preinstall-hook-webhook-callback-demonpm
preinstall-hook-webhook-callback-demo is a confirmed malicious npm package (MAL-2026-14016) that steals credentials and exfiltrates sensitive data (malicious versions 1.0.0, 1.0.1). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in preinstall-hook-webhook-callback-demo (npm)
What this malware does
package.json declares a preinstall lifecycle script that contacts webhook.site, an ephemeral request-capture service commonly used as an attacker-controlled exfiltration sink. The hook fires automatically on npm install before any user interaction, and webhook.site is not a first-party or documented destination for any legitimate build or runtime purpose of this package. The combination of an auto-executing preinstall script wired to an out-of-band capture endpoint is the shape of installer-side data exfiltration / callback beaconing at install time.
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 preinstall-hook-webhook-callback-demo (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging preinstall-hook-webhook-callback-demo across your stack and pipelines.
If you installed it — respond
preinstall-hook-webhook-callback-demo 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 preinstall-hook-webhook-callback-demo 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 preinstall-hook-webhook-callback-demo 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 preinstall-hook-webhook-callback-demo-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.