Our Macs store a lot of information which we can’t see readily. Much of the time this is very useful. If you can’t remember where you downloaded a file from, it should be shown in the More Info section of the Finder’s Get Info dialog. When you discover that the latest version of a document you’ve been working on is missing a couple of paragraphs, you can Browse All Versions and find an earlier version in which they still appear.
Sometimes, though, all this metadata and extended information can trip us up. I’ve shown how this can undo attempts to redact a PDF document, for example, and anyone working with private or sensitive documents or data needs to be very careful that they don’t leak through these friendly features. Despite the advances in privacy brought in macOS Mojave and Catalina, macOS still doesn’t offer any simple feature to clean documents or a thumb drive of potentially damaging content like this.
Over a year ago, I developed a free utility Scrub, which is designed to strip out a lot of hidden data which could prove damaging if examined by third parties. These include:
- extended attributes (xattrs), which often contain download source and time and much more,
- Spotlight metadata, which opens the contents of documents to search,
- versions, which may contain material which was later removed or redacted from a document,
- the QuickLook cache, which in High Sierra and earlier could readily show previews of images and other files you have used,
- system logs, which can contain entries revealing your Mac’s activities in the previous 20 days or more,
- datestamps on files, which reveal when a document was created and last modified.
Removing those is a serious and committing action. By definition, you can’t have an Undo, and used inappropriately, Scrub can cause damage and lose data. To help you avoid that, it works in two phases: you first perform an audit of the volume/folder/document you want to scrub clean, and that lets you know of any particular dangers in doing so. When you’re happy that what you’re intending to do won’t cause damage, you can then run the scrub to clean those files.
This is ideal, for example, when you need to clean a ‘thumb’ drive containing sensitive documents. Used without great care on your Home folder, it will cause severe damage which you may find very difficult to reverse.
This first full release of Scrub:
- checks its code integrity when it’s first opened;
- is compatible with El Capitan to Catalina, although not all features are available on every supported version;
- has a detailed Help book, supplied as a separate PDF as well;
- has several cosmetic improvements, such as resizeable text and better saving of window sizes and positions.
It has been hardened and notarized for compatibility with Mojave and Catalina.
Please use it wisely.