{"investigation":{"slug":"asterafi","entity_name":"Astera.fi","trust_score":38,"severity_base":null,"score_modifier":0,"confidence":0.62,"status":"published","content_type":"investigation","summary":"Astera.fi is a DeFi credit facility and lending protocol operating on Ethereum's Linea Layer-2 network, issuing the asUSD stablecoin through both over- and under-collateralized mechanisms. On October 9, 2025, the protocol suffered a flash loan exploit via a liquidity index inflation attack that drained approximately $821,856–$880,000 across three lending pools. The protocol has been flagged by ZachXBT and market data indicates near-zero trading activity for asUSD, with the token appearing to have effectively ceased normal operation post-exploit.","sections":[{"content":"Astera.fi describes itself as 'Ethereum's native credit layer,' operating as a DeFi-native credit facility on the Linea ZK-rollup network. The protocol issues asUSD, a stablecoin backed by a combination of over-collateralized and under-collateralized positions, with yield designed to flow to token holders rather than to centralized stablecoin issuers such as Circle or Tether. The core product suite includes Astera Lend (a lending marketplace where users supply ETH, BTC, and stablecoin assets to earn yield from borrowers), asUSD (the native stablecoin minted via collateral deposits or protocol credit lines), and a forthcoming Staked asUSD vault. The protocol leverages modular smart contracts called Facilitators that mint and burn asUSD autonomously while maintaining isolated risk buckets per strategy. Astera claims integration with Linea's ecosystem and has positioned itself as Linea's native stablecoin infrastructure. The protocol had been audited by Trail of Bits and Spearbit prior to launch, according to its own marketing materials. Smart contract code is available on the Astera Finance GitHub organization, which hosts the core lending protocol (Solidity), the asUSD contract, vault implementation, and whitepapers. The documentation explicitly states the protocol is 'a work-in-progress' and that documents 'are subject to change without notice.'","heading":"Protocol Overview","sources":[{"url":"https://docs.astera.fi/","name":"docs.astera.fi","type":"other","credibility":3},{"url":"https://docs.astera.fi/core-architecture/astera-ethereums-native-credit-layer","name":"docs.astera.fi","type":"other","credibility":3},{"url":"https://github.com/Astera-Finance","name":"github.com","type":"other","credibility":3},{"url":"https://liquidity.land/blog/what-is-asterafi","name":"liquidity.land","type":"other","credibility":3}],"severity":"medium"},{"content":"On October 9, 2025, the Astera lending protocol on Linea was exploited via a flash loan attack that leveraged a liquidity index inflation vulnerability. The attacker manipulated the protocol's internal liquidity index, which enabled overvaluation of collateral within the lending pools, and then executed a borrow-drain cycle to extract funds. The attack affected three minipools: asUSD, LINEA, and WETH. Reported losses range from $821,856 (per the DeFi Rekt Report for October 2025) to estimates exceeding $880,000 (approximately 8% of Astera's total value locked at the time), depending on the source. Linea's security team detected the attack pattern during the incident, cut off the attacker's path, and froze compromised funds within minutes, subsequently alerting the Astera team and coordinating mitigation alongside external security researchers. Astera publicly acknowledged working overnight with Linea and Spearbit during the incident. This exploit was ranked as the fifth-largest DeFi hack of October 2025 among the nine exploits that collectively resulted in $38.6 million in losses that month. The attack represented a noted resurgence of flash loan attacks as a threat vector in that period. No recovery of stolen funds has been publicly confirmed.","heading":"October 2025 Flash Loan Exploit","sources":[{"url":"https://de.fi/blog/defi-rekt-report-october-2025-38-6-million-lost-across-9-exploits","name":"de.fi","type":"other","credibility":3},{"url":"https://metamask.io/news/metamask-security-report-october-2025","name":"metamask.io","type":"other","credibility":3}],"severity":"medium"},{"content":"ZachXBT, a widely recognized on-chain investigator who joined Paradigm as an incident response advisor in February 2025, flagged Astera.fi. The specific nature and timing of the flag have not been independently verified via a primary source URL, as ZachXBT's posts are primarily on X (formerly Twitter) and are not indexed in accessible archives at the time of this investigation. The flagging is consistent with ZachXBT's documented pattern of alerting to active exploits, post-exploit risks, and protocols exhibiting suspicious behavior. The protocol's asUSD stablecoin market data shows near-zero trading volume and a market capitalization of approximately $142,000–$170,000, with CoinGecko reporting that ASUSD tokens had stopped trading across all listed exchanges as of late 2025. These market signals are consistent with a protocol in distress or wind-down. Community reports indicate a treasury-led exit process requiring users to manually send asUSD tokens to the official Astera treasury address in order to receive underlying collateral back, a non-standard recovery mechanism that carries counterparty risk. These claims are derived primarily from community-aggregated sources and the risk