Unpacking the AsyncAPI npm supply chain compromise and import-time payload delivery

In this article Attack chain overview How the attack started: GitHub Actions pwn request Mitigation and protection guidance Learn more On July 14, 2026, Microsoft Threat Intelligence identified a coordinated supply chain compromise of the @asyncapi npm organization, a widely used set of packages for the AsyncAPI specification and code generation. Five package versions across four package names were republished within roughly ninety minutes, each carrying the same maliciously injected loader: @asyncapi/specs (in both the 6.11.2-alpha.1 prerelease and 6.11.2 stable release), @asyncapi/[email protected], @asyncapi/[email protected], and @asyncapi/[email protected]. Because @asyncapi/specs is a transitive dependency of numerous AsyncAPI tooling packages, this attack affected developer workstations, CI/CD pipelines, container builds, or production services that resolved and imported the affected versions during the exposure window. Unlike the more common postinstall-hook supply-chain pattern, this campaign executes at module-load (import/require) time. When any consuming build or application imports a poisoned package, the injected block runs immediately. Because the trigger is an import rather than an install script, the common npm install –ignore-scripts mitigation does not neutralize it. The second stage decrypts and evaluates a Miasma modular runtime with active command and control (C2), persistence, and decentralized fallback channels. Although disabled in this instance, credential-harvesting, propagation, and additional high-risk modules could be enabled through persistence. Microsoft Defender Antivirus detects and blocks malicious artifacts as Trojan:JS/MiasmStealer.SC and Trojan:Script/Supychain.A . Microsoft Defender for Endpoint provides behavioral coverage for the suspicious detached Node.js process spawn, IPFS retrieval, and persistence activity. Organizations should immediately remove all five affected versions, purge npm and Yarn caches, hunt for sync.js under the NodeJS masquerade directories, block outbound connections to 85.137.53[.]71 on ports 8080, 8081, and 8091, and rotate all credentials accessible from any environment that imported the compromised packages. Detailed hunting queries, indicators of compromise, and mitigation guidance are provided in the succeeding sections. Attack chain overview Figure 1. End-to-end attack chain from CI/CD pipeline compromise through import-time execution to IPFS second-stage fetch, with C2 infrastructure and affected packages. The compromise originated from a pwn request against asyncapi/generator. A misconfigured GitHub Actions workflow ( pull_request_target ) executed attacker-controlled pull-request (PR) code, exposed the asyncapi-bot personal access token (PAT), and enabled unauthorized pushes to auto-publish branches. The legitimate GitHub Actions OpenID Connect (OIDC) release workflows then published the poisoned packages under the automated identity npm-oidc-no-reply@git