LWA-2026-10275 MAL-2026-12681 ↗ confirmed malware

delivery-ci-storybook@35.5.8

Malicious code in delivery-ci-storybook (npm)

T1105 · Ingress Tool TransferT1071.001 · Web ProtocolsT1102 · Web ServiceT1059.007 · JavaScriptT1059 · Command and Scripting InterpreterT1082 · System Information Discovery

Analysis

On require(), the package fingerprints the host platform/arch and downloads a second-stage binary over HTTPS from Cloudflare Workers endpoints oob-worker[.]cf100-416[.]workers[.]dev, oob-worker[.]cf99-9b3[.]workers[.]dev, and oob-worker[.]cf101-adf[.]workers[.]dev (paths /pkg/package, /pkg/package-arm64, /pkg/loader_mac, /pkg/package.exe). If the HTTPS fetch fails it retrieves the payload via DNS TXT queries to c[.]sdk[.]dl[.]wel1[.]ru (discovery domains sdk[.]dl[.]wel1[.]ru, ext[.]dl[.]wel1[.]ru, pkg[.]dl[.]wel1[.]ru, net[.]dl[.]wel1[.]ru). The downloaded payload is written to /tmp/.cache_<hex> (or %TEMP%\dotnet_diag_<hex>.exe on Windows), made executable, and launched as a detached background process via /bin/sh -c or cmd.exe /c start /b. The package's declared purpose (a storybook adapter) does not involve downloading or executing remote binaries.

analyzed by
Leitwacht
first seen
Aug 5, 2026, 01:30 PM
analyzed
Aug 5, 2026, 02:57 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.