GHSA-mc52-mwq4-vfx3 knowns OS Command Injection via Insecure LSP Binary Path Config in .knowns/config.json

• npm knowns: < 0.30.0 → fixed in 0.30.0

Overview A critical Arbitrary Code Execution (ACE) vulnerability exists in the Knowns Language Server Protocol (LSP) detection and startup pipeline. The system blindly trusts the `settings.lsp.languages..binary` field defined in the project-level `.knowns/config.json` file. Because this field is never validated against an allowlist of managed binaries, and absolute paths are implicitly accepted, opening a malicious repository (or a legitimate repository where the config has been tampered with) results in the immediate execution of an attacker-controlled binary. The payload is executed twice per session: once during the initial `runVersionCheck` (health check), and again when the LSP server process is spawned via `Server.Start()`. When chained with the previously identified Config Overwrite vulnerabilities, this flaw yields a fully unauthenticated Remote Code Execution chain. Affected paths | File Path | Role | Vulnerability & Execution Impact | | :--- | :--- | :--- | | `internal/models/config.go` | Validation Gap | Missing Binary Validation (CWE-829): `ProjectSettings.Validate()` enforces duration formats for task lifecycles but completely ignores the `LSPLanguageSettings.Binary` field. Absolute paths, shell interpreters, and untrusted executables are silently accepted. | | `internal/lsp/detect.go` | Execution Sink #1 | Unsanitized Health Check Execution: `Detector.resolve()` passes the unvalidated override to `exec.LookPath()`, then invokes `runVersionCheck()` which blindly calls `cmd.Run()` on the attacker-controlled binary with `CheckArgs`. | | `internal/lsp/server.go` | Execution Sink #2 | Unsanitized LSP Server Spawn: `Server.Start()` passes the resolved binary path to `knownsprocess.Command()` and spawns it as a long-running background process via `cmd.Start()`, executing the payload a second time. | Root Cause Missing Validation in Configuration Schema In `internal/models/config.go`, the `ProjectSettings.Validate()` function is responsible for sanitizing the project configuration loaded from `.knowns/config.json`. However, it only validates task lifecycle durations: ```go func (s ProjectSettings) Validate() error { settings := s.EffectiveTaskLifecycle() if _, err := ParseTaskLifecycleDuration(settings.ArchiveAfter); err != nil { ... } // NO VALIDATION FOR s.LSP.Languages[lang].Binary return nil } ``` The `LSPLanguageSettings` struct exposes a `Binary` string field. When a malicious project is loaded, this string is passed unmodified into the LSP resolution pipeline. Blind Execution in LSP Detector In `internal/lsp/detect.go`, the `Detector.resolve()` function accepts an `override` string (from the config) and forces it into the execution pipeline: ```go func (d *Detector) resolve(ctx context.Context, root string, lang Language, override string) (ServerCommand, bool) { binaries := lang.Binaries if override != "" { binary := Binary{Name: override} // Attacker's malicious path injected here binaries = []Binary{binary} } for _, binary := range binaries { path, err := d.LookPath(binary.Name) // Accepts absolute paths (e.g., /tmp/evil.sh) // ... err = d.RunCheck(checkCtx, path, binary.CheckArgs...) // EXECUTION #1 // ... } } ``` `d.RunCheck` maps to `runVersionCheck`, which executes the binary via `knownsprocess.CommandContext(ctx, path, args...).Run()`. Unrestricted Process Spawn In `internal/lsp/server.go`, when the LSP manager starts the server, it executes the same compromised path: ```go func (s *Server) Start(ctx context.Context) error { // ... cmd := knownsprocess.Command(s.Command.Path, s.Command.Args...) // EXECUTION #2 cmd.Dir = s.Root // ... if err := cmd.Start(); err != nil { ... } } ``` Attack Vector | Phase | Request / Action | Effect | | :--- | :--- | :--- | | 1. Plant | Attacker commits `.knowns/config.json` containing `{"settings":{"lsp":{"languages":{"go":{"binary":"/tmp/evil.sh"}}}}}` to a repository. | Malicious config embedded in the project. | | 2. Trigger | Victim (or AI Agent) clones the repo and opens it with `knowns mcp` or `knowns browser`. | Auto-detection scans the project, finds a `.go` file, and loads the malicious config. | | 3. Execute (Health Check) | `Detector.resolve()` calls `runVersionCheck("/tmp/evil.sh", "version")`. | RCE Execution #1 occurs silently in the background. | | 4. Execute (LSP Spawn) | `Server.Start()` calls `cmd.Start()` with the same binary. | RCE Execution #2 occurs, spawning the malicious process as a long-running daemon. | Chained Attack Vector (Unauthenticated RCE): If combined with the Config Overwrite vulnerability (via `code.replace` path traversal), a remote attacker can overwrite `.knowns/config.json` in a target project, inject a payload, and trigger an LSP restart (via `docs.update` or server reload), achieving Remote Code Execution without any user interaction. Analysis This vulnerability is a textbook example of Inclusion of Functionality from Untrusted Control Sphere (CWE-829), commonly known in the IDE/Editor space as the "Malicious Workspace" vulnerability (similar to historical CVEs in VS Code where `.vscode/settings.json` could point to malicious interpreter paths). The core failure is the lack of a strict allowlist for executable paths. By relying on `exec.LookPath()`, the code allows an attacker to bypass binary name resolution simply by providing an absolute path (`/abs/path/evil.sh`) or a path containing a slash (`./evil.sh`). Furthermore, the execution happens automatically upon project load. In modern AI-driven development workflows, AI Agents automatically scan project files (like `.go`, `.ts`, `.py`) to provide context. The LSP detector triggers on file extensions, meaning the victim or agent does not even need to explicitly run a "build" or "start" command; the mere act of the Agent indexing the workspace triggers the payload. Fix *Patch is available right now at New Release.*