🛡️ Sentinel: Secure Electron IPC handlers against injection

.jules/sentinel.md

@@ -0,0 +1,4 @@
+## 2026-07-17 - [IPC Command and Process Injection Prevention in Electron]
+**Vulnerability:** Unsanitized parameters exposed via IPC handlers in Electron allowed the renderer process to trigger arbitrary process execution (`restart-shell` with arbitrary executable path) and git command/argument injection (`git-cmd` with custom arguments like `--ext-diff`).
+**Learning:** Even if context isolation is enabled and the renderer does not expose the raw `child_process` module, exposed high-level IPC handlers (like Git commands or custom shell selection handlers) can still be abused as a bridge for command/argument injection if they do not strictly sanitize or validate their inputs on the main process side.
+**Prevention:** Always validate all parameters received from the IPC renderer on the main process side (the secure side). Restrict shell execution to a strict whitelist of known/safe shell binaries, and block dangerous git flags such as `--ext-diff`, `--textconv`, `--exec-path`, `--output`, `--pager`, `--config`, and short flags like `-c`/`-C`.

electron.cjs

@@ -647,8 +647,44 @@ ipcMain.handle('is-pty', () => {
   return usingPty;
 });
 
+const ALLOWED_SHELLS = [
+  'powershell.exe',
+  'pwsh.exe',
+  'cmd.exe',
+  'powershell',
+  'pwsh',
+  'cmd',
+  '/bin/bash',
+  '/bin/zsh',
+  '/bin/sh',
+  '/usr/bin/bash',
+  '/usr/bin/zsh',
+  '/usr/bin/sh',
+  'bash',
+  'zsh',
+  'sh',
+  'c:/windows/system32/cmd.exe',
+  'c:/windows/system32/windowspowershell/v1.0/powershell.exe',
+  'c:/windows/syswow64/cmd.exe',
+  'c:/windows/syswow64/windowspowershell/v1.0/powershell.exe'
+];
+
+function isSafeShell(shellPath) {
+  if (typeof shellPath !== 'string') return false;
+  const normalized = shellPath.trim().replace(/\\/g, '/').toLowerCase();
+  if (normalized.includes('/')) {
+    return ALLOWED_SHELLS.includes(normalized);
+  }
+  return ALLOWED_SHELLS.includes(normalized);
+}
+
 ipcMain.handle('restart-shell', (event, shellPath) => {
   if (shellPath) {
+    // Secure validation to prevent process execution of arbitrary binaries (Command/Process Injection vulnerability)
+    if (!isSafeShell(shellPath)) {
+      console.warn(`Blocked unsafe shell override attempt: "${shellPath}"`);
+      return false;
+    }
     // Override the shell for this restart
     const savedShell = workspaceRoot;
     workspaceRoot = savedShell;
@@ -721,6 +757,34 @@ ipcMain.handle('git-cmd', (event, cmdArgs) => {
       resolve({ success: false, stdout: '', stderr: `Blocked: '${subCmd}' is not allowed` });
       return;
     }
+
+    // Check for dangerous options to prevent git argument injection
+    const dangerousPatterns = [
+      '--ext-diff',
+      '--textconv',
+      '--exec-path',
+      '--output',
+      '--pager',
+      '--upload-pack',
+      '--receive-pack',
+      '--config',
+      '--git-dir',
+      '--work-tree'
+    ];
+
+    for (const part of parts) {
+      const lowerPart = part.toLowerCase();
+      // Block exact short option matches that are dangerous (covers -c and -C case-insensitively)
+      if (lowerPart === '-c') {
+        resolve({ success: false, stdout: '', stderr: `Blocked: Dangerous option '${part}' is not allowed` });
+        return;
+      }
+      // Block any argument containing a dangerous pattern
+      if (dangerousPatterns.some(pattern => lowerPart.includes(pattern))) {
+        resolve({ success: false, stdout: '', stderr: `Blocked: Dangerous option '${part}' is not allowed` });
+        return;
+      }
+    }
 
     // For commit, extract message without shell quoting artifacts
     if (subCmd === 'commit') {