diff --git a/src/com/android/messaging/ui/conversationlist/ShareIntentActivity.java b/src/com/android/messaging/ui/conversationlist/ShareIntentActivity.java
index ef7fcef..396f1da 100644
--- a/src/com/android/messaging/ui/conversationlist/ShareIntentActivity.java
+++ b/src/com/android/messaging/ui/conversationlist/ShareIntentActivity.java
@@ -34,6 +34,7 @@ import com.android.messaging.util.Assert;
 import com.android.messaging.util.ContentType;
 import com.android.messaging.util.LogUtil;
 import com.android.messaging.util.MediaMetadataRetrieverWrapper;
+import com.android.messaging.util.FileUtil;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -158,8 +159,12 @@ public class ShareIntentActivity extends BaseBugleActivity implements
     }
 
     private void addSharedImagePartToDraft(final String contentType, final Uri imageUri) {
-        mDraftMessage.addPart(PendingAttachmentData.createPendingAttachmentData(contentType,
-                imageUri));
+        if (FileUtil.isInPrivateDir(getBaseContext(), imageUri)) {
+            Assert.fail("Cannot send private file " + imageUri.toString());
+        } else {
+            mDraftMessage.addPart(PendingAttachmentData.createPendingAttachmentData(contentType,
+                    imageUri));
+        }
     }
 
     @Override
diff --git a/src/com/android/messaging/util/FileUtil.java b/src/com/android/messaging/util/FileUtil.java
index 7c47ae9..f8051ed 100644
--- a/src/com/android/messaging/util/FileUtil.java
+++ b/src/com/android/messaging/util/FileUtil.java
@@ -16,7 +16,10 @@
 
 package com.android.messaging.util;
 
+import android.content.ContentResolver;
 import android.content.Context;
+import android.net.Uri;
+import android.text.TextUtils;
 import android.webkit.MimeTypeMap;
 
 import com.android.messaging.Factory;
@@ -116,6 +119,20 @@ public class FileUtil {
         }
     }
 
+    private static boolean isFileUri(final Uri uri) {
+        return TextUtils.equals(uri.getScheme(), ContentResolver.SCHEME_FILE);
+    }
+
+    // Checks if the file is in /data/data/com.android.messaging
+    // The other app folders are either symlinks to this, or hold non-private data like binaries.
+    public static boolean isInPrivateDir(Context context, Uri uri) {
+        if (!isFileUri(uri)) {
+            return false;
+        }
+        final File file = new File(uri.getPath());
+        return FileUtil.isSameOrSubDirectory(new File(context.getApplicationInfo().dataDir), file);
+    }
+
     /**
      * Checks, whether the child directory is the same as, or a sub-directory of the base
      * directory.