xo-twofanpm
Advisory published Updated
xo-twofa is a confirmed malicious npm package (MAL-2026-11105) that opens a backdoor for remote access (malicious versions 15.0.0, 28.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in xo-twofa (npm)
What this malware does
package.json declares a preinstall script that runs node index.js on npm install. index.js collects host identifiers (os.hostname(), os.platform(), os.arch(), os.homedir(), dns.getServers()) and POSTs them as JSON to the hardcoded host f4k2mnpoengdb7o3etftn7fmkdq5ew5ku.oastify.com (a Burp Collaborator out-of-band interaction endpoint). The beacon fires automatically on install without user interaction and self-describes as a dependency-confusion proof of concept.
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
Backdoor / remote accessFind it
Search your lockfiles and build artifacts for xo-twofa (2 malicious versions).
If you installed it — respond
xo-twofa 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 xo-twofa 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
Detect & block this
O3 blocks xo-twofa-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.