Peek inside executable, archive, image and other file structures

Analyzing file structures can be a complicated business, and definitely isn’t for the technically faint of heart. It can be useful for troubleshooting or security analysis purposes, though, or even when trying to identify a mystery file you’ve found somewhere on your PC. And whatever it is you’re trying to do, FileScanner is an interesting Java-based tool which just might be able to help.

The analysis process starts simply enough. Click File > Open File, or just drag and drop the target file onto FileScanner and it’ll automatically check the contents, before giving you a detailed report.

Is an image not displaying, for instance? Drag and drop a PNG, JPG or BMP file onto FileScanner and it’ll display the signature, headers, data blocks and other relevant information. If you understand the structure of that particular format then you may be able to spot what’s wrong. But even if you’re technically clueless about such things, you can still click the Image Data section to try and view the file contents, and perhaps click Edit > Export to save what’s left of the image in a new file.

Or maybe you can’t open an archive? Point FileScanner at a zip file and it’ll show you the various headers and data streams that the file contains.

Again, if you’re knowledgeable about such things then you can look for possible corruption, or try to find out more about the file (whether it’s encrypted, how it’s compressed and so on). But even if you’re an archive format newbie you may still be able to recover at least some files from the archive: just select them from the data stream, click Edit > Export and save them somewhere safe.

And it’s much the same story with executable files. Open a program and there’s plenty of PE Header-related technicalities to explore. But if you don’t care about those, then you can still use FileScanner to find images within the executable – icons, say – and extract them to disc. Simply expand the Resources section (Portable Executable Image > Section Data [.rsrc]), locate the images you need and click Edit > Export to save them.

What’s really useful about FileScanner, though, is it’s not just using file extensions and headers. As its name suggests, the program is actually scanning through a file, looking for and reporting on structures it recognises. So while FileScanner doesn’t directly support PDFs, when we opened one it still managed to detect and display the JPEGs it contained (which of course we could extract). And FileScanner doesn’t support Word DOCX files, either, but as they’re essentially ZIP files the program is still able to give you useful information about their contents, maybe even if they’re corrupted and can’t be opened elsewhere.

FileScanner does have a few issues. Information isn’t always displayed as clearly as we’d like; the interface could use a little work; and we’d like it to support more formats (being able to browse PDF contents in particular would be a great addition). It’s only a beta, though – we’re sure it’ll improve over time. And if you’re interested in this kind of low-level file analysis then FileScanner already provides more than enough features to justify the download.

Photo Credit: olly/Shutterstock

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