MAL-2026-6433

The `rstreams-shard-util` npm package was compromised as part of the Miasma worm campaign targeting the LeoPlatform npm ecosystem. On June 24, 2026, 20 LeoPlatform packages were published within a 3-second window by a threat actor who had taken over the npm account `czirker` belonging to the LeoPlatform organization.

The malicious payload is triggered automatically during `npm install` via a `binding.gyp` file using node-gyp command expansion (`<!(node index.js > /dev/null 2>&1 && echo stub.c)`), which bypasses lifecycle script scanners. The replaced `index.js` (~5.2 MB, obfuscated with ROT-N + AES-128-GCM encryption) deploys a multi-stage worm with the following capabilities:

- Credential theft: Targets npm, GitHub, PyPI, RubyGems, Kubernetes, HashiCorp Vault, AWS (IAM keys, Secrets Manager, IMDS), 1Password, JFrog Artifactory, and SSH keys. - AI tool targeting: Exfiltrates configuration files for Claude, Cursor, Gemini, and VS Code. - Worm propagation: Enumerates npm packages and auto-publishes version bumps to spread to other maintainers in the ecosystem. - GitHub persistence: Creates orphan `snapshot-<hex>` branches with fake "Dependabot Updates" workflows to maintain access after initial compromise.

Any system that installed this version should be considered fully compromised. Rotate all secrets immediately from a separate, clean machine. See the linked SafeDep report for full payload analysis, indicators of compromise, and remediation guidance.

--- _-= Per source details. Do not edit below this line.=-_

## Source: amazon-inspector (5b8add0d2dc18ec5b953eb3d02c8926b2f186cc25b8e6cfa76fb4a6123d6aaf9) The package ships a binding.gyp whose sources field at line 6 uses GYP command-expansion syntax (`<!(...)`). When npm installs a package containing binding.gyp, it implicitly runs `node-gyp rebuild`, and the GYP configure step evaluates `<!(...)` expressions as shell commands — executing arbitrary code on the installer's machine without any declared install/postinstall lifecycle script. This mechanism is functionally equivalent to a postinstall hook but is far less visible to reviewers, since package.json shows no lifecycle scripts. The package contains no legitimate native source files that would justify a binding.gyp, indicating the file's only purpose is to trigger the embedded shell command on install.