level of the treasury exit claim should be treated as medium confidence until confirmed via a primary announcement from the Astera team.","heading":"ZachXBT Flag and Community Concerns","sources":[{"url":"https://x.com/asterafinance","name":"x.com","type":"other","credibility":3},{"url":"https://www.coingecko.com/en/coins/astera-usd","name":"coingecko.com","type":"other","credibility":3},{"url":"https://dropstab.com/coins/astera-usd","name":"dropstab.com","type":"other","credibility":3}],"severity":"medium"},{"content":"The asUSD token (ticker: ASUSD) is listed on CoinGecko and tracked on MEXC and LBank, but has experienced a near-complete collapse in trading activity. The circulating supply stands at approximately 12 million ASUSD, corresponding to a total market capitalization of roughly $142,000–$170,000 USD. CoinGecko data indicated that ASUSD had stopped trading on all listed exchanges as of late 2025. The 24-hour trading volume was reported at less than $5 as of the time of this investigation. These metrics are characteristic of a protocol experiencing a wind-down or operating in a state of distress following the October 2025 exploit. The protocol does not appear to have issued a public governance token distinct from asUSD. The low market cap and cessation of exchange trading substantially increase liquidity risk for any remaining holders, and the manual collateral recovery process described in community sources introduces additional operational and counterparty risk.","heading":"Token and Market Status","sources":[{"url":"https://www.coingecko.com/en/coins/astera-usd","name":"coingecko.com","type":"other","credibility":3},{"url":"https://www.mexc.com/price/astera-usd","name":"mexc.com","type":"other","credibility":3},{"url":"https://dropstab.com/coins/astera-usd","name":"dropstab.com","type":"other","credibility":3}],"severity":"medium"},{"content":"Astera.fi's founding team and core contributors are not publicly identified in the protocol's documentation, website, or GitHub organization. The team operates under a model that, based on available public materials, appears to be pseudonymous or deliberately low-profile, with no named founders, LinkedIn profiles, or attributed team members discoverable through open-source research. The protocol's GitHub organization (Astera-Finance) lists seven repositories, including the core lending protocol, asUSD contract, vault implementation, and whitepapers, but does not identify individual contributors by legal name. The absence of disclosed team identities limits accountability in the event of fund loss, regulatory action, or protocol failure. This characteristic is common to early-stage DeFi protocols but is a material risk factor when combined with a documented exploit and alleged wind-down activity. Claims that the protocol traces roots to Astherus and received advisory involvement from figures in the Binance ecosystem have been aggregated from community and secondary sources and have not been confirmed via a primary source.","heading":"Team Transparency and Identity","sources":[{"url":"https://github.com/Astera-Finance","name":"github.com","type":"other","credibility":3},{"url":"https://docs.astera.fi/","name":"docs.astera.fi","type":"other","credibility":3}],"severity":"medium"},{"content":"Astera.fi's marketing materials state the protocol was audited by Trail of Bits and Spearbit, two well-regarded smart contract security firms. Trail of Bits is a security research consultancy that has reviewed complex DeFi and cryptographic systems since 2012. Spearbit is a network of expert security engineers specializing in Web3 smart contract reviews. Despite these audits, the protocol suffered a flash loan exploit in October 2025 that leveraged a liquidity index inflation vulnerability, suggesting that either the audit did not cover the attack surface that was exploited, the vulnerability was introduced after the audit, or the audit findings were not fully remediated. Public links to the specific audit reports for Astera.fi have not been located through open-source research. The Astera Finance GitHub repository does not appear to contain published audit PDFs in its accessible repositories. The exploit underscores that audit coverage does not guarantee protection against all attack vectors, particularly novel price manipulation and flash loan mechanics in lending markets.","heading":"Smart Contract Security and Audit History","sources":[{"url":"https://liquidity.land/blog/what-is-asterafi","name":"liquidity.land","type":"other","credibility":3},{"url":"https://github.com/Astera-Finance","name":"github.com","type":"other","credibility":3},{"url":"https://de.fi/blog/defi-rekt-report-october-2025-38-6-million-lost-across-9-exploits","name":"de.fi","type":"other","credibility":3}],"severity":"medium"},{"content":"Astera.fi operates exclusively on Linea, an Ethereum Layer-2 ZK-rollup developed by Consensys, the blockchain software company founded by Ethereum co-founder Joseph Lubin. Linea ships as a default network in MetaMask, which has approximately 30 million monthly active users. Astera has been described as Linea's native stablecoin infrastructure, and the protocol's liquidity venue (Etherex) is the primary secondary market for asUSD. Linea's centralized sequencer architecture played a dual role in the October 2025 exploit response: the network was able to intervene rapidly to detect the attack, freeze funds, and cut off the attacker's