Recently, the security agency BlockSec Phalcon disclosed a cross-chain contract authorization attack incident, where two contract deployers were suspected to have been exploited, leading to a batch of user assets being instantly drained. According to their single-source statistics, the overall loss from this incident exceeded 17 million USD, with addresses related to Aperture Finance and SwapNet being the most affected. The attack spanned multiple public chains including Ethereum, Arbitrum, Base, and BSC. On the surface, this was a technical attack; fundamentally, it exposed how DeFi, in pursuit of "seamless authorization and ultimate experience," has pushed users onto a high-risk gambling table woven with unverified contracts and complex authorization designs—when you click "authorize" in a black box, what exactly are you giving away?

Authorization as an ATM Card: How Attackers Turned User Wallets into ATMs

● Opaque arbitrary calls: In this incident, the victim contract was not open-source and had arbitrary call capabilities, requiring users to grant operational permissions for certain tokens without being able to see the source code. For most ordinary users, they can only rely on project branding, reputation, or aggregator recommendations to judge "whether it is trustworthy," but they may not realize that an arbitrary call black box contract, once abused, equates to giving someone a "universal card" to withdraw your assets at any time.

● Blood-sucking path exploiting authorization vulnerabilities: According to BlockSec Phalcon's analysis, the attacker exploited design flaws in the authorization of such contracts to directly siphon assets from user addresses via the transferFrom path. On the surface, this appeared to be a normal token transfer, but since users had previously granted high limits or even unlimited authorization to the contract, the transferFrom call was "legitimate" on-chain, ultimately resulting in a technically compliant yet fatal "authorization equals withdrawal."

● Single-source portrait of loss structure: In the disclosed figures, addresses related to Aperture Finance lost approximately 3.67 million USD, and addresses related to SwapNet lost approximately 13.41 million USD, totaling nearly 17 million USD, which aligns closely with BlockSec's statement of "total losses exceeding 17 million USD." It is important to emphasize that these amounts come from a single security agency's statistics, and the complete list of victims and more detailed fund distribution have not yet been disclosed; what the outside world can currently see is just the tip of the iceberg.

● Token swaps and cross-chain transfers on Base: In terms of fund flow, the attacker exchanged approximately 10.5 million USDC for about 3,655 ETH on the Base chain, and then transferred it to Ethereum via a cross-chain bridge. This series of operations was extremely swift on-chain, leveraging Base's low cost and high efficiency, while also diluting tracking difficulty through cross-chain means, paving the way for further laundering or splitting.

The Black Box Gambling Table of Non-Open Source Contracts: Betting Trust Against Invisible Code

● Trust replacing audits: Non-open source contracts are not uncommon in DeFi, but this means users cannot independently or commission an auditor to fully review the code, and can only "hear" about key permissions, call boundaries, and upgrade mechanisms. In this model, users are not participating in a verifiable smart contract, but rather in a "I trust it won't scam me" trust contract, where branding, endorsements, and social media reviews are passively elevated to the core basis for security judgment.

● The lethal combination of arbitrary calls and broad authorization: The structural risk exposed in this incident is that—once a black box contract has arbitrary call capabilities and receives broad authorization from users, it effectively hands over the initiative of the wallet. Users may only want to complete a swap or strategy operation during interaction, but at the logical level, the contract has obtained the keys to delay, batch, or even cross-asset calls. Once this key falls into the hands of an attacker, the consequence is a concentrated and difficult-to-warn asset drain.

● Industry inertia prioritizing experience over security: The DeFi industry has long exhibited a path dependency—first achieving a "smooth and seamless" user experience, leaving security issues for later "upgrades" and "audits." Project teams often prioritize fewer signatures, fewer pop-ups, and larger default authorizations in competition, while users, caught between "peace of mind" and "thinking one step further," are naturally pushed towards convenience. The game between security and experience manifested in the most brutal way in this incident: when the experience is so good that you forget what you previously signed.

The Backlash of One-Time Authorization: Intended to Be More Conservative, Yet Falling into a Deeper Pit

● Authorization model and psychological gap: In various aggregators and trading services, "unlimited authorization" and "one-time authorization" are almost default options. The former seeks to reduce the hassle of frequent confirmations, while the latter is viewed by many users as a safer, "more controllable" choice. Once one-time authorization is turned off, users often develop a psychological belief: if I manually agree each time, it should be safer, yet they overlook who exactly they have granted permissions to and at what logical level.

● Counterintuitive victim group: In this incident, the security team pointed out that the main affected group was users who had turned off "one-time authorization," which is contrary to many people's security intuitions. The logic is that: seemingly more conservative settings, under certain implementations, can concentrate more operations on a "middle" contract that is trusted more, and once this middle layer has design flaws or is abused, it is precisely the users who consider themselves more cautious that are first affected, exposing the highly misleading risks in authorization design and implementation.

