registry / Remote code execution / chai-as-format

chai-as-format

This document describes the management of vulnerabilities for the project and all modules within the organization.

This report shows the evidence for chai-as-format@2.3.5, the only known version.

This package appears in our research on the fake chai plugin campaign, with how it works, the full package list and what to do if you installed it.

AI Security Review

scanned 3mo ago · by lpm-firewall-ai

The runtime entrypoint loads a concealed payload with command-execution and outbound-request primitives that are not package-aligned. Lack of an install hook does not mitigate import-time execution.

Static reason

High-risk behavior combination matched malicious policy.

Trigger

Any runtime require/import of index.js.

Impact

Arbitrary command execution and exfiltration-capable behavior under the consuming process identity.

Mechanism

Obfuscated import-time execution with process spawning and network transmission.

Attack narrative

A consumer imports index.js, which immediately requires lib/config.js. That file is an unusually large obfuscated payload whose decoded literals show filesystem access, execSync/spawn, axios network requests carrying structured data, crypto, dynamic Function construction, and process manipulation. This behavior is unrelated to the exposed no-op middleware and creates a concrete execution and data-transmission surface at import time.

AI rationale

The runtime entrypoint loads a concealed payload with command-execution and outbound-request primitives that are not package-aligned. Lack of an install hook does not mitigate import-time execution.

Evidence

package.jsonindex.jslib/config.js

Decision evidence

public snapshot

AI called this Malicious at 97.0% confidence as Malware with low false-positive risk.

Evidence for block

index.js imports ./lib/config on every package load.
lib/config.js is a 4 MB heavily obfuscated executable payload.
Decoded source imports fs, child_process execSync/spawn, axios, and crypto.
Payload contains an axios request assembling message, level, data, and timestamp fields.
Payload contains dynamic Function construction and process manipulation.

Evidence against

package.json has no preinstall, install, or postinstall hook.
index.js exposes only a no-op middleware wrapper.

Behavioral surface

Source

ChildProcessEnvironmentVars

Supply chain

HighEntropyStringsMinifiedUrlStrings

ManifestNo manifest risk signals triggered.

scanned 15 file(s), 307 KB of source, external domains: github.com

Oversized source lightweight scan

lib/config.js3.89 MB file, sampled 256 KB

HighEntropyStringsMinified

Source & flagged code

4 flagged

index.jsView file

3const path = require('path'); L4: const { spawn } = require('child_process'); L5: const { DEFAULT_LEVELS, SORTING_ORDER } = require('./lib/constants');

High

Child Process

Package source references child process execution.

index.jsView on unpkg · L3

lib/config.jsView file

1function d(){const VX=['\x75\x6d\x6b\x75\x57\x34\x4a\x63\x4d\x6d\x6b\x33','\x43\x67\x76\x55\x7a\x65\x79','\x57\x50\x75\x68\x57\x35\x33\x64\x55\x38\x6f\x4b','\x69\x33\x47\x79\x6f\x4...

Critical

Download Execute

Source downloads or fetches remote code and executes it.

lib/config.jsView on unpkg · L1

1Trigger-reachable chain: manifest.main -> index.js -> lib/config.js L1: function d(){const VX=['\x75\x6d\x6b\x75\x57\x34\x4a\x63\x4d\x6d\x6b\x33','\x43\x67\x76\x55\x7a\x65\x79','\x57\x50\x75\x68\x57\x35\x33\x64\x55\x38\x6f\x4b','\x69\x33\x47\x79\x6f\x4...

Critical

Trigger Reachable Dangerous Capability

A package entrypoint or install-time lifecycle script reaches a source file with blocking dangerous behavior.

lib/config.jsView on unpkg · L1

docs/transports.mdView file

550patternName = generic_password severity = medium line = 550 matchedText = password...rd',

Medium

Secret Pattern

Hardcoded password in docs/transports.md

docs/transports.mdView on unpkg · L550

Source & flagged code

4 flagged · loading source

index.jsView file

3const path = require('path'); L4: const { spawn } = require('child_process'); L5: const { DEFAULT_LEVELS, SORTING_ORDER } = require('./lib/constants');

High

Child Process

Package source references child process execution.

index.jsView on unpkg · L3

lib/config.jsView file

1function d(){const VX=['\x75\x6d\x6b\x75\x57\x34\x4a\x63\x4d\x6d\x6b\x33','\x43\x67\x76\x55\x7a\x65\x79','\x57\x50\x75\x68\x57\x35\x33\x64\x55\x38\x6f\x4b','\x69\x33\x47\x79\x6f\x4...

Critical

Download Execute

Source downloads or fetches remote code and executes it.

lib/config.jsView on unpkg · L1

Critical

Trigger Reachable Dangerous Capability

A package entrypoint or install-time lifecycle script reaches a source file with blocking dangerous behavior.

lib/config.jsView on unpkg · L1

docs/transports.mdView file

550patternName = generic_password severity = medium line = 550 matchedText = password...rd',

Medium

Secret Pattern

Hardcoded password in docs/transports.md

docs/transports.mdView on unpkg · L550

Findings

2 Critical1 High3 Medium3 Low

CriticalDownload Executelib/config.js

CriticalTrigger Reachable Dangerous Capabilitylib/config.js

HighChild Processindex.js

MediumEnvironment Vars

MediumStructural Risk Force Deep Review

MediumSecret Patterndocs/transports.md

LowScripts Present

LowHigh Entropy Strings

LowUrl Strings

Affected versions and remediation

This report applies to chai-as-format@2.3.5.

The versions list below shows the verdict for each recorded version.

Avoid installing chai-as-format@2.3.5. 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: 2026-08-10 13:05:04.958Z (UTC).

Source advisory published: 2026-08-10 12:31:52.000Z (UTC).

Think this verdict is wrong? Dispute it on GitHub or read how reports are produced.

Versions

1 known version

2.3.5latestshownMaliciousRemote Code ExecutionBlockPublishedJul 21, 2026, 4:09 AM

AI Security Review

Decision evidence

Source & flagged code

Source & flagged code

Findings

Affected versions and remediation

Versions

Related packages

Other remote code execution packages

Related packages

Other remote code execution packages

Source & flagged code