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IDE Extension Threat Patterns

Detection categories used by scanners/ide-extension-scanner.mjs (prefix IDE). Based on Koi Security / ExtensionTotal research 2024-2026 and VS Code / JetBrains official documentation.

Research brief: /Users/ktg/.claude/plans/research-ide-extension-prescan.md.

Scope

VS Code + forks (Cursor, Windsurf, VSCodium, code-server, Insiders, Remote-SSH) and JetBrains/IntelliJ plugins (IntelliJ IDEA, PyCharm, WebStorm, GoLand, Rider, CLion, PhpStorm, RubyMine, DataGrip, DataSpell, RustRover, Aqua, Gateway, and Android Studio). JetBrains discovery shipped in v6.6.0.

1. Blocklist Match (CRITICAL)

Signal: Extension ID (lowercased publisher.name) matches entry in knowledge/top-vscode-extensions.json blocklist array.

Case: TigerJack (11 malicious extensions, 17K+ installs). WhiteCobra (24 extensions, ~$500K crypto theft). VS Code Cryptojacking Campaign ("Mark H" impersonator, 1M+ installs). Known-malicious IDs are CRITICAL.

Format: publisher.name@version or publisher.name@* for any version.

OWASP: LLM03 (Supply Chain), ASI04.

2. Theme-with-Code (HIGH)

Signal: package.json categories includes "Themes" AND (main is truthy OR activationEvents non-empty).

Case: "A Wolf in Dark Mode" — the Material Theme malware. Popular theme with hidden malware under color-scheme. Pure themes require zero runtime code; any main/activationEvents on a theme is a strong red flag.

OWASP: LLM06 (Excessive Agency), ASI02.

3. Sideload Signal (HIGH unsigned, MEDIUM signed)

Signal: extensions.json entry has metadata.source === "vsix" (i.e. installed from file, not Marketplace).

Rationale: Marketplace signature verification and malware-scan bypassed for .vsix-file installs. Legitimate use cases exist (private extensions, dev testing), but high malware-ratio in observed incidents.

Modifier: If .signature.p7s file present in extension root → downgrade to MEDIUM (possibly Marketplace-downloaded .vsix).

OWASP: LLM03.

4. Broad Activation Surface (MEDIUM / LOW)

Signal: package.json activationEvents includes "*" (MEDIUM) or "onStartupFinished" (LOW).

Rationale: "Wants to run always" is a strong capability signal — necessary for a few legitimate tools (shell integrators, system monitors) but unusual for most extensions. Exemption: exact-match against top-100 list.

Note: VS Code 1.74+ no longer requires activationEvents for declarative contributes — absence of events is NOT suspicious.

OWASP: LLM06.

5. Typosquat (HIGH / MEDIUM)

Signal: Extension ID has Levenshtein distance ≤ 2 from a top-100 extension ID, excluding exact match.

  • Distance 1 → HIGH
  • Distance 2 AND target is in top-50 → MEDIUM

Case: TigerJack aliases ab-498, 498, 498-00 targeting popular AI / utility extensions. Publisher impersonation (e.g. ms-pythom.pythom vs ms-python.python). AI-assistant typosquats (claude-code, codeium, cody).

OWASP: LLM03.

6. Extension Pack Expansion (MEDIUM)

Signal: package.json extensionPack array contains ≥ 3 bundled extension IDs.

Rationale: Extension packs amplify trust chain — installing one extension installs N others, each of which brings its own risk surface.

OWASP: LLM03.

7. Dangerous Uninstall Hook (HIGH / LOW)

Signal: package.json scripts["vscode:uninstall"] exists AND references one of: child_process, curl, wget, rm, powershell, iex, Invoke-Expression, Start-Process.

Rationale: Uninstall scripts are a persistence hook — attacker can delay destructive payload to trigger on uninstall attempt. VS Code runs these scripts with the user's privileges.

OWASP: LLM06, ASI02.

8. Data Exfiltration Patterns (delegated)

Detected by reused scanners on extension bundled source:

  • Hardcoded webhooks (Discord, Pipedream, webhook.site, Burp Collaborator, interactsh) → detected by NET scanner
  • Base64-encoded C2 domains → detected by ENT scanner
  • Unicode Tag steganography (GlassWorm pattern) → detected by UNI scanner
  • Env var exfiltration (process.env.HOME, SSH keys, .aws/credentials, .env) → detected by TNT scanner
  • Clipboard / screen capture misuse → detected by NET + TNT via API surface

Cases: GlassWorm (Unicode steganography + blockchain C2), MaliciousCorgi (AI-assistant data leaks), VS Code Cryptojacking (PowerShell download-and-execute), screen-capture malware ("Bitcoin Black", "Codo AI").

OWASP: LLM01 (Prompt Injection), LLM02 (Sensitive Disclosure), LLM03.

9. Nested npm Supply Chain (delegated)

Detected by SCR scanner on extension's bundled package-lock.json or flat package.json dependencies.

Rationale: A typical VS Code extension with main bundles 50–500+ transitive npm deps. VS Code Marketplace malware-scan does NOT inspect nested deps. Compromised npm packages (event-stream, rc, nx, ua-parser-js, lottie-player) flow into extensions automatically at build time.

OWASP: LLM03, ASI04.

10. Memory Poisoning via README / CHANGELOG (delegated)

Detected by MEM scanner on extension README.md and CHANGELOG.md.