path, demonstrating an incident response capability. However, this architecture also means Linea operators can censor transactions, alter state, or pause the sequencer unilaterally, which represents a trust assumption for users of protocols like Astera that operate on the chain. The sequencer was previously paused during the June 2024 Velocore DEX exploit ($6.8 million), establishing a precedent for centralized intervention. Users of Astera are therefore exposed not only to Astera's own smart contract risk but also to governance and operational decisions made by Linea/Consensys.","heading":"Linea Ecosystem Context and Centralization Risk","sources":[{"url":"https://docs.astera.fi/core-architecture/defis-full-stack-advantage","name":"docs.astera.fi","type":"other","credibility":3},{"url":"https://de.fi/blog/defi-rekt-report-october-2025-38-6-million-lost-across-9-exploits","name":"de.fi","type":"other","credibility":3},{"url":"https://metamask.io/news/metamask-security-report-october-2025","name":"metamask.io","type":"other","credibility":3}],"severity":"medium"}],"timeline":[{"date":"2023","event":"Astera.fi Token Generation Event (TGE) occurred, with the protocol alleged to have raised approximately $5 million. Exact date within early 2023 is unverified.","source":"","date_original":"2023-01-01"},{"date":"2024-06-02","event":"Velocore DEX on Linea exploited for approximately $6.8 million; Linea sequencer halted in response, establishing precedent for centralized chain-level intervention on Linea.","source":""},{"date":"2025-10-09","event":"Astera lending protocol exploited via flash loan and liquidity index inflation attack on Linea. Losses estimated between $821,856 and $880,000 across three minipools (asUSD, LINEA, WETH). Linea security team and Spearbit engaged in incident response.","source":""},{"date":"2025-10","event":"October 2025 DeFi Rekt Report documents Astera exploit as the fifth-largest of nine exploits totaling $38.6 million in losses for the month.","source":"","date_original":"2025-10-01"},{"date":"2025-11","event":"asUSD trading volume reported near zero; CoinGecko data indicates token stopped trading on all listed exchanges. Approximate date based on available market data.","source":"","date_original":"2025-11-01"},{"date":"2026-05","event":"asUSD market capitalization at approximately $142,000–$170,000 with near-zero 24-hour trading volume. Protocol operational status remains unclear; community reports reference a treasury-led collateral recovery process.","source":"","date_original":"2026-05-01"}],"sources_used":[{"url":"https://docs.astera.fi/","name":"docs.astera.fi","type":"other","archive_url":"http://web.archive.org/web/20251002114021/https://docs.astera.fi/","credibility":3,"archive_timestamp":"2025-10-02T11:40:21+00:00"},{"url":"https://docs.astera.fi/core-architecture/astera-ethereums-native-credit-layer","name":"docs.astera.fi","type":"other","archive_url":null,"credibility":3,"archive_error":"error:no-job","archive_status":"unarchivable","archive_timestamp":null},{"url":"https://github.com/Astera-Finance","name":"github.com","type":"other","archive_url":"https://web.archive.org/web/20260829075853/https://github.com/Astera-Finance","credibility":3,"archive_timestamp":"2026-08-29T07:58:53+00:00"},{"url":"https://liquidity.land/blog/what-is-asterafi","name":"liquidity.land","type":"other","archive_url":null,"credibility":3,"archive_error":"error:no-job","archive_status":"unarchivable","archive_timestamp":null},{"url":"https://de.fi/blog/defi-rekt-report-october-2025-38-6-million-lost-across-9-exploits","name":"de.fi","type":"other","archive_url":"http://web.archive.org/web/20260816034704/https://de.fi/blog/defi-rekt-report-october-2025-38-6-million-lost-across-9-exploits","credibility":3,"archive_timestamp":"2026-08-16T03:47:04+00:00"},{"url":"https://metamask.io/news/metamask-security-report-october-2025","name":"metamask.io","type":"other","archive_url":"http://web.archive.org/web/20260410101946/https://metamask.io/news/metamask-security-report-october-2025","credibility":3,"archive_timestamp":"2026-04-10T10:19:46+00:00"},{"url":"https://x.com/asterafinance","name":"x.com","type":"other","archive_url":null,"credibility":3,"archive_timestamp":null},{"url":"https://www.coingecko.com/en/coins/astera-usd","name":"coingecko.com","type":"other","archive_url":"http://web.archive.org/web/20250831232155/https://www.coingecko.com/en/coins/astera-usd","credibility":3,"archive_timestamp":"2025-08-31T23:21:55+00:00"},{"url":"https://dropstab.com/coins/astera-usd","name":"dropstab.com","type":"other","archive_url":"http://web.archive.org/web/20250917045032/https://dropstab.com/coins/astera-usd","credibility":3,"archive_timestamp":"2025-09-17T04:50:32+00:00"},{"url":"https://www.mexc.com/price/astera-usd","name":"mexc.com","type":"other","archive_url":null,"credibility":3,"archive_error":"error:not-found","archive_status":"unarchivable","archive_timestamp":null},{"url":"https://docs.astera.fi/core-architecture/defis-full-stack-advantage","name":"docs.astera.fi","type":"other","archive_url":"http://web.archive.org/web/20250926133147/https://docs.astera.fi/core-architecture/defis-full-stack-advantage","credibility":3,"archive_timestamp":"2025-09-26T13:31:47+00:00"}],"source_tags":["defillama"],"addresses":[],"reviewed":false,"reviewed_by":null,"model_used":"claude-sonnet-4-6","created_at":"2026-05-04T02:54:20.78626+00:00","updated_at":"2026-08-30T03:54:59.136997+00:00"}}