The previous article about information security focuses on how to be invisible on the Internet. In addition to the technical instruction, we also told about the errors of the «human factor». However, «torified» traffic, while preventing any IP-address leaks, does not save from other paths to lose data or giving yourself away. About one of the least obvious – read in this article.
Some significant points from the previous article
When a computer connects to Tor, a user’s actions on the Internet are (almost) impersonal. It becomes impossible to track the person’s location, IP-address and other data. However, there are a number of ways to find out where you are and what you are doing: the use of bank cards or phone compromise any information about purchases, movements, calls. Suppose you do not make errors of «human factor» and have successfully installed Whonix according to our instructions. The next step for secure communication or activity on the Internet will be to clean up metadata.
For what reason it is used and why metadata is dangerous
Metadata is an information about a file on your device inside the object itself. To make it easier to understand, let’s take a picture on your phone for an example. The picture has both data (information about where and what color the pixel is) and metadata (it helps to identify a device with which the photo was taken, geolocation at the time of shooting, the size of the image). Metadata improve the quality of information, as it can help to structure the data and set its context. It is used in different areas for analytics, increases the speed of systems and optimizes communication between computer software and files, establishes software licensing restrictions.
Despite all the advantages, metadata is dangerous when you seek to anonymize your activities. The fact is that they provide much more personal information about the user than the IP-address. For example, you can find out where a person spends most time (home and place of work), geolocation, devices’ operating system, date of video shooting or creation of a text document, authorship. In Digital Security research «II Files’ metadata: Invisible information, revealing your identity», experts note that mail services, even Protonmail, which is considered the most secure, do not delete metadata at all. Messengers erase all metadata from photos, but files (including images sent as files), video and text documents remain intact. Therefore, anonymizing traffic with Tor makes no sense if you do not delete metadata from published or sent materials, as you become easy to track.
Security tools
You probably don’t need such a serious anonymization yourself in regular life, so this utility is related to Whonix (Linux’s distributive from the previous part). However, I cannot advise nothing to clean metadata ordinary users too. For laypersons online resources will be suitable, for example, imgonline. But this method has two obvious drawbacks. Firstly, information will be transferred to a specific site, and secondly, the number of file formats which metadata can be deleted is much smaller.
For Linux there is a special software to clean metadata: «MAT – Metadata Anonymisation Toolkit». There are two versions: MAT and MAT2. The last one is more convenient and easier to use. To download the software, you need to enter the command in the Whonix terminal:
$ sudo aptitude install mat2
To view all available commands, type:
$ mat2
Then the list of actions will appear:
To use any command, you must first write the tool name – mat2. The most interesting of the proposed commands is called «–inplace» which removes all metadata. Unfortunately, to address a specific object, you need to specify its directory, so to make this action easier, you should place the files in the system, for example, on the desktop. Write a request in the terminal line:
$ mat2 –inplace /home/user/Desktop/имя файла
We tested the operation of this method by cleaning the metadata from the picture from the gallery, comparing the size of the file before and after: 3.3 MB and 2.3 MB respectively. Almost a third of the information is «data».
Of course, photo does not take up much space on the hard drive, and if you take a larger file, the share of metadata will be insignificant. However, the most popular files distributed by people are images, video, audio and text documents. Together with them, a significant amount of information, however hidden from the average user, but confidential, is transmitted.
