Malicious Bun Runtime Payload Dropped by Shai Hulud npm Supply Chain Attack

ATT&CK techniques

Initial Access → Execution

Recon
Resource Dev
Initial Access
- T1195.002Compromise Software Supply Chain
Execution
- T1059.007JavaScript
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects creation of the setup_bun.js or bun_environment.js files associated with the Shai Hulud 2.0 npm supply-chain worm. A malicious preinstall script drops setup_bun.js which installs the Bun runtime and stages the large bun_environment.js payload for credential theft and self-propagation. These distinctive filenames written during package installation indicate the worm establishing execution.

Reporting behind it

Related detections9 linkedT1059.007 — drag to rearrange

Suspicious NPM Install Hook Executing Setup Script via Node

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Malicious Shai-Hulud npm Payload Execution via bun_environment Script (via process_creation)

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Suspicious Node Payload Drop in Local Share Directory (via file_event)

Possible React2Shell CVE-2025-55182 Prototype Pollution Exploitation

Suspicious Node.js Script Execution from AppData Roaming

Possible Reflected XSS via cPanel cpanelwebcall Endpoint CVE-2023-29489

Malicious Bun Runtime Payload Dropped by Shai Hulud npm Supply Chain Attack

Pivot detection · T1059.007 · 9 related

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