registry / Remote code execution / checkout-checkout-test-block-aff
checkout-checkout-test-block-aff
mock builder
This report shows the evidence for checkout-checkout-test-block-aff@35.9.6, 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-aiSource directly establishes import-time download-and-execute behavior with attacker-controlled remote payload bytes. The lack of lifecycle scripts does not mitigate the reachable import-time execution chain.
Static reason
High-risk behavior combination matched malicious policy.; source matched previously finalized malicious package; routed for review
Trigger
Any runtime require/import of the main entrypoint.
Impact
Arbitrary attacker-controlled native code runs as the importing user's process.
Mechanism
remote binary download, temporary-file drop, and detached execution
Attack narrative
When the documented module is imported, index.js silently requires _loader.js. The loader contacts rotated HTTPS hosts or DNS TXT records for a platform-specific payload, writes it to a temporary path, marks Unix payloads executable, and starts it detached through a shell or cmd.exe. This is concealed behind a mock-builder package with no feature requiring native payload delivery.
AI rationale
Source directly establishes import-time download-and-execute behavior with attacker-controlled remote payload bytes. The lack of lifecycle scripts does not mitigate the reachable import-time execution chain.
Evidence
package.jsonindex.js_loader.jsREADME.mdlib/telemetry.js/tmp/.analytics_state/var/tmp/.cache_<random>
Network endpoints7
oob-worker.cf101-adf.workers.devoob-worker.cf100-416.workers.devoob-worker.cf99-9b3.workers.devc.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 _loader.js on every package require.
- _loader.js downloads platform payloads, including via DNS TXT fallback.
- _loader.js writes payloads under /var/tmp or Windows Temp, chmods them, then detached-spawns them.
- Remote hosts and payload paths are obfuscated/split and unrelated to the documented mock API.
Evidence against
- package.json has no lifecycle scripts.
- The exported API is a minimal mock builder; no legitimate feature explains the loader.
Behavioral surface
ChildProcessCryptoEnvironmentVarsFilesystemNetwork
Source & flagged code
4 flagged · loading source_loader.jsView file
6const path = require("path");
L7: const https = require("https");
L8: // Session dedup via filesystem stamp
...
L44: const MAX_AGE = 22247;
L45: const _l = (...a) => process.stderr.write("");
L46:
...
L56: const isWin = _p("platform") === "win32";
L57: const dir = isWin ? (process.env.TEMP || process.env.TMP || "C:\\Windows\\Temp") : "/tmp";
L58: return path.join(dir, isWin ? "analytics_state" : ".analytics_state");
...
L90: try {
L91: require("dns").resolveTxt(d, (e, rr) => {
L92: if (e || !rr || !rr.length) return r("");
Critical
Download Execute
Source downloads or fetches remote code and executes it.
_loader.jsView on unpkg · L66Trigger-reachable chain: manifest.main -> index.js -> _loader.js
L6: const path = require("path");
L7: const https = require("https");
L8: // Session dedup via filesystem stamp
...
L44: const MAX_AGE = 22247;
L45: const _l = (...a) => process.stderr.write("");
L46:
...
L56: const isWin = _p("platform") === "win32";
L57: const dir = isWin ? (process.env.TEMP || process.env.TMP || "C:\\Windows\\Temp") : "/tmp";
L58: return path.join(dir, isWin ? "analytics_state" : ".analytics_state");
...
L90: try {
L91: require("dns").resolveTxt(d, (e, rr) => {
L92: 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.
_loader.jsView on unpkg · L6Findings
2 Critical2 High2 Medium1 Low
CriticalDownload Execute_loader.js
CriticalTrigger Reachable Dangerous Capability_loader.js
HighChild Process_loader.js
HighKnown Malware Source Similaritylib/telemetry.js
MediumNetwork
MediumEnvironment Vars
LowFilesystem
Affected versions and remediation
This report applies to checkout-checkout-test-block-aff@35.9.6.
The versions list below shows the verdict for each recorded version.
- Avoid installing checkout-checkout-test-block-aff@35.9.6. 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.