ChainBleedv0.1 · open intel
← back to feed·ETHFLASHLOAN2020-10-26 · 5y ago
Incident · SLOWMIST

Harvest Finance

Flash loan attack
Estimated loss
$21.50M
VERDICT —UNRATED
Verdict pending. Auto-ingested incidents are reviewed before a public verdict is rendered.
▰ METHOD
FLASHLOAN
FLASHLOANBYTECODE CATCHABLEAI SCANNABLE
Root cause

Root-cause analysis not yet published. The incident description below contains all currently available signal — review the attack transaction directly for definitive forensics.

▰ PROOF OF CONCEPT
DEFIHACKLABS
src/test/2020-10/HarvestFinance_exp.sol
view forked test on github ↗

Reproducible Foundry test fork from SunWeb3Sec/DeFiHackLabs. Clone the repo, run forge test against the file path above, and replay the exploit against a mainnet fork at the historical block. Use for reproduction only — not for live targets.

Forensic narrative

Data on the chain shows that a large amount of funds in the Harvest Finance fund pool were transferred, and about 24 million US dollars (Specifically, approximately USD 34 million)were successfully cashed out through multiple contract transactions, most of which were cashed out through renBTC. The initial ETH source used by the hacker this time was the Ethereum anonymous transfer platform Tornado.cash. The Hash for this operation is: 0x35f8d2f572fceaac9288e5d462117850ef2694786992a8c3f6d02612277b0877. It can be seen from the Ethereum browser that the hacker transferred 20 WETH to the Harvest Finance contract (address: 0xc6028a9fa486f52efd2b95b949ac630d287ce0af), and finally transferred the 20 ETH back to his address. Harvest Finance updated its Twitter saying that, like other arbitrage economic attacks, this time it originated from a huge flash loan and manipulated the price of one currency Lego (Curve y Pool) many times to deplete another currency Lego (fUSDT, fUSDC) Of funds. The attacker then converted the funds into renBTC and cashed out. Like other lightning loan attacks, the attacker did not give a response time, and attacked end-to-end for 7 minutes. The attacker returned $2,478,549.94 to Deployer in the form of USDT and USDC. On December 7, Harvest Finance officially announced the launch of GRAIN, USDC and USDT claim portals. Officials said that according to the previous hacker's refund of $2.5 million in funds, this reduced user losses to 13.5%. Officials are using USDC, USDT, and GRAIN tokens for mixed compensation to help users who were previously affected by the attack to make claims. Users will receive GRAIN tokens in proportion to their deposits, and the $2.5 million returned by hackers will be distributed proportionally. Attack method (per SlowMist): Flash loan attack. Reported loss: $ 21,500,000.

Primary source
https://www.zdnet.com/article/hacker-steals-24-million-from-cryptocurrency-service-harvest-finance/
Sourced from
slowmist
Technical record
chain
ethereum
protocol
Harvest Finance
bug_class
flashloan
date_occurred
2020-10-26
loss_usd
$21,500,000
source_id
sm:harvest-finance::2020-10-26
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