Which versions of num-format-helper are malicious?

The following npm versions of num-format-helper are flagged malicious: 1.0.0. Treat any of these as compromised.

How do I remediate num-format-helper if I installed it?

num-format-helper is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.

I already installed num-format-helper — how do I know if it already compromised me?

If num-format-helper 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 num-format-helper part of a known attack campaign?

Yes — num-format-helper is associated with the IN-MAL-2026-011065 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 num-format-helper 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 num-format-helper (version 1.0.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging num-format-helper across your stack and pipelines.

Malicious package

num-format-helpernpm

num-format-helper is a confirmed malicious npm package (MAL-2026-11107) that steals credentials and exfiltrates sensitive data (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in num-format-helper (npm)

MAL-2026-11107

Immediate action

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

npm uninstall num-format-helper

What this malware does

Package advertises itself as a number/locale formatting helper but its postinstall.js runs automatically on npm install and shells out via child_process/exec to collect host identity (hostname, user, id, sudo, uname), GitHub Actions variables including GITHUB_TOKEN and GITHUB_REPOSITORY, a broad env dump filtered by a credential regex (KEY|TOKEN|SECRET|CREDENTIAL|KUBE|JENKINS|NPM|GEM|CARGO|AZURE|GCP|AWS_|GH_TOKEN|GITHUB_TOKEN), network interfaces, running processes, and cloud instance metadata (AWS 169.254.169.254, Aliyun 100.100.100.200, Tencent). The collected data is base64-encoded and sent via curl in a GET request to the hardcoded Burp Collaborator subdomain pzs5w7ntzhsnepwk564lyfdci3oucl0a.oastify.com. The shipped index.js is a trivial unrelated stub, confirming the package is a cover story for the install-time exfiltration payload.

The OpenSSF Package Analysis project identified 'num-format-helper' @ 1.0.0 (npm) as malicious.

It is considered malicious because:

The package communicates with a domain associated with malicious activity.
The package executes one or more commands associated with malicious behavior.

Malicious versions

1 flagged

1.0.0

Indicators of compromise (SHA-256)

8a8aaefbf5f2df138b5dd99eeb8aa0247ffe7570759470e6ad7479fc0700345f

04a0ecb436de3a0e93a577a3ba1733b227bd536e02acf371df530c6a320e1001

Detection & response playbook

Credential / info stealer

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for num-format-helper (version 1.0.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging num-format-helper across your stack and pipelines.
If you installed it — respond
num-format-helper is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If num-format-helper 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 num-format-helper 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. num-format-helper on npm has been identified as a malicious package (version 1.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-011065

References

npmjs.com

Credits

Amazon Inspector · finder
OpenSSF: Package Analysis · finder

Detect & block this

O3 blocks num-format-helper-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring

Explore

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