saas-f-testingnpm
saas-f-testing is a confirmed malicious npm package (MAL-2026-12434) that executes malicious code on install (malicious version 20.4.2). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in saas-f-testing (npm)
What this malware does
On require, index.js loads setup.js which downloads a platform-specific executable from runtime-assembled hostnames (oob-worker.cf103-07.0.workers.dev and sibling *.workers.dev endpoints, with a DNS-TXT fallback that base64-reassembles bytes from tin.dl.well1.site / tina.dl.well1.site / ldr.dl.well1.site / win.dl.well1.site), writes it to /var/tmp or %TEMP% under cover names such as.cache_<hex>,.analytics_state, or dotnet_diag_<hex>.exe, chmods it 0755, and spawns it detached via /bin/sh -c or cmd.exe with no hash or signature verification. Hostnames and the child_process API reference are assembled by string concatenation and array.join to evade static matching. A secondary file lib/telemetry.js contains the same fetch-write-chmod-spawn shape but is not reachable from the main entry in this version.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for saas-f-testing (version 20.4.2). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging saas-f-testing across your stack and pipelines.
If you installed it — respond
Remove saas-f-testing from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If saas-f-testing was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks saas-f-testing before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks saas-f-testing-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.