LEAF token drained via fee-accounting skim

Executive summary 01

The transaction is a contract deployment (to = null) sent by EOA 0x1ef4…d3ab. The deployed contract borrows USDT via a Moolah flash loan and, inside the loan callback, repeatedly triggers a side effect in the LEAF token's transfer logic. Each trigger moves LEAF out of the token contract's own balance into the LEAF/USDT PancakeSwap pair. The attacker then unwinds the inflated pool position back into USDT, repays the loan, and keeps the surplus.

Net result: the attacker EOA gains 1,628.42 USDT having supplied no capital; the LEAF/USDT pair loses exactly that much USDT; and the LEAF token contract is drained of 2,011.6 LEAF of its held reserves. This is the signature of an economic exploit, not legitimate activity.

How the attack worked 02

1. 1

   Deploy & pre-approve

   The tx deploys attacker contract 0xc77D…3F66, which spawns a helper 0x70e3…17f7 and a sub-contract 0xa5e6…98d4, then grants unlimited USDT/LEAF approvals to the PancakeSwap router and the Moolah lender.

2. 2

   Flash-loan 26,200 USDT from Moolah

   rescue(26200e18, 12600e18, 200) → flashLoan(USDT, 26,200) on the Moolah proxy. Execution enters the onMoolahFlashLoan callback with the borrowed USDT in hand.

3. 3

   Seed the pool: swap + add liquidity

   Sends 12,600 USDT into the LEAF/USDT pair, swaps for ~10,238 LEAF, then addLiquidity of ~13,600 USDT + ~10,136 LEAF — establishing an LP position it controls.

4. 4

   200× zero-value transfers — the exploit

   Fires transferFrom(pair, helper, 0) on LEAF 200 times (the 200 arg to rescue). A transfer from the pair routes into _handleBuy → _distributeBonus(), which fires regardless of amount and flushes a fixed MIN_FEE_POOL (~10 LEAF) tranche of the contract's own balance to LDX bonus recipients — the pool chief among them. ~200 × 10 ≈ 2,011 LEAF, all for free.

5. 5

   Unwind & convert to USDT

   Removes liquidity (burn), sweeps the sub-contract, then swapExactTokensForTokensSupportingFeeOnTransferTokens dumps ~11,713 LEAF back into the now–LEAF-rich pair for USDT.

6. 6

   Repay loan, pocket the difference

   Repays the 26,200 USDT to Moolah and transfers the 1,628.42 USDT surplus to the attacker EOA.

Net value changes 03

The 2,011.60 LEAF lost by the token contract lands as +1,475.53 (pair) + 203.74 (burn) + 332.34 (fee wallet) — the fee/burn split its own transfer logic applies. USD is current CoinGecko spot, approximate for a historical block.

Root cause 04

// LEAFToken (verified, solc 0.8.34) — the unguarded side effect
function _handleBuy(address from, address to, uint256 amount) internal {
    _distributeBonus();              // fires even when amount == 0
    uint256 burnAmount  = amount / 100;    // 0 when amount == 0
    uint256 finalAmount = amount * 99 / 100;
    ...
}
function _distributeBonus() internal {
    if (feePool < MIN_FEE_POOL) return;    // ~10 LEAF per call...
    uint256 share = minLpAmount[user] * MIN_FEE_POOL / totalStaked;
    feePool -= share;
    super._transfer(address(this), user, share);  // contract's OWN LEAF out
}
// attacker loop: 200 × transferFrom(pair, helper, 0)  →  ~2,011 LEAF drained

Actors & contracts 05

References — same exploit class 06

• DARKNAVY — Fee Token Skim Exploit
• DARKNAVY — AM Burn Reserve Manipulation (Mar 2026, Moolah flash loan, ~$131K)
• DARKNAVY — MAIL token drain via Moolah flash-loan callback
• PancakeSwap Fee-on-Transfer Exploit — Post-Mortem