online-headernpm
Advisory published Updated
online-header is a confirmed malicious npm package (MAL-2026-17420) that executes malicious code on install (malicious version 99.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in online-header (npm)
What this malware does
[email protected] is a dependency-confusion squat (name claimed at version 99.0.0 with an inert main entry) whose preinstall lifecycle script runs node callback.js. callback.js collects host identifiers — os.hostname(), os.userInfo().username, __dirname install path, Node version, os.platform() and os.arch() — and POSTs them via https.request to the hardcoded Burp Collaborator OAST endpoint https://bixi2qq8pkzaq6byt1e037kuul0co2cr.oastify.com, with a DNS-based backup channel to the same subdomain. On any build system that resolves online-header from the public registry (for example, an internal package of the same name shadowed by this public release), npm install automatically transmits the installer's host identity and internal install path to a third-party collector controlled by whoever provisioned the OAST subdomain. The package's self-description as a 'dependency-confusion test' does not change the behavior: installers receive no notice and no opt-out, and the data lands at an endpoint outside their control.
The OpenSSF Package Analysis project identified 'online-header' @ 99.0.0 (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
Malicious packageFind it
Search your lockfiles and build artifacts for online-header (version 99.0.0).
If you installed it — respond
Remove online-header 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 online-header 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 online-header-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.