This data is often not present in photos even when unmodified, but when it is present it is very helpful. IPTC data contains other data such as copyright information, the photographer’s details, and a caption etc. This marker denotes the start of metadata generated by Photoshop processing. Apple products) it is still sometimes possible to determine the manufacturer of a device from this information.įF ED – Photoshop and IPTC data. This can be important for OSINT because even when most websites remove EXIF data, the ICC profile is often left intact (assuming it was present at the outset). An ICC profile is a set of properties that determine how a particular device displays colours. There’s a full list of all the useful JPEG codes here, but there are only a few that we’re interested in:įF E1 – the start of any EXIF data within the file.įF E2 – ICC (International Colour Consortium) profile information. These are all located in the file header, which is the first part of the file before the main bulk of data relating to the actual image itself. So what has this got to do with EXIF and other file data that we might interested in? Just as there are specific hexadecimal characters that indicate the start and end of a JPEG file, there are other hexadecimal patterns within the file that indicate where specific kinds of information are to be found. Notice it starts with the file signature FF D8, which indicates it is a JPEG:Īnd the file ends with FF D9, which indicates the end of the JPEG: By opening it with a hex viewer we can seen the file (almost) as the computer would. Here’s how the computer sees the same image. Here’s how your computer presents the image to you: For a quick example, let’s look at a picture from today’s news. The end of the file is marked by a corresponding “ FF D9“. This means that when a computer is reading data, it sees “ FF D8” at the start of a file and knows that it’s a JPEG. Don’t worry if all this is completely alien, it’ll all be clearer shortly! There’s a full list of common signatures here. docx file starts with 50 4B 03 04, and a a JPEG image file starts with FF D8, and so on. exe file starts with the signature 4D 5A, a. Every file starts with a hexadecimal file signature that tells the operating system what kind of a file it is. xls) to decide what program to use to run the file, although this is actually less important than you’d think as far as the computer is concerned. In Windows the operating system looks at the extension on the end of a file (e.g.pdf. What’s Inside A JPEG?Įvery type of file has its own digital signature – it’s how a computer can tell a. Using a hex reader is the most comprehensive way to inspect the structure of a file and it will allow us to inspect the metadata very precisely. HxD is also a good basic hex viewer for Windows, but any hex editor will do for this purpose. It’s not quite down to the ones and zeroes, but almost. It isn’t as immediately easy to use as Forensically, but it is more effective for viewing recovered metadata.īless – Bless is a hex editor that allows you to see the structure of a file in its rawest possible form. There’s a simple setup guide here and this is a useful video tutorial for Windows. The tabs “Meta Data”, “Geo Tags” and “String Extraction” will be useful for accessing the data we need.Įxiftool – this is a simple but very powerful tool for extracting metadata from many different file types, not just images. Simply load an image with “Open File” to begin analysing it. There are three that I’m going to refer to in this article.įorensically – this is a very simple web-based image forensics tool that runs in your browser. There a few tools that are useful for extracting data from JPEG image files. In this post we’ll dig into the world of digital forensics and see that there are still little details hidden away inside web images that can prove to be useful. This means that working with primary sources is always better than secondhand images that have been processed – but it doesn’t mean that we should abandon image metadata altogether. EXIF data features in every OSINT course or CTF that I’m aware of but as a rule most platforms remove EXIF data from images and finding it in the wild is quite rare. EXIF is an information goldmine because it contains information about the camera, settings, and sometimes even location data, but you’ll be very lucky if you come across EXIF data in an image on the web or any kind of social media platform. The most well-known of these data types is EXIF data. Beyond the visual appearance of an image there is often additional information hidden within an image file that can be just as useful. Much less well known is the usefulness of image meta- and file data for research purposes. Using photographs for OSINT purposes is not new but almost all work of this kind mostly focuses on the visual content of images.
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