Rationale: Extension README is displayed in VS Code when user inspects extension details. Prompt-injection payloads in README can poison co-located LLM assistants (Copilot, Claude Code) if the user asks about the extension.

OWASP: LLM01.

11. JetBrains Plugin Format (informational)

Layout: JetBrains plugins distribute as a ZIP or JAR. Installed plugins on disk are already extracted by the IDE (directory form). A sideloaded URL download is a single ZIP with layout <artifact>/lib/<main>.jar + lib/<dep>.jar. The authoritative manifest META-INF/plugin.xml lives inside the main JAR in lib/, not at the ZIP root. META-INF/MANIFEST.MF lives in each individual JAR.

Scanner strategy: walk lib/*.jar, open each as a nested ZIP, read plugin.xml from the first JAR that contains one, then parse MANIFEST.MF from every JAR for Premain-Class and coordinates (Implementation-Title, Bundle-SymbolicName).

Source: https://plugins.jetbrains.com/docs/intellij/plugin-content.html.

12. JetBrains Broad Activation (HIGH / MEDIUM)

Signals (ranked):

  • HIGH: <application-components> present (legacy, loads at IDE start, blocks dynamic reload) OR an AppLifecycleListener registered via <applicationListener topic="...AppLifecycleListener"/> with an appStarted handler. Equivalent to "run code at IDE startup."
  • MEDIUM: <postStartupActivity> or <backgroundPostStartupActivity> — runs once shortly after project open. Common in legitimate plugins but still a capability signal.
  • MEDIUM: applicationService with preload="true" — forces early instantiation at IDE load.

Case: CVE-2024-37051 (JetBrains GitHub integration, June 2024) exfiltrated GitHub access tokens via malicious pull request content — required no user interaction once opened, abusing startup-time hooks.

OWASP: LLM06 (Excessive Agency), ASI02.

13. Theme-with-Code (JetBrains) (HIGH)

Signal: plugin.xml declares <themeProvider> AND any of: applicationService, projectService, action, applicationListener, projectListener, postStartupActivity, <application-components>.

Rationale: A pure JetBrains theme (LAF — look-and-feel) needs only a themeProvider + a .theme.json resource. Bundling services/actions/listeners on a theme mirrors the VS Code "A Wolf in Dark Mode" pattern and is a strong red flag.

OWASP: LLM06, ASI02.

14. Java Agent — Premain-Class (HIGH)

Signal: Any JAR in lib/ has Premain-Class: <fqcn> in META-INF/MANIFEST.MF.

Rationale: Premain-Class registers a Java agent, giving bytecode-instrumentation authority over the IDE JVM (hook every class load, rewrite methods, intercept reflection). No legitimate third-party IntelliJ plugin needs this. If present together with Can-Redefine-Classes: true or Can-Retransform-Classes: true, severity is CRITICAL.

Reference: Log4Shell 2021 retrospective and subsequent JVM attacks highlight Premain-Class as a persistent instrumentation vector.

OWASP: LLM06, ASI04.

15. Native Binary Bundling (MEDIUM / HIGH)

Signal: .dll, .so, .dylib, .exe file inside any JAR in lib/ or in the plugin directory tree.

Rationale: Bundled native binaries escape JVM sandboxing and cannot be audited by JVM-level scanners. Legitimate uses exist (native filesystem watchers, DB drivers) but are rare — most plugins should be pure JVM bytecode. Severity is MEDIUM by default, HIGH when combined with Java-agent signal (#14) or broad activation (#12).

Case: OX Security 2025 research on JetBrains Marketplace demonstrated that signed plugins can still bundle arbitrary native payloads — the verified badge attests publisher identity, not plugin safety.

OWASP: LLM03, ASI04.

16. Legacy <application-components> (MEDIUM advisory)

Signal: plugin.xml uses the deprecated <application-components>, <project-components>, or <module-components> elements instead of modern <applicationService> / <extensions defaultExtensionNs="com.intellij">.

Rationale: Deprecated since 2020. Plugins that use components cannot be dynamically loaded/unloaded and force a restart on install, bypassing IDE-managed hot-reload safety. Often found together with other legacy red flags.

OWASP: LLM06.

17. Shaded/Uncoordinated JARs (MEDIUM)

Signal: JAR in lib/ has no recognisable coordinates (Implementation-Title, Bundle-SymbolicName, Implementation-Version absent from MANIFEST.MF) OR class files appear under shaded package prefixes (com.company.shaded.*, plugin.relocated.*).

Rationale: Uncoordinated or shaded JARs cannot be mapped to an OSV or Maven Central entry, so transitive-dependency auditing is impossible. YouTrack IJPL-212393 confirms JetBrains cannot reliably identify shaded library content either, so the signature-warning UI sometimes emits no warning at all.

OWASP: LLM03, ASI04.

Known Limitations

  • No runtime bytecode analysis — JARs are inspected as ZIPs and via MANIFEST.MF only. Method-level instrumentation detection is out of scope.
  • No VSIX extraction (pass extracted directory instead)
  • No Marketplace API lookups without --online flag (publisher age, download count, verified status unavailable offline)
  • Profile-specific extension filtering not implemented (all installed extensions are scanned)
  • .obsolete file parsing not implemented (extensions marked obsolete are still scanned — harmless but redundant)
  • Real-time IDE hooks are out of scope (separate repo, planned)

References