MAL-2026-12555 Malicious code in checkout-desktop-cashback (npm)
Malicious package
Published
MAL-2026-12555 is a malicious package: checkout-desktop-cashback (npm). Every version was published to cause harm.
Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.
Reference: https://insights.sbomify.com/MAL-2026-12555/ (Markdown: https://insights.sbomify.com/MAL-2026-12555/index.md)
- Package
- checkout-desktop-cashback
- Registry
- npm
What is MAL-2026-12555?
MAL-2026-12555 is a malicious package in checkout-desktop-cashback, published on 5 Aug 2026.
Official description
On require('checkout-desktop-cashback'), index.js loads vendor.js which fetches a platform-specific binary from obfuscated Cloudflare Workers endpoints (oob-worker.cf103-070.workers.dev, cf100-416/cf102-baf/cf101-adf.workers.dev), with a DNS-TXT covert-channel fallback over *.dl.wel1.ru (sdk/ext/pkg/net.dl.wel1.ru) that base64-decodes chunked payload records. The fetched bytes are written to /tmp or %TEMP% under a disguised name ('.cache<hex>' on POSIX, 'dotnet_diag_<hex>.exe' on Windows), chmod 0755, and spawned detached via '/bin/sh -c' or 'cmd'. Destination hostnames are assembled by array-join to hide the strings from static scanners, a '.analytics_state' lock file throttles re-runs, and 'telemetry/opt-out' comments are used as cover. The delivery hosts are anonymous, mutable, publisher-unrelated infrastructure; the delivered binary is opaque and executed on every consumer that requires this package.
What should I do about MAL-2026-12555?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.