On November 3, 2025, Balancer, an Ethereum-based decentralized exchange (DEX), was exploited and an estimated $128 million worth of digital assets was stolen.
The incident is one of the biggest hacks of decentralized finance (DeFi) platforms this year. Worst balancer ever. This attack may have affected some of the liquidity deposited at the exchange.
From X’s account, the DEX team confirmed the attack.
We are aware of a potential exploit affecting Balancer V2 pools. Our engineering and security teams are conducting the investigation as a top priority. We will share verified updates and next steps as more information becomes available.
balancer team.
In these DEXs, the “pool” is a smart contract. Pool users’ funds Facilitates the exchange of tokens without intermediaries.
The fact that the exploit affected these pools means that a malicious attacker may have discovered a vulnerability in the contract code. allow its functionality to be changed Regular assets and withdrawn assets.
The leaked funds include wrapped versions of Ether, according to data from security firm PeckShield.
- 6,587 WETH ($24.4 million).
- 6,851 osETH (approximately $27 million).
- 4,260 wstETH ($19.3 million).
- Stablecoins and over 60,000 ERC-20 standard tokens.
Initial estimates by on-chain analytics firm Nansen, in collaboration with crypto trader Ted Pillows, put the stolen value at $116 million.
However, over time, this number was updated to 120 million, according to data from the BlockSec Phalcon monitoring platform. Increases commitment to $128 million.
Similarly, Dori assured that the attack spread through various chains of the Ethereum ecosystem. Among them are Capacity bases such as Ethereum, Arbitrum, Base, Polygon, etc.
Meanwhile, as reported by CriptoNoticias, the price of BAL, the DEX’s native token, Collapsed after balancer hacking.
How was the attack on Balancer, an Ethereum-based DEX, carried out?
According to researchers’ analysis On-chain known as AdiFlips in X,attack headed to vault (vault) and liquidity pool Balancer version 2 (V2).
In this protocol, vault These are smart contracts that store the funds of all pools and coordinate exchange operations between pools.
During pool creation or initialization, these contracts perform a series of “calls” that communicate orders between various components of the system (for example, registering new assets or setting liquidity parameters).
An attacker could have deployed a malicious contract such as: intercepted and manipulated those calls Manage changes to expected behavior during the configuration process. vault.
The reason for the failure is as follows How the protocol handled permission to interact between contracts An automatic feature calledcallback” (callback). This allows one contract to respond or perform a task when it calls another contract.
By exploiting a weakness in this mechanism, an attacker could cause the contract to perform unauthorized operations, such as swapping or transferring tokens, without proper validation.
This allowed him to Move funds cascadingly and rapidly between poolseject some of the stored assets before the system or validator reacts.
Analyst investigates Valencer hack: AI may have helped
In addition to this vulnerability in permissions and automated functionality, analysts detected clues that help them better understand how the attack was carried out.
Hours after the initial attack, AdiFlips noted that the malicious code included console logs (console.log) visible on the network. Something unusual happens in advanced attacks.
loss console.log is a snippet of code that developers use to display explanatory messages (such as “Step 1 completed”) and track how the program is performing during testing.
However, these logs will be removed before the final code is released. Therefore, the fact that they appear in actual transactions suggests that: Attackers may have used artificial intelligence (AI) tools According to AdiFlips, it’s also possible that you directly copied the code generated by one of them.
Meanwhile, another analyst pointed out flaws in the functionality. “Managing user balance” Balancer Protocol’s “Management of User Balances”).
According to the analysis, the balancer system I made a mistake when comparing two important parameters.
on the one hand, message senderidentifies the address that actually performs the actions in the contract. on the other hand, above. transmitterdata that can be manually established by the users themselves.
This confusion in validation allows any address to impersonate another address and perform an internal withdrawal operation (known as WITHDRAW_INTERNAL), i.e. the movement of funds within the protocol itself, without corresponding permissions.
Both observations strengthen the hypothesis that the attacks were attacked.Combining permission validation failures with improvised or AI-assisted codeThis facilitated the outflow of funds from the affected vaults.
