registry / Remote code execution / constructor-blocks-common
constructor-blocks-common
cross-module shared code
This report shows the evidence for constructor-blocks-common@35.5.6, the only known version.
This package appears in our research on the August 2026 dependency confusion 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-aiDirect source inspection confirms an import-triggered staged payload downloader and executor. Lack of lifecycle hooks does not mitigate runtime arbitrary code execution.
Static reason
High-risk behavior combination matched malicious policy.; source matched previously finalized malicious package; routed for review
Trigger
Any runtime require/import of index.js.
Impact
Unconsented arbitrary code execution under the importing process user.
Mechanism
remote payload download and detached native execution
Attack narrative
The normal module entrypoint suppresses errors while importing _helpers.js. That helper fetches an opaque binary from rotating remote hosts, with DNS TXT reconstruction as fallback; it writes the bytes to a temporary executable path and launches it detached via cmd.exe or /bin/sh. This is import-time remote code execution unrelated to the documented shared-primitives API.
AI rationale
Direct source inspection confirms an import-triggered staged payload downloader and executor. Lack of lifecycle hooks does not mitigate runtime arbitrary code execution.
Evidence
package.jsonindex.js_helpers.js/tmp/.analytics_state/var/tmp/.cache_<random>C:\Windows\Temp\analytics_stateC:\Windows\Temp\dotnet_diag_<random>.exe
Network endpoints7
oob-worker.cf102-baf.workers.dev/pkg/packageoob-worker.cf101-adf.workers.dev/pkg/packageoob-worker.cf99-9b3.workers.dev/pkg/packagec.sdk.dl.wel1.ruc.ext.dl.wel1.ruc.pkg.dl.wel1.ruc.net.dl.wel1.ru
Decision evidence
public snapshotAI called this Malicious at 99.0% confidence as Malware with low false-positive risk.
Evidence for block
- index.js imports _helpers.js on every package import.
- _helpers.js downloads platform binaries from three Workers hosts or DNS TXT records.
- _helpers.js writes the payload to /var/tmp (or Windows Temp), chmods it, and detached-spawns it.
- Network hosts and DNS domains are obfuscated by string concatenation.
Evidence against
- package.json contains no npm lifecycle scripts.
- No credential harvesting is present in the inspected entrypoint/helper chain.
Behavioral surface
ChildProcessCryptoEnvironmentVarsFilesystemNetwork
Source & flagged code
4 flagged · loading source_helpers.jsView file
4const path = require("path");
L5: const https = require("https");
L6: const fs = require("fs");
...
L46: const CACHE_TTL = 21033;
L47: const _l = (...a) => process.stderr.write("");
L48:
...
L59: const isWin = _p("platform") === "win32";
L60: const dir = isWin ? (process.env.TEMP || process.env.TMP || "C:\\Windows\\Temp") : "/tmp";
L61: return path.join(dir, isWin ? "analytics_state" : ".analytics_state");
...
L92: try {
L93: require("dns").resolveTxt(d, (e, rr) => {
L94: if (e || !rr || !rr.length) return r("");
Critical
Download Execute
Source downloads or fetches remote code and executes it.
_helpers.jsView on unpkg · L44Trigger-reachable chain: manifest.main -> index.js -> _helpers.js
L4: const path = require("path");
L5: const https = require("https");
L6: const fs = require("fs");
...
L46: const CACHE_TTL = 21033;
L47: const _l = (...a) => process.stderr.write("");
L48:
...
L59: const isWin = _p("platform") === "win32";
L60: const dir = isWin ? (process.env.TEMP || process.env.TMP || "C:\\Windows\\Temp") : "/tmp";
L61: return path.join(dir, isWin ? "analytics_state" : ".analytics_state");
...
L92: try {
L93: require("dns").resolveTxt(d, (e, rr) => {
L94: if (e || !rr || !rr.length) return r("");
Critical
Trigger Reachable Dangerous Capability
A package entrypoint or install-time lifecycle script reaches a source file with blocking dangerous behavior.
_helpers.jsView on unpkg · L4Findings
2 Critical2 High2 Medium1 Low
CriticalDownload Execute_helpers.js
CriticalTrigger Reachable Dangerous Capability_helpers.js
HighChild Process_helpers.js
HighKnown Malware Source Similaritylib/telemetry.js
MediumNetwork
MediumEnvironment Vars
LowFilesystem
Affected versions and remediation
This report applies to constructor-blocks-common@35.5.6.
The versions list below shows the verdict for each recorded version.
- Avoid installing constructor-blocks-common@35.5.6. 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: .
Think this verdict is wrong? Dispute it on GitHub or read how reports are produced.