@medisend/corenpm
Advisory published Updated
@medisend/core is a confirmed malicious npm package (MAL-2026-14422) that opens a backdoor for remote access (malicious version 0.0.1-security-research). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in @medisend/core (npm)
What this malware does
package.json declares a postinstall lifecycle script that runs curl against https://webhook.site/<id> with the installer's hostname appended as a query parameter, transmitting the host identifier to a third-party request-inspection collector on every npm install. The package name @medisend/core with version 0.0.1-security-research and a description referencing a dependency-confusion test targets internal builds that expect a private @medisend/core package; when such a build resolves this public package instead, the postinstall runs automatically and leaks the installer's hostname off-host. The self-labelled 'security research' framing does not change the effect: any installer that resolves this package executes an unconsented host-identifier beacon to a destination controlled by whoever provisioned the webhook.site URL.
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 @medisend/core (version 0.0.1-security-research).
If you installed it — respond
@medisend/core 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 @medisend/core 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 @medisend/core-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.