Blocked Platypus Attack: Industry's First Counter-Exploitation of a Hacker's Contract

Blocked Platypus Attack: Industry's First Counter-Exploitation of a Hacker's Contract

Since BlockSec’s debut in 2021, we have long maintained that code auditing alone cannot solve Web3 security issues. Therefore, we have been investing in exploring new paradigms for Web3 security. Thus we created Phalcon, the world's first crypto hack-blocking system.

Before the launch of Phalcon, the system had been running internally for 2 years, successfully blocking over 20 hacks, and rescuing more than 20 million USD worth of assets, including $3.8 million for Saddle Finance, $2.4 million for Platypus, $5 million for ParaSpace, and more.

In this series of articles, we will present representative successful stories of our system Phalcon. Today let's take a look at the industry's first counter-exploitation of a hacker's contract that rescued $2,400,000.

How We Blocked the Attack Against Platypus

On Feb 16, 2023, Platypus Finance suffered an attack and lost $9 million. Interestingly, the attacker made a huge mistake—they forgot to code the logic that would withdraw the funds from the attack contract. Fortunately, we found a way to leverage the attack contract to rescue $2M.

The attacker's contract has a function (flashloan's callback) that, when called, approves the transfer of USDC to the Platypus's contract. Although initially used for attack, now we can use it to approve the transfer of USDC from the attacker's contract to Platypus' contract.

Next, we wrote a PoC and verified that this rescue scheme works! We shared this solution with Platypusdefi and worked closely with them, successfully recovering $2.4 million USDC in this transaction.

BlockSec has always been at the forefront of crypto security. We work tirelessly to analyze and research every security incident and do everything we can to safeguard funds. Because we know that we're not just protecting numbers, we're protecting the lives of crypto users.

On July 12th, the Platypus faced another attack and the team responded quickly to minimize the damage. Immediate response is key! Yet, automated defenses like Phalcon can further minimize the damage.

How to Access the Service

  • Phalcon is a SaaS platform. You can log in to our website to explore features, view pricing, and subscribe directly.
  • You can also book a demo to learn more about Phalcon and receive expert security advice.

See More Success Stories of Phalcon

About Phalcon

Phalcon is an attack monitoring and automated blocking platform launched by BlockSec. The platform is capable of accurately identifying attacks and automatically blocking them. Phalcon aims to provide comprehensive post-launch security protection for Web3 projects, including continuous monitoring, attack blocking, and emergency response, safeguarding on-chain assets for protocol providers, LPs, and DAO organization participants.

To date, Phalcon has successfully blocked over 20 hacker attacks, rescuing more than $20 million in assets. Even in the early customer stage, Phalcon gained recognition and a grant from the top DeFi protocol Compound and established an attack-blocking platform for it.

Website: https://blocksec.com/phalcon

Twitter: @Phalcon_xyz

Telegram: https://t.me/BlockSecTeam

Sign up for the latest updates
#1 Cetus Incident: One Unchecked Shift Drains $223M in the Largest DeFi Hack of 2025

#1 Cetus Incident: One Unchecked Shift Drains $223M in the Largest DeFi Hack of 2025

Cetus Protocol, the largest concentrated-liquidity DEX on Sui, was exploited on May 22, 2025, resulting in an estimated ~$223M loss across multiple liquidity pools. The attacker leveraged a flaw in checked_shlw(), a custom overflow-prevention helper used in fixed-point u256 math, where an incorrect constant and comparison failed to block unsafe left shifts and caused silent truncation of high bits during liquidity delta calculations. By crafting specific liquidity and tick/price-range parameters, the exploit made required deposits appear near-zero while minting an oversized liquidity position, which was later withdrawn to drain real pool reserves.

#2 Bybit Incident: A Web2 Breach Enables the Largest Crypto Hack in History

#2 Bybit Incident: A Web2 Breach Enables the Largest Crypto Hack in History

The largest crypto hack ever, the February 21, 2025 Bybit breach stole about $1.5B after attackers used social engineering to compromise a Safe{Wallet} workflow, injected malicious JavaScript into an AWS S3 bucket, tampered with the transaction signing process, and upgraded Bybit’s Safe{Wallet} contract to a malicious implementation that drained funds across multiple chains.

Weekly Web3 Security Incident Roundup | Jan 25 – Feb 1, 2026

Weekly Web3 Security Incident Roundup | Jan 25 – Feb 1, 2026

During the week of January 25 to February 1, 2026, six blockchain security incidents were reported with total losses of ~$18.05M. These involved improper input validation, token design flaws, key compromises, and business logic errors across DeFi protocols on multiple chains. The primary causes included unchecked user inputs enabling arbitrary calls, flawed burn mechanisms allowing price manipulation, compromised developer tools, and missing solvency checks in lending functions.