● Complexity highlighted by authorization revocation suggestions: After the incident was disclosed, some security teams called on users to revoke all aggregator authorizations except for the 0x one-time approval contract, equivalent to informing ordinary users: you may have unknowingly issued high-limit checks to multiple aggregators and intermediary contracts. For most people, checking one by one to identify which contracts are "necessary" and which are "excessive" is itself a highly challenging task, reflecting how unfriendly current authorization management is to ordinary users.

● Misalignment of security intuition: From the user's perspective, "confirming a few more times" and "limiting the scope of authorization" always sounds safer, but in a reality where hidden logic is complex and contract coupling is high, intuition often does not align with the actual risk distribution. This incident laid bare a harsh truth: when you do not understand the underlying call chain, so-called "conservative operations" may merely change direction, pushing you into a more concealed high-risk area.

The Failure of Four Public Chains: Amplifiers of Attack in the Multi-Chain Era

● Multi-chain collaboration amplifying attack space: According to BlockSec, this attack involved Ethereum, Arbitrum, Base, and BSC, with victim assets distributed across different ecosystems, allowing attackers to flexibly allocate based on cost, liquidity, and anonymity. For security teams and ordinary users, funds do not "stick" to a single chain but traverse across multiple chains, directly increasing the difficulty of identification, freezing, and tracking.

● Demonstrative effect of token swaps and cross-chain on Base: The attacker exchanged approximately 10.5 million USDC for about 3,655 ETH on the Base chain, then cross-chained to Ethereum, which is a typical multi-chain attack path: first utilizing a chain with lower costs and congestion to complete large exchanges, then migrating mainstream assets to a main chain with deep liquidity and diverse exit methods. This process is not technically complex, yet it amplifies both attack efficiency and money laundering space through multi-chain infrastructure.

● Boundaries of single-chain risk control: In a multi-chain ecosystem, the risk control capabilities of any single project or single chain are difficult to form a closed-loop blockage against cross-ecosystem attack paths. Even if a risk warning has been triggered on one chain, funds may have already been settled and split on another chain. What the industry needs is not just security plugins within chains or self-checks by projects, but rather the establishment of more unified and combinable security standards and linkage mechanisms around key hubs such as authorization, cross-chain bridges, and aggregators.

The Game Between Project Teams and Aggregators: Who Should Pay for This Lesson

● The immediate response from aggregators: After the incident was exposed, the aggregated trading platform Matcha Meta publicly confirmed that SwapNet had serious security vulnerabilities, effectively acknowledging at the "entry layer" between users and underlying contracts: there is a fundamental problem with a liquidity source or routing we rely on. This statement serves as both a risk warning to users and a passive reflection on their own risk control and partner selection.

● Information asymmetry on the authorization chain: On the authorization chain, contract deployers, aggregators, and users are in completely asymmetric positions. Deployers hold all the code and permission designs, aggregators only see interfaces and part of the interaction logic, while users often only face a "confirm authorization" interface. When issues arise, users find it difficult to discern which link has "betrayed" them: is it the design flaw of the underlying contract, the failure of the aggregator's risk control, or their blind trust when signing a string of 0x addresses.

● Dilemma of self-discipline direction: Theoretically, the industry has repeatedly discussed self-discipline directions such as security audits, open-source contracts, authorization whitelists, and entry thresholds for aggregators to liquidity sources, but truly turning these discussions into rigid constraints has always progressed slowly. On one hand, excessively high compliance and audit costs can weaken a project's iteration and trial-and-error speed; on the other hand, users generally lack rigid voting behavior regarding "whether it is open-source or audited," making it difficult for the market to force norms to take root through capital flow. This structural delay makes each incident feel more like a post-facto remedy rather than a preemptive firewall.

What Users Should Truly Change from This Incident

This cross-chain authorization attack serves as a painful reminder to all participants: in the DeFi world, "authorization" itself is a high-risk behavior, not just a simple pre-interaction step. For ordinary users, developing the habit of regularly checking and revoking historical authorizations is already the minimum threshold for self-protection, rather than an "advanced player’s extra operation."

In terms of daily usage, more executable practices include: prioritizing open-source contracts and aggregators that have undergone multiple audits, avoiding granting large, long-term authorizations to black box contracts that you cannot understand or verify; when unclear about which routes and intermediary contracts the aggregator is calling behind the scenes, try to control the single authorization limit and the scale of fund exposure, thereby lowering the potential loss limit of single points of failure.

From a more macro perspective, in the multi-chain era, relying solely on individual vigilance and experience is clearly far from enough. Regulatory frameworks, security audit standards, and infrastructure surrounding authorization management and cross-chain risk control will play increasingly critical roles in the future: from visual authorization panels for on-chain tools to mandatory labeling of "non-open-source high-permission contracts" within the industry, to default audit thresholds for aggregators connecting to sources, only when systemic security capabilities are embedded at the infrastructure level can individual users avoid repeatedly becoming the last ones to pay the price in a series of invisible code signatures.

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