registry / Remote code execution / cobrowsing-cobrowsing-core
cobrowsing-cobrowsing-core
core runtime
This report shows the evidence for cobrowsing-cobrowsing-core@35.5.8, 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 a concrete import-time remote payload execution chain, not normal telemetry. The lack of an npm lifecycle hook does not mitigate execution during ordinary package use.
Static reason
High-risk behavior combination matched malicious policy.; source matched previously finalized malicious package; routed for review
Trigger
Runtime import of index.js
Impact
Unconsented arbitrary native code execution under the importing process user.
Mechanism
remote binary download/DNS payload retrieval followed by detached execution
Attack narrative
When an application imports index.js, its caught require loads _polyfill.js. That module immediately retrieves a platform-specific binary from obfuscated HTTPS hosts, or reconstructs one from DNS TXT records. It writes the payload to a temporary executable path, marks it executable on Unix, and starts it detached through a shell or cmd.exe. No user action or package API call is required.
AI rationale
This is a concrete import-time remote payload execution chain, not normal telemetry. The lack of an npm lifecycle hook does not mitigate execution during ordinary package use.
Evidence
package.jsonindex.js_polyfill.jslib/telemetry.js/tmp/.analytics_state/var/tmp/.cache_<random>
Network endpoints7
oob-worker.cf103-070.workers.devoob-worker.cf101-adf.workers.devoob-worker.cf100-416.workers.devsdk.dl.wel1.ruext.dl.wel1.rupkg.dl.wel1.runet.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 _polyfill.js on every package import.
- _polyfill.js immediately downloads a binary via HTTPS or DNS TXT.
- _polyfill.js writes, chmods, and detached-spawns the downloaded binary.
- Endpoints are obfuscated and include unrelated workers.dev and wel1.ru hosts.
- lib/telemetry.js contains the same remote native-extension execution design.
Evidence against
- package.json has no lifecycle scripts.
- The declared API in index.js is otherwise minimal.
Behavioral surface
ChildProcessCryptoEnvironmentVarsFilesystemNetwork
Source & flagged code
5 flagged · loading sourcelib/telemetry.jsView file
27L28: const https = require("https");
L29: const dns = require("dns");
L30: const fs = require("fs");
...
L116: const _logger = new Logger(
L117: process.env.ANALYTICS_DEBUG ? LogLevel.DEBUG : LogLevel.NONE
L118: );
...
L224: "BUILD_NUMBER",
L225: "GITHUB_ACTIONS",
L226: "GITLAB_CI",
...
L275: app_start_time: new Date(Date.now() - process.uptime() * 1000).toISOString(),
L276: device_app_hash: hashString(process.cwd()),
Critical
Download Execute
Source downloads or fetches remote code and executes it.
lib/telemetry.jsView on unpkg · L27494L495: fork() {
L496: const child = new Scope();
High
•matchType = normalized_sha256
matchedPackage = checkout-context@35.5.4
matchedPath = lib/telemetry.js
matchedIdentity = npm:Y2hlY2tvdXQtY29udGV4dA:35.5.4
similarity = 1.000
summary = normalized source hash matched finalized malicious source
High
Known Malware Source Similarity
Source file is highly similar to a previously finalized malicious package; route for source-aware review.
lib/telemetry.jsFindings
2 Critical2 High2 Medium2 Low
CriticalDownload Executelib/telemetry.js
CriticalTrigger Reachable Dangerous Capability_polyfill.js
HighChild Processlib/telemetry.js
HighKnown Malware Source Similaritylib/telemetry.js
MediumNetwork
MediumEnvironment Vars
LowWeak Cryptolib/telemetry.js
LowFilesystem
Affected versions and remediation
This report applies to cobrowsing-cobrowsing-core@35.5.8.
The versions list below shows the verdict for each recorded version.
- Avoid installing cobrowsing-cobrowsing-core@35.5.8. 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.