Which versions of checkout-checkout-test-block-aff are malicious?

The following npm versions of checkout-checkout-test-block-aff are flagged malicious: 35.9.6. Treat any of these as compromised.

How do I remediate checkout-checkout-test-block-aff if I installed it?

checkout-checkout-test-block-aff is a typosquat — you almost certainly intended a legitimately-named package. Remove checkout-checkout-test-block-aff, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.

I already installed checkout-checkout-test-block-aff — how do I know if it already compromised me?

If checkout-checkout-test-block-aff 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.

Is checkout-checkout-test-block-aff part of a known attack campaign?

Yes — checkout-checkout-test-block-aff is associated with the IN-MAL-2026-015220 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find checkout-checkout-test-block-aff across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for checkout-checkout-test-block-aff (version 35.9.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging checkout-checkout-test-block-aff across your stack and pipelines.

Malicious package

checkout-checkout-test-block-affnpm

checkout-checkout-test-block-aff is a confirmed malicious npm package (MAL-2026-12547) that typosquats a legitimate package to trick installs (malicious version 35.9.6). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in checkout-checkout-test-block-aff (npm)

MAL-2026-12547

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall checkout-checkout-test-block-aff

What this malware does

On require of the main entry, index.js loads loader.js which downloads a platform-specific executable from hardcoded Cloudflare Workers hosts (oob-worker.cf101-adf.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev), with a DNS TXT record fallback channel using sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru. The destination hosts are reassembled via array-join (e.g. ['oob-worker.cf','101-adf.worke','rs.dev'].join('')) to evade static string scanners. The downloaded payload is written to /var/tmp or %TEMP% under a disguised name (.cache<hex> on Unix, dotnet_diag_<hex>.exe on Windows to impersonate a Microsoft diagnostic tool), chmodded 0755, and spawned detached via cp.spawn('/bin/sh', ['-c', fp+' &'], {detached:true}) or cmd. No hash or signature verification is performed despite a cover-story comment claiming a SHA-256 integrity check; a dedup lockfile at /tmp/.analytics_state gates re-execution. lib/telemetry.js (81 KB, framed as an 'Analytics SDK') replicates the same fetch->base64-decode->write->chmod+x->spawn shell chain, importing child_process via string concatenation (require('child_'+'process')) to further hide the primitive. Installing or requiring this package yields arbitrary remote code execution on the installer's host from attacker-controlled infrastructure.

Malicious versions

1 flagged

35.9.6

Indicators of compromise (SHA-256)

ae29db4ecd6fc6c7250d5b388eb957c9b0d1ec2b8a8966928c3da7c31aa4bf87

Detection & response playbook

Typosquat

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for checkout-checkout-test-block-aff (version 35.9.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging checkout-checkout-test-block-aff across your stack and pipelines.
If you installed it — respond
checkout-checkout-test-block-aff is a typosquat — you almost certainly intended a legitimately-named package. Remove checkout-checkout-test-block-aff, 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 checkout-checkout-test-block-aff 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 checkout-checkout-test-block-aff 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

No. checkout-checkout-test-block-aff on npm has been identified as a malicious package (version 35.9.6 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015220

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks checkout-checkout-test-block-aff-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.

Malware detection Runtime egress monitoring

Explore

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