SwissBorg Solana Staking Exploited via Partner API Compromise → Security

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Briefing

SwissBorg’s SOL Earn staking program suffered a sophisticated exploit, resulting in the loss of approximately $41 million in Solana tokens. This incident stemmed from a critical vulnerability within a third-party partner’s API, enabling attackers to gain unauthorized control over stake account authorities. The breach underscores the severe cascading risks inherent in external dependencies within the DeFi ecosystem, leading to a substantial financial impact for the platform and its users. The total financial impact is quantified at $41 million in stolen SOL.

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Context

Prior to this incident, the broader DeFi landscape grappled with an expanding attack surface, particularly concerning the integration of external services and APIs. Protocols often rely on third-party infrastructure for specialized functions, introducing inherent supply chain risks. The prevailing challenge involves ensuring robust security across these interconnected systems, where a single point of failure in a partner’s API can expose a protocol’s on-chain assets.

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Analysis

The attack exploited a critical vulnerability within Kiln’s staking infrastructure API, SwissBorg’s third-party operator. Attackers leveraged unauthorized access to this API to manipulate stake account authorities, specifically the ‘Staker’ role, without triggering immediate anomaly detection. This manipulation allowed the silent transfer of withdrawal authority from SwissBorg/Kiln-managed stake accounts to the attacker’s wallet.

Subsequently, the attacker initiated unstaking and withdrawals, effectively draining 192,600 SOL from the SOL Earn program. This incident involved an off-chain API breach that exposed on-chain controls; the vulnerability did not originate from a smart contract flaw within SwissBorg’s own codebase.

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Parameters

Protocol Targeted → SwissBorg SOL Earn Program
Attack Vector → Third-Party API Compromise (Kiln’s staking API)
Financial Impact → $41 Million USD (192,600 SOL)
Blockchain Affected → Solana
Exploit Date → September 8, 2025
Vulnerability Type → Unauthorized Stake Account Authority Manipulation
Attacker Wallet → SwissBorg Exploiter (on Solscan)

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Outlook

Protocols must immediately reassess their third-party API integrations, implementing enhanced anomaly detection and multi-signature confirmations for critical operations. This incident signals a heightened contagion risk for other DeFi platforms relying on similar outsourced staking or yield infrastructure. The industry will likely establish new security best practices, emphasizing rigorous vetting, continuous monitoring, and penetration testing for all external dependencies to fortify the overall security posture.

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Verdict

This incident unequivocally demonstrates the critical need for comprehensive supply chain security, extending beyond smart contract audits to encompass all external API integrations within the digital asset ecosystem.

Signal Acquired from → quillaudits.com