f0-data-constructornpm
Advisory published Updated
f0-data-constructor is a confirmed malicious npm package (MAL-2023-1491) that opens a backdoor for remote access (malicious versions 1.0.0, 28.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in f0-data-constructor (npm)
What this malware does
The package's preinstall hook auto-executes index.js on npm install. The script imports https and os, collects os.hostname(), os.platform(), os.arch(), os.homedir(), and dns.getServers(), and POSTs the JSON payload to the hardcoded host rb6etzw0lznpijvfl5m5ujmyrpxhl99y.oastify.com at path /hit. oastify.com is Burp Collaborator out-of-band infrastructure; the subdomain uniquely identifies the operator's Collaborator session. The behavior matches a dependency-confusion / typosquat reconnaissance beacon: no documented package purpose, no consent, and the collected fields exist solely to identify the installer host to the operator.
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.
The OpenSSF Package Analysis project identified 'f0-data-constructor' @ 28.0.0 (npm) as malicious.
It is considered malicious because:
- The package communicates with a domain associated with malicious activity.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Backdoor / remote accessFind it
Search your lockfiles and build artifacts for f0-data-constructor (2 malicious versions).
If you installed it — respond
f0-data-constructor establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If f0-data-constructor was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
- OpenSSF: Package Analysis · finder
Detect & block this
O3 blocks f0-data-constructor-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.