file-type-detectornpm
file-type-detector is a confirmed malicious npm package (MAL-2026-16053) that typosquats a legitimate package to trick installs (malicious versions 1.1.0, 1.1.1). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in file-type-detector (npm)
What this malware does
A clone of file-type-checker with one function added: isSign(name, moduleName, offset) in dist/validation/image.js reads public/${name}.png from the working directory, splits the buffer at -offset, and writes the trailing payload to../../../{moduleName}/log - a sibling package under node_modules - then returns isPNG() so the caller sees a plausible boolean. It is undocumented, reachable only via an __exportStar wildcard so it is never named in dist/index.js, and fails silently on try/catch.
Drop stage of a three-package chain: file-type-detector writes the payload, gloggo (1.1.2-1.1.4) executes it via require('./log'), and sonmors (typosquat of sonner) triggers the chain by requiring gloggo. gloggo shares the npm publisher log-developer and was published five minutes apart on 2026-08-27. No install hooks; execution occurs on require().
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
TyposquatFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for file-type-detector (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging file-type-detector across your stack and pipelines.
If you installed it — respond
file-type-detector is a typosquat — you almost certainly intended a legitimately-named package. Remove file-type-detector, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.
Did it already run?
If file-type-detector 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 file-type-detector 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 file-type-detector-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.