Yearn Finance, TMXTribe, Prism Protocol: $10.5M Lost to Mispriced Pools, Over-Minting, and Role Misuse

In Brief

• TMXTribe lost $1.4M after due to a price manipulation exploit.
• Prism Protocol lost $62K after a malicious contract was approved as a manager and used token burns to manipulate price.
• Yearn Finance lost $9M after imbalanced deposits broke pool math and allowed over-minting.

Hacks Analysis

TMXTribe | Amount Lost: $1.4M

On January 6th, the TMXTribe exploit on Arbitrum resulted in a $1.4M loss. The root cause of the exploit was that TMXTribe's contract allowed minting, staking, and swaps without validating balances or enforcing constraints. The attacker minted and staked TMX LP tokens using USDT, then swapped the same USDT into the protocol's USDG stablecoin. The attacker then unstaked the LP tokens and sold the newly created USDG. The exploit was repeated continuously over 36 hours.

Exploited Contract (Arbitrum): 0x27037A167a60bc6ECdEdE086DdDC5D250263E76d

Transaction: 0x8817bf120718ff91e8c9792272f69a8ae7a573f4b5bf930deae79b008f70688a

Prism Protocol | Amount Lost: $62K

On December 11th, the Prism Protocol exploit on Binance Smart Chain resulted in a $62K loss. The root cause of the exploit was that a malicious contract was mistakenly approved as a SniperManager. This role assignment allowed the attacker to call the BurnSniperTokensBought() function and burn PRISM tokens. The attacker reduced the liquidity and artificially increased the PRISM token price, making a profit.

Exploited Contract (BSC): 0x1284c1f20a7f0322a5e17618f764f0d3cbaccee9

Transaction: 0x23879edbd3366cdc774aaa72a8484b7f7ef641f68f01345764bf44d812d042a6

Yearn Finance | Amount Lost: $9M

On November 30th, the Yearn Finance custom yETH pool exploit on Ethereum mainnet resulted in a $9M loss due to a logic vulnerability. The attacker made imbalanced deposits that pushed the pool's internal calculations outside their safe range. The attacker first called the add_liquidity() function and made imbalance deposits that pushed the pool's internal calculations outside their safe range. The pool computed a product term using vb_prod = (prev_vb / vb)^(weight). Because the deposits dwarfed existing balances, this value collapsed toward zero. This caused the pool to miscalculate its internal supply and over-mint yETH LP tokens. The attacker used the excess LP to repeatedly call remove_liquidity and drain LST assets.

Exploited Contract: 0xccd04073f4bdc4510927ea9ba350875c3c65bf81

Transaction: 0x53fe7ef190c34d810c50fb66f0fc65a1ceedc10309cf4b4013d64042a0331156

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