Microsoft Threat Intelligence
Microsoft has identified a supply chain attack on the Mastra-AI npm ecosystem, with 80+ packages compromised through npm account takeover. The attacker introduced a phantom dependency into the compromised packages. The malicious dependency was published by a single anonymous maintainer less than 24 hours ago. The compromised mastra@1.13.1 adds the dependency easy-day-js@^1.11.21 (typosquat of "dayjs"), which resolves to v1.11.22. The post-install script runs node setup.cjs, which downloads and executes a remote payload. The post-install script in easy-day-js@1.11.22: 1. Bypasses TLS: Disables SSL verification (NODE_TLS_REJECT_UNAUTHORIZED=0) to communicate with attacker C2 without certificate errors 2. Writes tracking files: Creates ~/.pkg_history (infected machine path) and ~/.pkg_logs (XOR-encoded marker) to prevent re-infection 3. Downloads hidden payload: Fetches second-stage .js from 23[.]254[.]164[.]92:8000/update/49890878 4. Executes as invisible process: Spawns downloaded payload with C2 endpoint 23[.]254[.]164[.]123:443 passed as argument, runs detached and hidden (windowsHide=true) 5. Covers tracks: Deletes setup.cjs to remove all evidence of initial infection This attack affects mastra@1.13.1, mastra/pg, mastra/mcp, mastra/schema-compat, mastra/ai-sdk, mastra/rag, and 80+ other packages. Microsoft Defender for Endpoint customers should monitor and act on alerts with Trojan:JS/ObfusNpmJs in the title. Customers can also check for the following IOCs: - ls ~/.pkg_history ~/.pkg_logs - random .js files in home/temp directory Users are advised to downgrade to previous versions immediately, use mastra@1.13.0 explicitly, and use lockfiles.
