Heifereum Research Desk
A hacker does not always need your seed phrase or private key.
Sometimes the owner still controls the key—but is tricked into using that key to authorize the theft themselves.
This is the basic logic behind wallet drainers, malicious approvals and signature phishing.
The Basic Attack
A normal crypto transaction works like this:
The private key never needs to leave the wallet.
A drainer changes what the owner is being asked to authorize:
Cryptography worked correctly.
The problem was that the owner authorized the wrong instruction.
Simply Connecting a Wallet Is Usually Not Enough
Connecting a wallet normally reveals information such as:
- Public wallet address
- Network being used
- Assets visible on-chain
It does not automatically give the website the private key.
The dangerous moment usually comes afterward when the site asks the user to:
- Approve a token
- Sign a message
- Sign structured transaction data
- Approve an NFT operator
- Confirm an actual transaction
Chainalysis describes crypto drainers as phishing tools that convince users to connect wallets and approve transaction requests that give attackers control over assets.
Method 1: Malicious Token Approvals
DeFi applications need permission to interact with tokens.
For example:
This is normal.
The danger comes when a malicious application receives excessive spending permission.
The victim may believe they are approving:
Claim reward
But the important part may actually be:
Allow this contract to spend my tokens.
If broad permission is granted, the attacker may later transfer those approved tokens without asking the victim to sign every individual transfer.
MetaMask warns that malicious approvals can give a bad dApp excessive token-spending permissions and potentially drain approved assets.
Important Limitation
An approval normally applies only to the assets and permissions covered by that approval.
It does not automatically reveal the seed phrase or give unlimited control over every blockchain account the user owns.
Method 2: Signature Phishing
This is more subtle.
Not everything a wallet asks you to sign looks like a normal transaction.
A website might display:
- Login
- Verify wallet
- Claim
- Mint
- Confirm ownership
- Sign to continue
The victim sees what appears to be an innocent signature request.
But some blockchain standards allow signed messages to represent meaningful authorization.
The attacker later submits that authorization on-chain.
The attacker still never learns the private key.
They receive something almost as useful for that specific action:
a valid cryptographic authorization produced by the victim.
Approval phishing remains an active fraud technique; Chainalysis described investigations in 2026 where victims were socially engineered into signing approvals that later enabled wallet draining.
Method 3: Blind Signing
Sometimes a wallet cannot translate a complicated smart-contract request into something readable.
Instead of:
Approve 5,000 USDC
for XYZ Protocol
the user may see complicated encoded data or a generic warning.
The user signs without properly understanding the instruction.
This is called blind signing.
Ledger compares the problem to signing a blank cheque: the cryptographic signature is genuine even though the person may not understand what they authorized.
Modern wallets increasingly use clear signing, where important information such as the asset, amount, recipient and requested action is translated into readable information before confirmation.
Method 4: Fake dApps and Websites
Hackers frequently clone legitimate websites.
The fake interface might advertise:
- Token airdrops
- NFT claims
- Staking rewards
- Account migrations
- Wallet verification
- New token launches
The victim connects their real wallet.
The website then presents a malicious request instead of the expected transaction.
The website does not necessarily need to steal the seed.
It only needs the victim to approve the wrong transaction.
Chainalysis documented wallet drainers masquerading as legitimate Web3 projects and spreading through compromised social-media accounts and community channels.
Method 5: Fake Wallet Apps
There are two different versions of this attack.
Fake Wallet + Seed Theft
A fake wallet application asks the user to import their existing seed phrase.
Once entered, the attacker obtains complete control.
This technically does involve stealing the seed phrase.
MetaMask specifically warns that cloned wallet software can be designed to capture recovery phrases and recommends obtaining wallet software only through verified official sources.
Fake App + Malicious Signing
Another fake application may never ask for the seed.
Instead, it interacts with the real wallet and generates misleading transaction requests.
The victim signs them using their legitimate wallet.
Again:
the key remains secure while the authorization is compromised.
Method 6: Compromised Browser Extensions or Frontends
A user could visit the correct website and still face danger if part of the software around it has been compromised.
