@jaymara/jsononifiernpm
Malicious code in @jaymara/jsononifier (npm) Remove it immediately and rotate any exposed credentials.
What this malware does
@jaymara/[email protected] is advertised as a JSON formatting utility but ships a covert command-execution primitive that fires on require. index.js loads trigger.js, which checks for sandbox indicators (process.env.CI==='true', NODE_ENV==='test', existence of /.dockerenv) and the platform (win32); when those checks indicate a real Windows workstation, it schedules Executer.js via process.nextTick + setTimeout(5000). Executer.js XOR-decodes a byte array from payload.js using key 'xorkey123' and passes the resulting string to child_process.exec with { windowsHide: true }. payload.js openly comments the intent ('XOR-encoded command – not visible in source'). The current decoded value is a demo (calc.exe), but the mechanism — opaque encoded bytes decoded at runtime and handed to exec, gated to skip CI/test/Docker and only fire on real victim machines — is the attack: a future tarball can swap the byte array for any command without changing the visible code. None of this is required by, or consistent with, a JSON formatter.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for @jaymara/jsononifier (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging @jaymara/jsononifier across your stack and pipelines.
If you installed it — respond
Remove @jaymara/jsononifier from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If @jaymara/jsononifier was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks @jaymara/jsononifier before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks @jaymara/jsononifier-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.