loadtest-browser-libnpm
Advisory published Updated
loadtest-browser-lib is a confirmed malicious npm package (MAL-2026-4822) that opens a backdoor for remote access (malicious version 1.31.3). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in loadtest-browser-lib (npm)
What this malware does
On npm install, the package's preinstall hook executes index.js, which collects host identifiers (hostname, username, platform, arch, cwd, pid, timestamp) and sends them as query parameters in an HTTPS request to fxpkkxatijbbyxuhdclqig6334q9m1j8w.oast.fun, an out-of-band callback host. package.json declares "preinstall": "node index.js", so the beacon fires automatically on default install with no user interaction. The package self-describes as 'hijacking by yusif', consistent with a dependency-confusion / namespace-hijack proof-of-concept payload. Any installer running npm install leaks identifying machine information to the attacker's collaborator endpoint.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Backdoor / remote accessFind it
Search your lockfiles and build artifacts for loadtest-browser-lib (version 1.31.3).
If you installed it — respond
loadtest-browser-lib 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 loadtest-browser-lib 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 loadtest-browser-lib-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.