Malicious software can potentially manipulate what the user sees, redirect interactions or present a malicious transaction as something legitimate.
This creates one of the most dangerous situations:
SCREEN SHOWS:
Transfer 10 ETH
to company wallet
ACTUAL AUTHORIZATION:
Different transaction
This is why verifying transaction information on an independent hardware-wallet screen can provide another security layer.
However, even a hardware wallet cannot protect someone who knowingly confirms a malicious instruction displayed correctly.
Real-World Example: Ledger Connect Kit
On December 14, 2023, attackers compromised Ledger's Connect Kit software distributed to some Web3 applications.
Malicious code was injected into affected dApps and attempted to trick users into signing wallet-draining transactions.
Ledger said the incident originated after a former employee fell victim to phishing that enabled unauthorized publishing of malicious Connect Kit versions.
The important lesson:
The victim did not necessarily visit an obviously fake website. A legitimate software dependency had been compromised.
Real-World Example: The $1.46 Billion Bybit Attack
A much larger version of the same principle appeared in the February 21, 2025 Bybit attack.
Bybit was moving funds from an Ethereum multisignature cold wallet.
Investigations concluded that a Safe developer machine had been compromised, allowing attackers to present a disguised malicious transaction to Bybit's signers.
The required signers produced valid signatures.
Those signatures ultimately authorized malicious changes that allowed approximately $1.46 billion in assets to be removed from the wallet.
The private keys did not need to be mathematically cracked.
The attackers attacked the transaction approval process around the keys.
How Big Is Wallet Phishing?
Scam Sniffer estimated that wallet-drainer phishing caused approximately $494 million in losses during 2024.
The important shift is that attackers increasingly target the layer between humans and cryptography:
What Can Be Stolen Without the Seed?
| Situation | Can Assets Be Lost? |
|---|---|
| Simply viewing a wallet address | No |
| Simply receiving a token | Normally no |
| Connecting to a website | Normally not by itself |
| Malicious token approval signed | Yes, approved tokens may be at risk |
| Malicious NFT approval signed | NFTs covered by the permission may be at risk |
| Malicious transaction signed | Yes |
| Dangerous authorization signature signed | Potentially yes |
| Fake wallet receives seed phrase | Entire wallet potentially compromised |
| Private key stolen by malware | Entire corresponding account compromised |
Why Hardware Wallets Still Matter
A hardware wallet keeps the private key away from the normal computer or phone environment.
But:
A hardware wallet protects the key. It cannot automatically protect the owner from intentionally signing the wrong transaction.
The strongest protection is when the device displays the real transaction details independently and the user verifies them before confirming.
How Users Reduce the Risk
- Verify the exact website before connecting.
- Treat unexpected airdrops and claims suspiciously.
- Read approval amounts carefully.
- Avoid unnecessary unlimited token approvals.
- Regularly review and remove old permissions.
- Keep large holdings separate from wallets used for experimental dApps.
- Verify recipient, asset and amount before signing.
- Avoid signing transactions that cannot be understood.
- Install wallet software only from verified official sources.
- Treat unsolicited support messages as suspicious.
- Use hardware-wallet verification for significant holdings.
WalletConnect also provides domain-verification systems designed to warn wallets when users may be connecting to suspicious or impersonated domains, although it explicitly notes that such detection cannot guarantee safety.
If a Malicious Approval Was Signed
The important distinction is:
Approval compromised
The private key may still be safe, but existing permissions should be reviewed and unnecessary malicious permissions revoked.
Seed or private key compromised
Revoking approvals is not enough.
The attacker possesses the actual credentials and can continue signing new transactions. Remaining assets should instead be migrated to a completely new wallet.
MetaMask similarly distinguishes malicious approvals from full recovery-phrase or private-key compromise.
Conclusion
Hackers do not always attack cryptography.
Often they attack what the owner believes they are signing.
The blockchain does not know that the owner was tricked.
It only sees a mathematically valid signature.
That is why one of crypto's biggest security problems is no longer simply:
“Who has the private key?”
It is also:
“What exactly did the private key authorize?”
