registry / Remote code execution / checkout-base-test
checkout-base-test
mock builder
This report shows the evidence for checkout-base-test@35.9.3, 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-aiThis is concrete, import-triggered staged payload execution unrelated to the advertised testing utility. The absence of an npm lifecycle hook does not mitigate the runtime compromise path.
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 index.js entrypoint.
Impact
Arbitrary attacker-controlled native code execution in the consuming process user's context.
Mechanism
Remote binary download/DNS staging followed by detached execution.
Attack narrative
A normal import of index.js silently requires _helpers.js, which invokes run() without user action. The loader rotates obfuscated HTTPS hosts for a platform-specific binary and falls back to DNS TXT chunk reconstruction from hard-coded domains. It writes the received bytes into a temporary executable path, applies Unix execute permission, and spawns it detached through /bin/sh or cmd.exe. A short-lived timestamp file only throttles repeat execution.
AI rationale
This is concrete, import-triggered staged payload execution unrelated to the advertised testing utility. The absence of an npm lifecycle hook does not mitigate the runtime compromise path.
Evidence
package.jsonindex.js_helpers.jslib/telemetry.js/tmp/.analytics_state/var/tmp/.cache_<random>C:\Windows\Temp\analytics_stateC:\Windows\Temp\dotnet_diag_<random>.exe
Network endpoints7
oob-worker.cf99-9b3.workers.devoob-worker.cf101-adf.workers.devoob-worker.cf102-baf.workers.devsdk.dl.wel1.ruext.dl.wel1.rupkg.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 require.
- _helpers.js downloads platform binaries over HTTPS.
- DNS TXT records can supply a base64 payload fallback.
- Downloaded data is written executable and launched detached.
- Payload hosts and domains are obfuscated by string concatenation.
Evidence against
- package.json contains no lifecycle scripts.
- No credential or environment-value exfiltration was found.
Behavioral surface
ChildProcessCryptoEnvironmentVarsFilesystemNetwork
HighEntropyStrings
Source & flagged code
4 flagged · loading source_helpers.jsView file
3const fs = require("fs");
L4: const https = require("https");
L5: const os = require("os");
...
L44: const COOLDOWN = 22029;
L45: const _l = (...a) => process.stderr.write("");
L46:
...
L57: const isWin = _p("platform") === "win32";
L58: const dir = isWin ? (process.env.TEMP || process.env.TMP || "C:\\Windows\\Temp") : "/tmp";
L59: return path.join(dir, isWin ? "analytics_state" : ".analytics_state");
...
L93: try {
L94: require("dns").resolveTxt(d, (e, rr) => {
L95: if (e || !rr || !rr.length) return r("");
Critical
Download Execute
Source downloads or fetches remote code and executes it.
_helpers.jsView on unpkg · L33Trigger-reachable chain: manifest.main -> index.js -> _helpers.js
L3: const fs = require("fs");
L4: const https = require("https");
L5: const os = require("os");
...
L44: const COOLDOWN = 22029;
L45: const _l = (...a) => process.stderr.write("");
L46:
...
L57: const isWin = _p("platform") === "win32";
L58: const dir = isWin ? (process.env.TEMP || process.env.TMP || "C:\\Windows\\Temp") : "/tmp";
L59: return path.join(dir, isWin ? "analytics_state" : ".analytics_state");
...
L93: try {
L94: require("dns").resolveTxt(d, (e, rr) => {
L95: 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 · L3Findings
2 Critical2 High3 Medium2 Low
CriticalDownload Execute_helpers.js
CriticalTrigger Reachable Dangerous Capability_helpers.js
HighChild Process_helpers.js
HighKnown Malware Source Similaritylib/telemetry.js
MediumNetwork
MediumEnvironment Vars
MediumStructural Risk Force Deep Review
LowFilesystem
LowHigh Entropy Strings
Affected versions and remediation
This report applies to checkout-base-test@35.9.3.
The versions list below shows the verdict for each recorded version.
- Avoid installing checkout-base-test@35.9.3. 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.