OpenSSF/OSV advisory MAL-2026-12477 confirms this npm version as malicious. On `require('tcb-web-images')`, index.js loads _helpers.js which immediately runs a setup routine that selects an OS/arch-specific URL path and downloads a binary over HTTPS from one of four Cloudflare Workers hosts whose names are assembled at runtime by joining string-array fragments (`oob-worker.cf103-070.workers.dev`, `oob-worker.cf101-adf.workers.dev`, `oob-worker.cf100-416.workers.dev`,...
Source
OpenSSF Malicious Packages via OSV
Summary
Malicious code in tcb-web-images (npm)
Details
On `require('tcb-web-images')`, index.js loads _helpers.js which immediately runs a setup routine that selects an OS/arch-specific URL path and downloads a binary over HTTPS from one of four Cloudflare Workers hosts whose names are assembled at runtime by joining string-array fragments (`oob-worker.cf103-070.workers.dev`, `oob-worker.cf101-adf.workers.dev`, `oob-worker.cf100-416.workers.dev`, `oob-worker.cf99-9b3.workers.dev`), with a DNS-TXT chunked fallback under `*.dl.well1.site`. The downloaded bytes are written to `/var/tmp` or `%TEMP%` under disguised names mimicking system utilities (`.cache_<rand>` on Unix, `dotnet_diag_<rand>.exe` on Windows), chmod'd 0755, and detach-spawned via `/bin/sh -c '<path> &'` or `cmd.exe`. A freshness marker is stored as `.analytics_state` and stderr is silenced by a no-op logger. A second, larger copy of the same dropper is shipped as `lib/telemetry.js` under an 'analytics SDK' cover story, using additional string-concatenation obfuscation (`require("child_" + "process")`, `fs["chmod"+"Sync"]`); it is not referenced by the current index.js but is bundled at the tarball root. The package is advertised as a 'lightweight images wrapper' — the dropper behavior is unrelated to that purpose, the destinations are author-controlled and obfuscated to defeat scanners, and the delivered bytes are an opaque native executable with no publisher provenance, integrity check, or version pinning.
Decision reason
OpenSSF Malicious Packages via OSV confirms tcb-web-images@20.5.3 as malicious (MAL-2026-12477): Malicious code in tcb-web-images (npm)