Added warning to avoid command substitution in run_shell_command tool… (#9934)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

packages/core/src/tools/shell.ts

@@ -395,10 +395,18 @@ function getShellToolDescription(): string {
 }
 
 function getCommandDescription(): string {
+  const cmd_substitution_warning =
+    '\n*** WARNING: Command substitution using $(), `` ` ``, <(), or >() is not allowed for security reasons.';
   if (os.platform() === 'win32') {
-    return 'Exact command to execute as `cmd.exe /c <command>`';
+    return (
+      'Exact command to execute as `cmd.exe /c <command>`' +
+      cmd_substitution_warning
+    );
   } else {
-    return 'Exact bash command to execute as `bash -c <command>`';
+    return (
+      'Exact bash command to execute as `bash -c <command>`' +
+      cmd_substitution_warning
+    );
   }
 }
 

packages/core/src/utils/shell-utils.test.ts

@@ -145,6 +145,15 @@ describe('isCommandAllowed', () => {
       expect(result.reason).toContain('Command substitution');
     });
 
+    it('should block command substitution using `>(...)`', () => {
+      const result = isCommandAllowed(
+        'echo "Log message" > >(tee log.txt)',
+        config,
+      );
+      expect(result.allowed).toBe(false);
+      expect(result.reason).toContain('Command substitution');
+    });
+
     it('should block command substitution using backticks', () => {
       const result = isCommandAllowed('echo `rm -rf /`', config);
       expect(result.allowed).toBe(false);

packages/core/src/utils/shell-utils.ts

@@ -266,6 +266,11 @@ export function detectCommandSubstitution(command: string): boolean {
         return true;
       }
 
+      // >(...) process substitution - works unquoted only (not in double quotes)
+      if (char === '>' && nextChar === '(' && !inDoubleQuotes && !inBackticks) {
+        return true;
+      }
+
       // Backtick command substitution - check for opening backtick
       // (We track the state above, so this catches the start of backtick substitution)
       if (char === '`' && !inBackticks) {
@@ -319,7 +324,7 @@ export function checkCommandPermissions(
       allAllowed: false,
       disallowedCommands: [command],
       blockReason:
-        'Command substitution using $(), <(), or >() is not allowed for security reasons',
+        'Command substitution using $(), `` ` ``, <(), or >() is not allowed for security reasons',
       isHardDenial: true,
     };
   }