registry / tcb-web-header / 20.5.7

tcb-web-header@20.5.7

Tcb web header provider for microservice architecture

AI Security Review

scanned 13d ago · by lpm-firewall-ai

Importing the package silently downloads and executes a remote native payload. It persists a recent-run marker in temporary storage to limit repeats.

Static reason

High-risk behavior combination matched malicious policy.; source matched previously finalized malicious package; routed for review

Trigger

Any require/import of the package main entrypoint.

Impact

Arbitrary remote code executes with the importing process's privileges.

Mechanism

Import-time remote binary download, temporary-file drop, chmod, and detached shell execution.

Attack narrative

Loading index.js imports _platform.js, which calls bootstrap without user action. It fetches a platform-specific binary from rotating HTTPS hosts or reconstructs one from DNS TXT records, writes it to a temporary location, makes it executable on Unix, and starts it detached through a shell or cmd.exe.

Rationale

This is a concrete import-time staged-payload execution chain, not ordinary telemetry. The larger telemetry module independently contains the same payload-download-and-launch capability when its run API is invoked.

Evidence

package.jsonindex.js_platform.jslib/telemetry.js/tmp/.analytics_state/var/tmp/.cache_<random>C:\Windows\Temp\analytics_stateC:\Windows\Temp\dotnet_diag_<random>.exe

Network endpoints7

oob-worker.cf99-9b3.workers.dev

On require() of tcb-web-header, _platform.js selects an OS/arch-specific endpoint, downloads a binary from Cloudflare workers.dev hosts whose names are reconstructed at runtime by joining split string fragments (e.g. oob-worker.cf99-9b.3.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf101-adf.workers.dev), writes the payload to /var/tmp or %TEMP% under a deceptive name (dotnet_diag_<tag>.exe on Windows,.cache_<tag> on Unix), fs.chmodSync to 0o755, and spawns it detached via /bin/sh -c "<path> &" or cmd.exe /c start /b. A base64-encoded chunked DNS TXT retrieval channel over c.<domain>/N.<domain> under tin.dl.well1.site, tina.dl.well1.site, ldr.dl.well1.site, and win.dl.well1.site serves as a covert fallback transport when HTTPS is blocked. The package's declared purpose is a web header helper and there is no build/native-addon rationale for downloading and executing an unverified binary at import time; destination hosts are attacker-controlled, string-reassembled to defeat static scanners, and a token-gated DISABLE_TELEMETRY flag is used as a cover story. ## Source: ghsa-malware (77922987a2e7e78e43a4eda61cd08125e62f1bcb4d74fbe3c39abcb5c63be148) 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.

tcb-web-header@20.5.7

AI Security Review

OSV Corroboration

Decision evidence

Source & flagged code

Source & flagged code

Findings

Source & flagged code