract Interaction” or a hexadecimal string in the wallet, because the wallet cannot decode the real message. The user approves, and the attacker drains their tokens over time or immediately transfers all approved assets to a burn address.

A second vector exploits social engineering combined with wallet limitations. An attacker creates a contract that executes a seemingly legitimate action—such as claiming a reward or participating in a governance vote—but embeds a secondary payload that drains approved tokens. If the primary action is common enough that the Keplr wallet extension has indexed it, the user may see a partial, misleading preview: “Claim Rewards” appears trustworthy, while the token drain happens silently in the background. The contract code is publicly visible on-chain, but users rarely inspect bytecode before signing.

A third vector targets NFT holders. A user approves what they believe is a safe NFT listing or auction transaction. The blind-signed message actually transfers their NFT to an attacker address or grants approval for unlimited NFT movement. Because many users do not expect NFTs to be at risk in the same way that token approvals are, the attack is particularly effective when combined with visually convincing interfaces.

Each of these attacks exploits the same fundamental vulnerability: the gap between what the user intends to authorize and what the blockchain actually executes. Blind signing makes that gap invisible. The Keplr wallet extension, in its role as a blockchain wallet, cannot close that gap alone; it can only be narrowed through user awareness and verification practices.

Best practices for reviewing transactions before approval

The first and simplest practice is to verify the contract address independently. If you are accessing a DeFi protocol, check the contract address in three places: the official documentation or website (using HTTPS and confirming the domain), a trusted block explorer, and a community resource such as a governance forum or discord channel moderated by the protocol team. If the contract address in the wallet matches all three sources, that is a necessary condition for safety, though not a sufficient one.

The second practice is to use a block explorer to inspect the contract code before signing. Services such as Juno Scan or Osmosis Explorer allow you to view the contract’s bytecode and sometimes its source code if it is verified. Reading Rust code is not practical for all users, but you can check whether the contract is open-source, whether it has been audited, and whether the source matches the on-chain bytecode. This step is particularly important for new or lesser-known protocols.

The third practice is to test with small amounts. If you are interacting with a new contract, send a small sum first, verify that the transaction executed as intended, and only then approve larger transactions. This approach reduces the damage from a misunderstanding or an attack; even if the contract is malicious, the attacker learns your approval, not your entire balance.

Fourth, adopt wallet security habits that reduce the window for attacks. Enable biometric or PIN authentication on your Keplr wallet extension so that signing requires a second factor. If your device is compromised, this does not prevent the malware from watching your approval, but it does prevent unattended signing. Similarly, use hardware wallet integration with Ledger if you hold significant balances; signing on a hardware device adds another layer of verification and makes remote attacks substantially harder.

Fifth, be extremely skeptical of unsolicited opportunities. If you receive a message—via email, social media, Discord, or anywhere else—pointing you to a DeFi opportunity with urgency or guaranteed returns, treat it as hostile until proven otherwise. Legitimate protocols do not need to recruit users through unsolicited messages; they market through established channels and official announcements. The message or link is likely a phishing attempt designed to direct you to a counterfeit interface.

How to recognize and avoid blind-signing exploits in real time

Before you approve any transaction in the Keplr wallet extension, pause and ask yourself: “Can I read what this transaction does?” If the answer is no—if you see only hexadecimal, base64, or a generic “contract interaction” warning—do not proceed unless you have independently verified the contract address and reviewed its code or audit report. This is the hardest rule to follow because DeFi interfaces are designed for speed and low friction. Legitimate applications want you to transact quickly; malicious ones want you to transact without thinking.

A readable transaction in the Keplr wallet extension preview should include the contract name (or a known alias), the function being called, and the key parameters. For example, “Swap 100 OSMO for 95 ATOM on Osmosis” is readable. “Execute Contract” with no further details is not. If you see only the generic version, ask yourself why you cannot see the details. Has the contract ABI not been registered? Is the application interface using an unusual encoding? Are you on the right chain? When in doubt, cancel the transaction and verify independently.

Another signal is the approval amount. If the transaction is requesting unlimited approval (approval amount set to “infinity” or a number equivalent to the full supply of the token), be especially cautious. Unlimited approval is sometimes necessary for certain DeFi operations, but it also means the contract can drain your balance at any time in the future without asking your permission again. Some protocols do require unlimited approval; others accept capped approval. If you are unsure, check the protocol’s documentation or ask in an official community channel before signing.

Finally, recognize that even a secure crypto wallet like Keplr cannot protect you from blind signing if you do not engage with the security model. The wallet can secure your private keys, support hardware wallets, offer biometric authentication, and integrate with trusted chains; it cannot read a message that the blockchain itself has not provided in a readable format. Your responsibility as a user is to supply the judgment that the wallet cannot provide—the willingness to verify before signing and the caution to decline uncertain transactions.

Why full transparency is harder than it appears

One might wonder why Cosmos chains and wallets have not solved blind signing entirely. The answer involves technical trade-offs and ecosystem incentives. Standardizing contract message formats and ABIs across thousands of independent developers is slow. Each CosmWasm contract author can define their own message schema, and there is no universal registry that covers all of them. Maintaining a comprehensive ABI database would require either a centralized authority—which contradicts the decentralized philosophy of blockchain—or a decentralized system that is slow to update and difficult to verify.

Some wallet providers, including the Keplr wallet extension maintainers, have taken steps to improve readability. They maintain registries of known contract ABIs, prompt users to review transaction details, and provide warnings for uncommon contracts. However, these measures are palliatives, not solutions. A comprehensive fix would require changes to the Cosmos SDK itself or universal adoption of better message encoding standards—changes that take years to implement and require coordination across hundreds of independent projects.

In the interim, the burden falls on users. This is not ideal, and it is not how the technology was supposed to work, but it is the current reality. Users who engage with smart contracts on Cosmos chains must treat blind signing as a permanent risk and adjust their behavior accordingly. That means treating every contract interaction as potentially dangerous, verifying everything you reasonably can, and accepting that some protocols or opportunities may be inaccessible to you because you cannot verify them safely.

A practical security checklist before signing any contract interaction

Before you approve any smart contract interaction in the Keplr wallet extension, run through this checklist. First, confirm the blockchain and contract address. Use a trusted block explorer and cross-reference against the official project documentation. A single character wrong in a contract address can send your assets to an attacker. Second, check whether the transaction is readable in the wallet preview. If it is not, research why and decide whether you are comfortable proceeding based on independent verification. Third, verify the approval amount. Unlimited approvals should be rare and deliberate; capped approvals are safer.

Fourth, test with a small transaction if this is your first interaction with the contract. A small loss is infinitely better than learning after the fact that you approved a drainer. Fifth, confirm that the interface URL matches the official domain and uses HTTPS. Copy the address directly from the official website rather than following a link from an email or message. Sixth, check governance forums, official discords, or community resources to see whether other users are reporting issues or attacks related to this contract.

Seventh, if the transaction seems too good to be true—guaranteed returns, urgent opportunities, exclusive access—it almost certainly is. Scams exploit both technical gaps like blind signing and human psychology. Legitimate opportunities do not need to convince you through pressure or appeal to greed. Finally, if at any point you feel uncertain, do not sign. The cost of declining a legitimate transaction is zero; the cost of approving a malicious one is potentially your entire balance.