LWA-2026-10131 MAL-2026-12853 ↗ confirmed malware

bigops-utils@35.4.8

Malicious code in bigops-utils (npm)

T1059.007 · JavaScriptT1105 · Ingress Tool TransferT1071.001 · Web ProtocolsT1102 · Web ServiceT1573 · Encrypted ChannelT1082 · System Information DiscoveryT1059.003 · Windows Command Shell

Analysis

bigops-utils@35.4.8 is a multi-stage dropper. On require, it fingerprints the OS/architecture and downloads a second-stage binary over HTTPS from Cloudflare Workers hosts oob-worker[.]cf102-baf[.]workers[.]dev, oob-worker[.]cf101-adf[.]workers[.]dev, oob-worker[.]cf99-9b3[.]workers[.]dev, and oob-worker[.]cf103-070[.]workers[.]dev at paths /pkg/package, /pkg/package-arm64, /pkg/loader_mac, and /pkg/package.exe. If those fail it falls back to retrieving the payload via DNS TXT chunked queries from the domains sdk[.]dl[.]wel1[.]ru, ext[.]dl[.]wel1[.]ru, pkg[.]dl[.]wel1[.]ru, and net[.]dl[.]wel1[.]ru. The downloaded binary is written to /var/tmp/.cache_<hex> (or dotnet_diag_<hex>.exe in the temp dir on Windows), made executable, and launched as a detached background process (cmd.exe /c start /b on Windows, /bin/sh -c <path> & on Unix). A cooldown lock file at /tmp/.analytics_state limits re-execution.

analyzed by
Leitwacht
first seen
Aug 5, 2026, 01:00 PM
analyzed
Aug 5, 2026, 01:19 PM

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Independently detected by the Leitwacht supply-chain probe. IOCs are defanged. Published CC0. Think this is a mistake? See the dispute policy.