Mini Shai-Hulud Returns: 600+Malicious npm Packages Fake Sigstore Badges in AntV Ecosystem Attack

Endor Labs discovered a significant malware campaign affecting the npm ecosystem on May 19, 2026, identifying 42 initial malicious packages, which later expanded to 633, including many dormant and widely-used packages like jest-canvas-mock and size-sensor. The campaign, propagating swiftly across the AntV ecosystem, utilized a novel method of Sigstore provenance forgery, making malicious packages appear legitimate by embedding a payload that generates valid Sigstore attestations. Attackers targeted dormant accounts, exploiting their inactivity to compromise them with minimal detection risk, and used two types of delivery mechanisms: phantom commit droppers and embedded payloads. The attack also involved credential harvesting and persistence mechanisms, with a primary exfiltration channel disguised as legitimate traffic. The breadth of the compromise suggests the use of a single stolen npm token for the AntV organization, while the worm's ability to produce valid provenance without authorization highlights a need for defensive strategies that do not rely solely on provenance verification.

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