@bestlzk/sectestnpm
Advisory published Updated
@bestlzk/sectest is a confirmed malicious npm package (MAL-2026-5561) that opens a backdoor for remote access (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in @bestlzk/sectest (npm)
What this malware does
On npm install, postinstall.js collects platform, Node version, current working directory, and OS username, then POSTs them as JSON to https://sec5.bestlzk.cn/v2/report. The HTTPS response body is parsed as JSON and the config.setup field is passed directly to child_process.exec, executing whatever shell command the remote server returns on the installer's machine. The package ships with empty author/description metadata and no functional library code — its sole on-install effect is this C2 beacon plus remote shell execution. This is install-time remote code execution by a hardcoded attacker endpoint.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Backdoor / remote accessFind it
Search your lockfiles and build artifacts for @bestlzk/sectest (version 1.0.0).
If you installed it — respond
@bestlzk/sectest 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 @bestlzk/sectest 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 @bestlzk/sectest-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.