MalwarePublished 9 Jul 2026Updated 1 Sep 2026

chai-as-modified (npm) · Malicious Code

Affects chai-as-modifiedSource GCVE Database

Malicious package : remove chai-as-modified and rotate any secrets on hosts that installed it.

Data as of 12 Sep 2026, 19:16 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-10043

What to do

Remove chai-as-modified from every project, lockfile and image that pulls it in. Treat any host that installed it as compromised: rotate the credentials, tokens and keys it could read, from a clean machine.

Affected software

Product	Affected	Fixed in
npmchai-as-modified	Affected =6.0.4	Fixed in–

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Description

The npm package 'chai-as-modified' is a malicious variant of the legitimate 'chai-as-promised' plugin. It attempts to execute out-of-band code by spawning a detached Node.js subprocess running a hidden script, which is not related to its advertised functionality. The package includes decoy content copied from an unrelated project to mislead users. The actual payload script is missing in the current version, causing the subprocess to error out, suggesting a possible staged or subsequent payload delivery. This behavior poses a high risk due to covert execution capabilities.

Impact

If the missing payload were present, the detached subprocess could execute arbitrary code independently of the parent process, potentially leading to unauthorized actions on the host system. The current version's missing payload causes errors, so no active exploitation is possible at this time. However, the presence of this mechanism indicates a high risk of covert malicious activity if the payload is delivered later.

Defensive guidance

Users should avoid installing or using 'chai-as-modified' version 6.0.4. Since the package is malicious and not a legitimate plugin, the best mitigation is to remove it from projects and replace it with the authentic 'chai-as-promised' package. Monitor package sources carefully to avoid similarly named malicious variants.

Summary

The 'chai-as-modified' npm package masquerades as a variant of the popular 'chai-as-promised' plugin but contains malicious code. Its exported function, intended for use with 'chai.use(...)', launches a detached and unreferenced Node.js subprocess executing a sibling script ('./lib/initializeCaller.js'). This subprocess runs independently of the parent process, creating an out-of-band execution channel unrelated to the package's stated purpose. The package also includes decoy source files copied from the 'pino' project and a README copied from 'pinojs/pino' to disguise its true intent. The referenced payload script is absent in the current tarball, causing the subprocess to fail, which may indicate a staged attack or payload delivery through subsequent updates.

References

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What to do

Affected software

Description

AI analysisMachine-generated, updated 12 Sep 2026, 19:16 UTC

Technical details

References

Community reviews