Fix unsafe PowerShell execution in notification standard library

Co-authored-by: Tcode-Motion <188012755+Tcode-Motion@users.noreply.github.com>

Author: google-labs-jules[bot]

stdlib/src/notification.rs

@@ -1,3 +1,37 @@
+pub(crate) fn build_powershell_notification_args(title: &str, body: &str) -> Vec<String> {
+    use base64::Engine;
+
+    let b64_title = base64::engine::general_purpose::STANDARD.encode(
+        title
+            .encode_utf16()
+            .flat_map(|c| c.to_le_bytes())
+            .collect::<Vec<u8>>(),
+    );
+    let b64_body = base64::engine::general_purpose::STANDARD.encode(
+        body.encode_utf16()
+            .flat_map(|c| c.to_le_bytes())
+            .collect::<Vec<u8>>(),
+    );
+
+    let script = format!(
+        "Add-Type -AssemblyName PresentationFramework; [System.Windows.MessageBox]::Show([System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String('{}')), [System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String('{}')))",
+        b64_body, b64_title
+    );
+    let b64_script = base64::engine::general_purpose::STANDARD.encode(
+        script
+            .encode_utf16()
+            .flat_map(|c| c.to_le_bytes())
+            .collect::<Vec<u8>>(),
+    );
+
+    vec![
+        "-NoProfile".to_string(),
+        "-NonInteractive".to_string(),
+        "-EncodedCommand".to_string(),
+        b64_script,
+    ]
+}
+
 use crate::{StdFunction, StdlibModule, StdlibRegistry};
 use std::collections::HashMap;
 use std::rc::Rc;
@@ -32,21 +66,10 @@ impl StdlibRegistry {
                     let body = args[1].to_string();
                     #[cfg(target_os = "windows")]
                     {
-                        use base64::Engine;
                         use std::process::Command;
 
-                        let b64_title = base64::engine::general_purpose::STANDARD.encode(title.encode_utf16().flat_map(|c| c.to_le_bytes()).collect::<Vec<u8>>());
-                        let b64_body = base64::engine::general_purpose::STANDARD.encode(body.encode_utf16().flat_map(|c| c.to_le_bytes()).collect::<Vec<u8>>());
-
-                        let script = format!(
-                            "Add-Type -AssemblyName PresentationFramework; [System.Windows.MessageBox]::Show([System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String('{}')), [System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String('{}')))",
-                            b64_body, b64_title
-                        );
-                        let b64_script = base64::engine::general_purpose::STANDARD.encode(script.encode_utf16().flat_map(|c| c.to_le_bytes()).collect::<Vec<u8>>());
-
-                        let _ = Command::new("powershell")
-                            .args(["-EncodedCommand", &b64_script])
-                            .spawn();
+                        let args = build_powershell_notification_args(&title, &body);
+                        let _ = Command::new("powershell").args(&args).spawn();
                     }
                     #[cfg(not(target_os = "windows"))]
                     {
@@ -127,4 +150,31 @@ mod tests {
         assert_eq!(alert.name(), "alert");
         assert_eq!(alert.arity(), 1);
     }
+
+    #[test]
+    fn test_powershell_notification_args_security() {
+        let title = "Test Title'; Remove-Item -Path C:\\ -Recurse -Force; '";
+        let body = "Test Body\n\"'$$\x00";
+
+        let args = build_powershell_notification_args(title, body);
+
+        assert_eq!(args[0], "-NoProfile");
+        assert_eq!(args[1], "-NonInteractive");
+        assert_eq!(args[2], "-EncodedCommand");
+
+        use base64::Engine;
+        let script_bytes = base64::engine::general_purpose::STANDARD
+            .decode(&args[3])
+            .unwrap();
+        let u16_chars: Vec<u16> = script_bytes
+            .chunks_exact(2)
+            .map(|chunk| u16::from_le_bytes([chunk[0], chunk[1]]))
+            .collect();
+        let script = String::from_utf16(&u16_chars).unwrap();
+
+        assert!(script.contains("Add-Type -AssemblyName PresentationFramework"));
+        assert!(script.contains("[System.Windows.MessageBox]::Show"));
+
+        assert!(!script.contains("Remove-Item"));
+    }
 }