Unverified transaction fron Electrum wallet

[Lucius]

How about Guard Provider app or any anti-virus pre-installed on your phone?

Read this article below.
- Xiaomi phones came with security flaw preinstalled

From article :

Guard Provider gets its updates through an unsecured HTTP connection, he said. This means that if an attacker was on the same Wi-Fi network as a potential victim, the hacker could insert malware in those updates through a "man-in-the-middle attack." That's when a rogue network is set up to look exactly like the one you're connected to and tricks the victim's device into connecting to the fake Wi-Fi. Using the vulnerability, a hacker could've interrupted Guard Provider's update process and added malware that would steal data, install tracking apps or plant ransomware, Makkaveev said. The attacker would have to time this to when the updates are happening and also know the file name of the update -- which is not difficult to figure out because they follow a template, said Yaniv Balmas, Check Point's head of research.

If we add to all this that Xiaomi is fix this security-flaw last year, and that OP is lives in the farm in the village, which means there probably aren't many neighbors who are capable of making man-in-the-middle attack, then such an option is not exactly the most probable reason for the loss of funds. However, this attack vector should not be neglected either, it is possible that the OP has used some public wireless network or has neighbors who are skilled in hacking.

[talliar]

I used only LTE from my mobile operator (TELE-2). We doesn't have any wifi networks in our place, so far away from the city (60km).

These days I was trying to understand how this happened. But all the known cases come down to is downloading the Electrum application from fake sites or entering a seed phrase in third-party applications. I didn’t do either one. the question is still open for me. It would be great if there were logs in the electrum, in which you could see from which application the transaction was made or any data about the device. but as I understand it is impossible.

[HCP]

It would be great if there were logs in the electrum, in which you could see from which application the transaction was made or any data about the device. but as I understand it is impossible.

I think you misunderstand how Bitcoin works. The transaction was in all likelihood, not sent from your device.

Once someone has your seed or private key(s), they can simply clone it into a wallet on their own device (pc/mobile) and then have full access to your funds. The most likely explanation is that someone has access to your seed.

However, the difficult part for anyone to figure out is how that person got access to your seed... usually, the answer is, like you say, because of fake apps or people storing seeds digitally (screenshots, emails etc)... but according to you, none of that is true in this case.

In that case, you would need to sit down and think of everything that has happened since you installed the wallet and started using it to try and find the hole in your security. There isn't really a lot else that other people can do for you at this stage