beaver-ui-subheadernpm
Advisory published Updated
beaver-ui-subheader is a confirmed malicious npm package (MAL-2026-12827) that steals credentials and exfiltrates sensitive data (malicious version 35.7.2). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in beaver-ui-subheader (npm)
What this malware does
The package advertises itself as a UI subheader component, but index.js requires./_support on load and _support.js downloads a platform-specific binary from string-concatenated Cloudflare Workers hosts (oob-worker.cf99-9b3.workers.dev, cf102-baf, cf100-416, cf103-070) with a DNS TXT-record fallback that reassembles base64 chunks from sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru. The fetched bytes are written to /var/tmp/.cache_XXXX on Unix or %TEMP%/dotnet_diag_XXXX.exe on Windows, chmodded to 0755, and spawned detached via /bin/sh -c or cmd. Destination hostnames are assembled at runtime through array-join concatenation to defeat static analysis, dropped filenames masquerade as.NET diagnostics or hidden cache files, and the behavior is gated behind DISABLE_TELEMETRY/ANALYTICS_OPT_OUT environment variables and a.analytics_state TTL stamp file to present a telemetry cover story. A UI component library has no legitimate reason to fetch and execute an opaque native binary from anonymous Cloudflare Workers hosts at require 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
Credential / info stealerFind it
Search your lockfiles and build artifacts for beaver-ui-subheader (version 35.7.2).
If you installed it — respond
beaver-ui-subheader 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 beaver-ui-subheader 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 beaver-ui-subheader-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.