Swan Treasury loses $625K after signer key leak enables discounted STY purchases

Blockchain asset management protocol Swan Treasury has suffered an estimated $625,000 loss after attackers exploited a leaked off-chain signer key to buy STY tokens at a steep discount before selling them for profit. Summary Swan Treasury lost about $625,000 after attackers exploited a compromised off chain signer key on BNB Chain. The attacker bought about 687,000 STY at a 100 times discount using forged signatures and a PancakeSwap flash loan. Forged claim and transfer signatures allowed the attacker to sell the tokens into the STY USDT pool for profit. Security analysis found the transactions were signed with the protocol’s compromised signer key rather than exploiting a flaw in signature verification. According to blockchain security firm Defimon Alerts, the exploit took place on BNB Chain after the protocol’s off-chain signer key, hardcoded as the _signer address in the ZhaiquanBuy contract, was compromised. 🚨 @SwanTreasurpaj – Loss ~$625K (2026-07-30)Token: $STY @ $2.87Network: BNB ChainType: Private Key Compromise (signer key leak)The protocol's off-chain signer key (0xdEb4…8284, hardcoded as _signer in ZhaiquanBuy) was compromised. buy() sells STY at a signed discount:…— De...