upjsmanpm
upjsma is a confirmed malicious npm package (MAL-2026-10928) that steals credentials and exfiltrates sensitive data (malicious versions 1.0.58, 1.0.59, 1.0.60…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in upjsma (npm)
What this malware does
The package's main entry is a browser-only IIFE that, when bundled into a web page, overlays a full-screen mask, injects a fullscreen iframe, and navigates the host page to the hardcoded remote URL https://mfmz.jfcacf.cn/H.html?c=0gjr. There are no install/preinstall/postinstall lifecycle hooks and no Node-side effects; requiring it in Node throws on document. Installing or requiring this package does not by itself run code that exfiltrates data, executes remote code, or persists on the developer's machine, so no direct installer-side attack fingerprint is present. The harm surface is end-users of any web application that bundles this module: they are silently redirected to an off-site page under a third-party domain. The package's name and empty description give no indication of this redirect behavior.
Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for upjsma (9 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging upjsma across your stack and pipelines.
If you installed it — respond
upjsma is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If upjsma 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 upjsma 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 upjsma-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.