Which versions of string-formatter-pro are malicious?

The following npm versions of string-formatter-pro are flagged malicious: 1.0.0, 1.0.1. Treat any of these as compromised.

How do I remediate string-formatter-pro if I installed it?

string-formatter-pro 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 string-formatter-pro — how do I know if it already compromised me?

If string-formatter-pro 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 string-formatter-pro part of a known attack campaign?

Yes — string-formatter-pro is associated with the IN-MAL-2026-010692, IN-MAL-2026-010722 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 string-formatter-pro 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 string-formatter-pro (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging string-formatter-pro across your stack and pipelines.

Malicious package

string-formatter-pronpm

Malicious code in string-formatter-pro (npm) Remove it immediately and rotate any exposed credentials.

MAL-2026-10748

Immediate action

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

npm uninstall string-formatter-pro

What this malware does

The package advertises itself as a string-formatting utility whose main module exports only a trivial one-line capitalize() function, but ships a postinstall.js lifecycle script that runs automatically on npm install. postinstall.js issues a chain of curl commands against cloud instance-metadata endpoints (AWS IMDS at 169.254.169.254, Alibaba at 100.100.100.200, Tencent at metadata.tencentyun.com, and 169.254.0.23) to harvest IAM security credentials, EC2 user-data, the instance identity document, and the host's OpenSSH public key, then POSTs the aggregated output plus a directory listing of /data/ to the hardcoded destination pwpzhsrbtvmfqrqr7onqcwnrcii960up.oastify.com (a Burp Collaborator subdomain). The trivial library surface is a decoy for install-time credential theft against the installer's cloud environment.

Malicious versions

2 flagged

1.0.01.0.1

Indicators of compromise (SHA-256)

966ebbfb039acea9e1f98c5f74f13e2aab1617e371719bc9543315702dbd67cd

dcc99e6af3349c947820bca0200bd761575b5fb45b03eb35e465b6bd9697976c

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 string-formatter-pro (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging string-formatter-pro across your stack and pipelines.
If you installed it — respond
string-formatter-pro 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 string-formatter-pro 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 string-formatter-pro 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. string-formatter-pro on npm has been identified as a malicious package (versions 1.0.0, 1.0.1 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-010692IN-MAL-2026-010722

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks string-formatter-pro-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