Second hand xbox 360 infected with malware. need xbox 360 s operating system download link

I've finally debunked this annoying issue, after replacing the 500mb homeplugs with 1gb ones, I still had the issue, I reset to factory settings the router that the Xbox 360 & Xbox One are connected to , and still had the issue, I reset to factory settings
on the Xbox 360 and recovered my gamertag again, but still had the issue.

I then, as a last resort checked the Primary & Secondary DNS settings on the TPlink adsl modem, and noticed that the primary settings had been changed. I'd already had this happen with the Apple Airport Extreme router via malware despite having plenty of
anti-malware / security programs scanning our PC's, the malware uses exploits

I reset the modem, run the setup, changed the Primary & Secondary DNS IP's to Googles Primary 8.8.8.8 and Secondary 8.8.1.1 and it's been fine since and I check the modem's settings every couple of days..

I've included further info incase it helps anyone.

DNSChanger, a form of malware, redirects your Internet traffic to alternative websites, allowing the malicious operator to control the customer’s Internet experience. A common method is to redirect advertisement traffic to sites controlled by the malicious
operator. This malware can also allow infected computers to be controlled remotely. Details about this malware, how it can attack, and how your system may have been infected, can be found on the following FBI and Department of Justice website.

DNSChanger malware causes a computer to use rogue, or bad, Domain Name System (DNS) settings in one of two ways. First, if the malware successfully infects the customer’s computer(s), it changes the DNS settings to replace the good ISP settings with rogue
settings that are then operated by the malicious operator. Second, if the malware infects a router or gateway device on the customer’s network, all computers located behind the router or gateway device within your network could be controlled by the malicious
operator. Therefore, these changes may impact all computers on your network, even if those computers are not themselves infected with the malware.

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Bears, the very different operating system ('Dashboard') of the Xbox 360 can't host Windows trojan malware, that is definately not the cause of the issue.

If it connected to the internet it possible to be targeted. To gain access to network and sniff traffic etc. They have found malware infecting even fridges and smart TV'S. Why not Xbox 360.. A teen mad malware in india for the kinect

The current operating system on the console does not allow external changes from malware or rootkits. Misleading pop-ups may appear using Edge for web browsing, but the console cannot be infected.

You would need to do a system update and this would update any apps like this that are part of the operating system.

https://support.xbox.com/en-US/xbox-360/console/system-update-operating-system

https://support.xbox.com/en-US/xbox-360/console/system-updates-info

these links should help you do this and provide some information on the updates.