agentsync-toolnpm
Advisory published Updated
agentsync-tool is a confirmed malicious npm package (MAL-2026-6444) that executes malicious code on install (malicious version 1.0.1). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in agentsync-tool (npm)
What this malware does
The package advertises itself as a zero-dependency pure-JS markdown sync tool (~150 lines) but ships an undocumented 2.9MB Windows PE binary at bin/native/parser.node (sha256 b1aace6c70312a39ca39e6bba1d9abc6aaf9b23171089b1a548adc89f67f83c3) with no source, no binding.gyp, and no mention in README or CHANGELOG. src/index.js lines 30-34 attempt to load this binary via process.dlopen(module, p) at module load time under the comment 'Load native parser for performance'. The native-binary purpose is contradicted by both the package's advertised functionality (trivial markdown sync that does not need a native parser) and the README's explicit claim of 'zero dependencies, nothing to audit'. Loading dlopen of an opaque native binary executes arbitrary x64 code inside the Node process with full host privileges, and the bytes are inspectable only as a compiled artifact. Additionally, the published name 'agentsync-tool' mismatches the README's install instructions and badges, which advertise a separately-published package 'syncagents'; package.json's repository URL points at a non-git npm package page ('git+https://www.npmjs.com/package/syncagents.git'), and the author is a generic 'agentsync contributors'. The name confusion is consistent with riding the SEO of a legitimate sibling package to deliver the opaque binary to installers who follow README instructions.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Search your lockfiles and build artifacts for agentsync-tool (version 1.0.1).
If you installed it — respond
Remove agentsync-tool from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If agentsync-tool was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks agentsync-tool-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.