assertcore
This report shows the evidence for assertcore@3.1.7. 1 of 2 known versions is blocked or flagged. The newest version, 0.0.1-security, is allowed. See all versions.
OpenSSF/OSV Malicious Advisory
imported 4mo ago · by OpenSSF/OSVOpenSSF/OSV advisory MAL-2026-6365 confirms this npm version as malicious.
Advisory
MAL-2026-6365
Source
OpenSSF Malicious Packages via OSV
Summary
Malicious code in assertcore (npm)
Details
Package `assertcore` impersonates the popular `chai` assertion library (ships a copy of chai source as cover; author and homepage differ from the genuine project). On `require('assertcore')` / `import 'assertcore'`, `index.js` spawns a detached `node` subprocess running `lib/chai/utils/addAssertion.js` with stdio set to ignore: `const chaiBinding = spawn("node", [addAssertion, JSON.stringify(args)], {detached: true, stdio: "ignore"})`. The spawned script is heavily obfuscated using obfuscator.io string-array rotation, a base64-with-substitution decoder, and hex-arithmetic indexing to hide that it `require`s http(s), performs a GET to a URL assembled from obfuscated literals, and passes the response body into `new Function('require', body)(require)` — executing attacker-supplied JavaScript with full Node privileges on every install or require. The combination of name impersonation, chai-source cover, detached/silenced subprocess, obfuscated network destination, and import-time fetch-and-eval is an unambiguous supply-chain attack on installers.
## Source: ghsa-malware (4b9c1b24c21140b120efceeccb9ced05c56a580dca792d07c43cffa1e24d7ca8) 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.
References
Source & flagged code
0 flagged · loading sourceNo flagged code excerpts are attached to this scan.
Findings
1 High
HighOsv Malicious Advisory
Affected versions and remediation
This report applies to assertcore@3.1.7.
The versions list below shows the verdict for each recorded version.
- Avoid installing assertcore@3.1.7. Remove it from direct dependencies and check your lockfile for transitive copies.
- Choose an independently verified alternative or release. This report does not establish that other versions are safe.
- If this version ran, investigate the affected machine and build environment. Rotate credentials it could access and rebuild from a trusted environment.
Evidence last updated: .
Source advisory published: .
This report uses published external intelligence. The advisory does not provide a separate source-code analysis for each listed version.
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