Malicious code in tcb-web-header (npm)
--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (115bda849ee7aff33e1ccc649f492e892e31243bfb026eea8048c158c885bdf0) 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.
AI Analysis
Technical Summary
Upon requiring the tcb-web-header package version 20.5.7, a platform-specific script dynamically reconstructs Cloudflare worker hostnames to download a binary payload. This payload is saved to temporary system directories with misleading names and executed with elevated permissions. The package uses a base64-encoded DNS TXT record channel as a covert fallback communication method when HTTPS is blocked. The malicious behavior is concealed by obfuscating hostnames and a token-gated DISABLE_TELEMETRY flag. There is no legitimate reason for downloading and executing an unverified binary in a web header helper package, indicating deliberate malicious intent.
Potential Impact
This malicious package can lead to arbitrary code execution on the host system with the privileges of the user running the Node.js process. The covert DNS fallback channel may allow command and control communications even in restricted network environments. This can result in system compromise, data theft, or further malware deployment.
Mitigation Recommendations
No official patch or remediation is currently documented. Users should immediately stop using tcb-web-header version 20.5.7 and remove it from their environments. Audit dependencies for this package and replace it with trusted alternatives. Monitor for suspicious activity related to execution of unexpected binaries in temporary directories. Patch status is not yet confirmed — check the vendor advisory or trusted security sources for updates.
Malicious code in tcb-web-header (npm)
Description
--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (115bda849ee7aff33e1ccc649f492e892e31243bfb026eea8048c158c885bdf0) 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.
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Upon requiring the tcb-web-header package version 20.5.7, a platform-specific script dynamically reconstructs Cloudflare worker hostnames to download a binary payload. This payload is saved to temporary system directories with misleading names and executed with elevated permissions. The package uses a base64-encoded DNS TXT record channel as a covert fallback communication method when HTTPS is blocked. The malicious behavior is concealed by obfuscating hostnames and a token-gated DISABLE_TELEMETRY flag. There is no legitimate reason for downloading and executing an unverified binary in a web header helper package, indicating deliberate malicious intent.
Potential Impact
This malicious package can lead to arbitrary code execution on the host system with the privileges of the user running the Node.js process. The covert DNS fallback channel may allow command and control communications even in restricted network environments. This can result in system compromise, data theft, or further malware deployment.
Mitigation Recommendations
No official patch or remediation is currently documented. Users should immediately stop using tcb-web-header version 20.5.7 and remove it from their environments. Audit dependencies for this package and replace it with trusted alternatives. Monitor for suspicious activity related to execution of unexpected binaries in temporary directories. Patch status is not yet confirmed — check the vendor advisory or trusted security sources for updates.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- MAL-2026-12476
- Osv Schema Version
- 1.7.4
- Ecosystems
- ["npm"]
Threat ID: 6a735745bf8831d539159f47
Added to database: 08/05/2026, 15:31:17 UTC
Last enriched: 08/05/2026, 17:25:17 UTC
Last updated: 09/07/2026, 22:07:52 UTC
Views: 18
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