Which versions of assert-kit are malicious?

The following npm versions of assert-kit are flagged malicious: 4.3.2. Treat any of these as compromised.

How do I remediate assert-kit if I installed it?

assert-kit establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

I already installed assert-kit — how do I know if it already compromised me?

If assert-kit 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.

Is assert-kit part of a known attack campaign?

Yes — assert-kit is associated with the GHSA-748x-3gxw-v7xv, IN-MAL-2026-007375 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 assert-kit across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for assert-kit (version 4.3.2).

Malicious package

assert-kitnpm

Advisory published Jun 19, 2026Updated Jun 23, 2026

assert-kit is a confirmed malicious npm package (MAL-2026-6200) that opens a backdoor for remote access (malicious version 4.3.2). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in assert-kit (npm)

MAL-2026-6200

Immediate action

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

npm uninstall assert-kit

What this malware does

[email protected] impersonates the chai assertion library (bundles chai's source, contributors, and API surface under a different author and homepage assertkit.com) and adds a remote-code execution backdoor. On require('assert-kit'), index.js calls validate_assert() at module top level, which spawns a detached node subprocess running lib/chai/utils/addAssertion.js with stdio:'ignore' and unref() so the child survives the consumer process. lib/chai/utils/addAssertion.js is heavily obfuscator.io-obfuscated; after string-array decoding it requires 'https', performs an https.get to a URL assembled from decoded strings, and passes the response body to new Function('require', body)(require) — running attacker-controlled JavaScript with full Node capabilities (filesystem, network, child_process, environment). Any project that installs and require()s this package executes whatever code the operator currently serves from the hardcoded endpoint, in a backgrounded process the user cannot easily see or terminate.

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.

Malicious versions

1 flagged

4.3.2

Indicators of compromise (SHA-256)

a42618d9b7dbd1c89448d216bbe53a557d2a1e95064936fcafe9ffece01c61a9

6e21fa9c37e9944a00f7e85c7476f8fd4dc6bcd1f8fcd064a90488ef93d5bd12

Detection & response playbook

Backdoor / remote access

Find it
Search your lockfiles and build artifacts for assert-kit (version 4.3.2).
If you installed it — respond
assert-kit establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If assert-kit 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

No. assert-kit on npm has been identified as a malicious package (version 4.3.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GHSA-748x-3gxw-v7xvIN-MAL-2026-007375

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks assert-kit-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database