How to Answer Common Smart Contract Security Mistakes in Blockchain Auditor Interviews

Most smart contract security mistakes involve weak access control, reentrancy bugs, and missing input checks. Developers sometimes leave functions public or skip trusted libraries, which leads to overflows.

Logic errors happen when teams rush testing or skip code reviews. Even experienced devs miss risks with external calls, especially in DeFi projects. Recent hacks, like flash loan exploits, highlight these issues.

In interviews, show you understand both technical details and why audits, tools, and good documentation matter for blockchain security.

Hey Victor. Good question. In an interview, I'd move beyond the textbook OWASP list and focus your answer on the patterns causing the biggest financial losses right now. I'd group them like this:

Access Control: This is more than just a missing onlyOwner modifier. Talk about subtler issues, like improper initialization bugs or compromised admin keys, which were the root cause of the Radiant Capital hack. It shows you're thinking about the entire security lifecycle.

Business Logic Flaws: These are bugs unique to the protocol's design that automated tools often miss. Mentioning the Thala hack, where a simple input validation error in their custom logic was exploited, proves you can think adversarially about a project's core function.

Oracle Manipulation: So many projects get this wrong. The Polter Finance hack is a perfect, recent example of how flash loans can be used to manipulate prices and drain a protocol. It shows you understand the critical risks of third-party integrations.

Framing it this way proves you're actively analyzing the current threat landscape, not just reciting a list.

Given your experience with Slither, are you noticing any new vulnerability patterns on L2s that aren't well-documented yet?

Really insightful thread so far—love how we’re surfacing actual challenges from recent hacks rather than just abstract theory.

Building on the point about L2s and cross-chain risk, my own audits have shown that assumptions made for Ethereum mainnet (especially regarding transaction ordering and gas semantics) can easily break on optimistic rollups and zkEVMs.

One practical example: I’ve seen confusion over the differences in how state commitments are finalized, which has led to timing bugs and race conditions that wouldn’t show up on L1. It's also smart to watch for upgrades or permissioned upgraders—too many recent exploits (like July’s Multichain and the Polygon zkBridge incidents) stemmed from overlooked admin pathways. Curious to hear: for those using Slither or MythX, are there plugins or custom detectors you’ve written to catch these newer L2-specific risks, or is manual review still the gold standard? Let's keep the knowledge flow going—real-world details from auditors in the trenches make all the difference for folks prepping for interviews or active jobs.

Really insightful thread so far—love how we’re surfacing actual challenges from recent hacks rather than just abstract theory.

Building on the point about L2s and cross-chain risk, my own audits have shown that assumptions made for Ethereum mainnet (especially regarding transaction ordering and gas semantics) can easily break on optimistic rollups and zkEVMs.

One practical example: I’ve seen confusion over the differences in how state commitments are finalized, which has led to timing bugs and race conditions that wouldn’t show up on L1. It's also smart to watch for upgrades or permissioned upgraders—too many recent exploits (like July’s Multichain and the Polygon zkBridge incidents) stemmed from overlooked admin pathways. Curious to hear: for those using Slither or MythX, are there plugins or custom detectors you’ve written to catch these newer L2-specific risks, or is manual review still the gold standard? Let's keep the knowledge flow going—real-world details from auditors in the trenches make all the difference for folks prepping for interviews or active jobs.