Smart Contract Exploit Analysis Flashcards
7 cards from real Blockchain Technology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Smart Contract Exploit Analysis flashcards as text
A function meant only for the owner that lacks an `onlyOwner` check is vulnerable to:
Answer: Unauthorized access / privilege escalation
Missing access control lets any caller invoke privileged functions like withdraw or upgrade.
The Parity multisig wallet freeze (2017) occurred because an attacker called which exposed function?
Answer: An uninitialized initWallet/library kill (selfdestruct) function
An unprotected initialization function let an attacker take ownership and selfdestruct the shared library, freezing wallets.
Using `tx.origin` for authorization is dangerous because:
Answer: A malicious intermediary contract can phish the original signer's authority
`tx.origin` reflects the original EOA, so a victim calling an attacker contract passes the auth check unintentionally.
In an upgradeable proxy, leaving the implementation contract's initializer callable can lead to:
Answer: An attacker initializing it and self-destructing or hijacking logic
An uninitialized implementation can be seized by anyone, who may then run delegatecall-based destruction.
A `delegatecall` to an attacker-controlled address is critical because the callee can:
Answer: Modify the caller's storage and context directly
`delegatecall` executes external code in the caller's storage context, allowing arbitrary state overwrites.
Which design reduces single-point access-control risk for sensitive admin actions?
Answer: A multisig or timelock-governed role
Multisig and timelock controls distribute authority and add delay, limiting damage from a compromised key.
Default function and state-variable visibility issues are mitigated by:
Answer: Explicitly declaring visibility (public/external/internal/private)
Explicit visibility prevents accidentally exposing functions or state that should be restricted.