Sebastian Fernandez

@Bitfinding Co-Founder. Ex-hacker. Mostly EVM these days. Previously at @Microsoft, @MarshallWace.

[Sebastian Fernandez @snfernandez]

Wrote a post about those cases when shared_ptr<T> doesn't use atomic operations for the reference count. Spoiler: it's only in GNU and I couldn't decide if it's secure or not.

https://t.co/w5eOt7OkcF

[Sebastian Fernandez @snfernandez]

@austingriffith Congrats!

[Sebastian Fernandez @snfernandez]

@Montyly @aave Congrats!

[Sebastian Fernandez @snfernandez]

@lain_calvo @crecimientoar Good luck on the next projects! ygmi

[Sebastian Fernandez @snfernandez]

Well, at least this new era brought as back the exploit hashes!

[Nebula Security @nebusecurity]

sha256(exp): 6acf8941edca574ad77616ca3849af891826657ff6312c0665b06b3fd7bf341e

[Sebastian Fernandez @snfernandez]

@abarmat A rocky road for regulators but promising. In the meantime, I guess some countries will start as "medical paradises" where using the customized drugs, implants, etc will be legal and people could go there for these treatments

[Sebastian Fernandez @snfernandez]

Today is the last day of @giveth QF! In addition my previous donations, I added some projects that I found interesting with diverse solutions for fuzzing, blind signing, education, ops and consensus

[Sebastian Fernandez @snfernandez]

@DecurityHQ @BitFinding Nicer than ours for sure!

[BitFinding @BitFinding]

It's great having @DecurityHQ securing the blockchain at the milliseconds game. Competition in this space is what will make the last line of defense stronger!

[thedao.fund @thedaofund]

An AI agent that monitors every block, hunting smart contract hacks would be great right? Well @BitFinding is building it, and it has rescued $1.3M and counting.

Learn more: https://t.co/yzckaUuZs3

Support: https://t.co/viroDhjw2u

[Sebastian Fernandez @snfernandez]

@banteg gpt-5.5-high + kyc?

[Sebastian Fernandez @snfernandez]

@CryptoCatVC @BitFinding So my new heuristic actually works

[BitFinding @BitFinding]

This is the kind of security crypto needs more of: technical, proven, and built for the whole ecosystem.
Today it is only rewarded through bounties. @Giveth lets the ecosystem fund it proactively.
With QF, even $10 can carry far more weight.
https://t.co/Lp9JGSq0Dj

[BitFinding @BitFinding]

Our whitehat bot fuzzes the blockchain on real time, detecting and intercepting exploits.
As an example, only during the Balancer attack, we secured >$1M in a single block.
We’re raising on @Giveth QF to scale our public-good infrastructure.

[BitFinding @BitFinding]

🚨 Exploit Alert:

Bad error handling attack
Chain: Ethereum
Loss: 17 WBTC ($1.3M)

TX: 0x770bc9a1f7c32cb63a5002b9ceb5c7994cd3af0fc6b2309cb32d3c46f629daa0
https://t.co/UP0JiQFKcY

[Raz0r @theRaz0r]

Apart from my project Defimon, i've donated my boosted FINN tokens (as a ETHSecurity Badge holder) to the following awesome teams and products participating in the Ethereum Security QF round on @Giveth:
- Safe Multisig Transaction Hashes by @pcaversaccio
- Blockthreat by @iphelix
- @_SEAL_Org Safe Harbor
- BitFinding by @snfernandez
- @l2beat
- Recon by @GalloDaSballo
- K Stack by @palinatolmach
- OWASP Smart Contract Security by @cyberboyIndia
- GregoAI by @0xriptide
- Blockscout by @barinov

Special thanks to @griffgreen for organising this great initiative and the smoothest app I've used (Giveth).

[Sebastian Fernandez @snfernandez]

@theRaz0r @Giveth @pcaversaccio thank you for the support!

[shkz @shadkz_]

After years on #HackTheBox, I reached the top ranks and wrote a short, humble reflection on what changed along the way, including how #AI is shaping how we learn.

https://t.co/6N9BBIL6WX

[Sebastian Fernandez @snfernandez]

It's a honor!

[thedao.fund @thedaofund]

The next 60 ETHSecurity Badge holders have been selected using a new rubric updated by the applicants themselves!

Thank you to the people who chatted with the bot, your refinement of the rubric is the first DAO experiment we have tested.

And thank you to @bonfiresai for making amazing DAO tooling!

[Sebastian Fernandez @snfernandez]

It's not only frontrunning and backrunning but also siderunning