streak-day-utilsnpm
Advisory published Updated
streak-day-utils is a confirmed malicious npm package (MAL-2026-12047) that executes malicious code on install (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in streak-day-utils (npm)
What this malware does
index.mjs schedules an asynchronous routine at module load that decodes a table of hex-encoded strings to reconstruct references to process, fetch, child_process, /mnt/c, AppData, a Backblaze B2 URL, RenameMe.exe, and a VBScript body invoking WScript.Shell.Run hidden. When Node executes under WSL (detected via /mnt/c), the code enumerates Windows user profiles under /mnt/c/Users, downloads helper.tar.gz from https://f004.backblazeb2.com/file/dp8hbvocjd2fpza/helper.tar.gz, extracts it into the victim's AppData\Local\Microsoft\Windows\syscache directory, and writes vite-native-helper.vbs into the Windows Startup folder to auto-launch the extracted RenameMe.exe on every login. The behavior is presented under a 'vite-cache-sync' cover story, and all filesystem paths, the remote URL, and the VBScript payload are hex-obfuscated to conceal the dropper. Installing or importing this package causes cross-boundary WSL-to-Windows code execution and establishes persistence on the Windows host controlled by the package author.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Search your lockfiles and build artifacts for streak-day-utils (version 1.0.0).
If you installed it — respond
Remove streak-day-utils 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 streak-day-utils was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks streak-day-utils-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.