tinkoff-fb-service-prefill-profile-contactnpm
tinkoff-fb-service-prefill-profile-contact is a confirmed malicious npm package (MAL-2026-12243) that executes malicious code on install (malicious version 20.2.3). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in tinkoff-fb-service-prefill-profile-contact (npm)
What this malware does
On require of the package's main entry, vendor.js downloads a platform-specific executable from anonymous Cloudflare Workers hosts under oob-worker.cfNNN-XXX.workers.dev (host strings assembled via split-and-join fragments to evade static analysis) and, on failure, reassembles a base64-encoded payload from sequential DNS TXT record lookups against subdomains of *.dl.well1.site (tin.dl.well1.site, ldr.dl.well1.site). The fetched bytes are written to /var/tmp or %TEMP% under disguised names (.cache<hex>, dotnet_diag_<hex>.exe,.analytics_state), chmod 0755, then spawned detached via spawn('/bin/sh', ['-c', '<fp> &']) on Unix or spawn('cmd', ['/c','start','/b',...]) on Windows. There is no version pinning, no hash or signature verification, and comments frame the behavior as 'telemetry/analytics' unrelated to the package's advertised Tinkoff SDK prefill purpose. The DNS-TXT reassembly path is a covert delivery channel designed to bypass HTTPS egress filtering.
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 tinkoff-fb-service-prefill-profile-contact (version 20.2.3). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging tinkoff-fb-service-prefill-profile-contact across your stack and pipelines.
If you installed it — respond
Remove tinkoff-fb-service-prefill-profile-contact 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 tinkoff-fb-service-prefill-profile-contact 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 tinkoff-fb-service-prefill-profile-contact 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 tinkoff-fb-service-prefill-profile-contact-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.