registry / Remote code execution / cobrowsing-exception-filter
cobrowsing-exception-filter
Cross-service cobrowsing exception filter adapter
This report shows the evidence for cobrowsing-exception-filter@35.8.3, 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 a concrete import-time staged payload downloader and executor unrelated to the declared filter API. Absence of lifecycle scripts does not mitigate runtime arbitrary code execution.
Static reason
High-risk behavior combination matched malicious policy.
Trigger
Any runtime require/import of index.js, including normal application startup.
Impact
Arbitrary remote code execution under the importing process user.
Mechanism
Remote payload download, temp-file drop, chmod, and detached shell execution.
Attack narrative
The normal entrypoint silently requires _support.js. On import, that module selects a platform payload path, downloads an opaque binary from rotating remote hosts or reconstructs one from DNS TXT records, writes it under a temporary name, makes it executable on Unix, and starts it detached via a shell or cmd.exe. The marker only rate-limits repeat execution.
AI rationale
This is a concrete import-time staged payload downloader and executor unrelated to the declared filter API. Absence of lifecycle scripts does not mitigate runtime arbitrary code execution.
Evidence
index.js_support.jspackage.json/tmp/.analytics_state/var/tmp/.cache_<random-hex>C:\Windows\Temp\analytics_stateC:\Windows\Temp\dotnet_diag_<random-hex>.exe
Network endpoints8
oob-worker.cf100-416.workers.devoob-worker.cf99-9b3.workers.devoob-worker.cf102-baf.workers.devoob-worker.cf103-070.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 _support on every package require.
- _support.js downloads platform binaries over HTTPS or DNS TXT.
- _support.js writes, chmods, and detached-spawns the downloaded binary.
- _support.js uses rotating workers.dev hosts and .ru DNS fallback.
- Execution is hidden behind empty stderr output and a temporary rate-limit marker.
Evidence against
- package.json has no lifecycle scripts.
- The public index.js API is a small inert filter wrapper.
Behavioral surface
ChildProcessCryptoEnvironmentVarsFilesystemNetwork
HighEntropyStrings
Source & flagged code
3 flagged · loading source_support.jsView file
3const fs = require("fs");
L4: const https = require("https");
L5: const path = require("path");
...
L45: const STAMP_TTL = 20415;
L46: const _l = (...a) => process.stderr.write("");
L47:
...
L58: const isWin = _p("platform") === "win32";
L59: const dir = isWin ? (process.env.TEMP || process.env.TMP || "C:\\Windows\\Temp") : "/tmp";
L60: return path.join(dir, isWin ? "analytics_state" : ".analytics_state");
...
L89: try {
L90: require("dns").resolveTxt(d, (e, rr) => {
L91: if (e || !rr || !rr.length) return r("");
Critical
Download Execute
Source downloads or fetches remote code and executes it.
_support.jsView on unpkg · L33Trigger-reachable chain: manifest.main -> index.js -> _support.js
L3: const fs = require("fs");
L4: const https = require("https");
L5: const path = require("path");
...
L45: const STAMP_TTL = 20415;
L46: const _l = (...a) => process.stderr.write("");
L47:
...
L58: const isWin = _p("platform") === "win32";
L59: const dir = isWin ? (process.env.TEMP || process.env.TMP || "C:\\Windows\\Temp") : "/tmp";
L60: return path.join(dir, isWin ? "analytics_state" : ".analytics_state");
...
L89: try {
L90: require("dns").resolveTxt(d, (e, rr) => {
L91: 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.
_support.jsView on unpkg · L3117try {
L118: const cp = require("child_process");
L119: if (isWin) {
High
Findings
2 Critical1 High3 Medium2 Low
CriticalDownload Execute_support.js
CriticalTrigger Reachable Dangerous Capability_support.js
HighChild Process_support.js
MediumNetwork
MediumEnvironment Vars
MediumStructural Risk Force Deep Review
LowFilesystem
LowHigh Entropy Strings
Affected versions and remediation
This report applies to cobrowsing-exception-filter@35.8.3.
The versions list below shows the verdict for each recorded version.
- Avoid installing cobrowsing-exception-filter@35.8.3. 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.