There has been a lot of news lately, and in the last few years, about Huawei being a security risk. Can someone explain what the basis is for the risk, other than speculation? Is there not a way to examine Huawei devices to see if there is indeed a chip, bootloader, backdoor, etc that could be exploited? What potential dangers exist in Huawei devices made in China, but not in other devices made in China, like those from Apple?
This article from the MIT Technology Review says that the U.K. has been vetting Huawei gear before deployment. It provides for only a limited level of assurance. The risks are loss of privacy, espionage, and sabotage.
I left the electronics/computer industry years ago but I think the following views are still applicable to the state of the art.
If espionage is intended, the manufacturer can make a device's code hard to access and inspect. A flash memory device might be part of a system-on-chip or system-in-package that obviates the need to present memory lines on the surfaces of the package. This would make code very inconvenient to access. In the extreme you may resort to using a scanning electron microscope (SEM). Courbon et al used a SEM to read a 210 nm flash memory. (The article is not dated but the most recent reference is from 2015 so the paper is at least as recent.) If you can access the code, you may then find that it was obfuscated. Obfuscated code is created when the programmer uses a program to turn the original code into a Rube Goldberg machine. Whether this is effective in hiding backdoors is debatable.
A custom chip can be a mystery. A chip "normal" in every way except identification looks like a mystery. A manufacturer can simply print phony or confusing identification on one or more of the devices on a board. A device can be made to look standard when it is in fact not. If any well funded entity were to invest in hiding or disguising functionality, it would take a huge amount of research to determine the "true circuit" of any single design . Until you know the true circuit, any inspection of the code provides no real assurance.
If you believe you need to go to much trouble to determine the true circuit and inspect code for a backdoor you may be better off just designing and building your own telecommunications equipment. More realistically you would install intrusive oversight in design, manufacturing, support, and updates and perhaps take over corporate governance through the nationalization of a maker.
If you are not going to be intrusive you are implicitly accepting a certain amount of risk and you are perhaps relying on commercial pressures to keep the manufacturer honest. That reliance might lead to disappointment.
If updates are disabled, you might conclude that a particular design is not a security risk after a certain amount of effort. You would not know if the effort made is insufficient and that a larger effort is needed. It may not be practical or even safe to disable updates. As soon as the code is updated you do not have any assurance. You may not be aware of the event of an update if the manufacturer tries to be stealthy.
There is a lot of speculation based on intelligence that has not been explained. That's not nothing, but it also isn't something.
Can the phones be inspected? Yes, but only based on function. The problem is not a backdoor or a bootloader, and there would be no need to add a suspicious chip because malicious functionality can be baked in. Any regular calls home would also be detected.
The problem is with "sleeper" functions. Imagine the phone has a "dump all data to home" function that was not enabled until an update was applied by the manufacturer. The update itself need not be malicious, just configured in such a way to turn the sleeper function on. Then the phone contents are uploaded. It might be detected, but by that time, the damage is done.
Security depends a lot on trust, and if a vendor cannot be trusted, then it almost doesn't matter if it is possible to inspect the product; there are too many ways that the vendor can break whatever trust was granted.
Your best bet is to monitor the network activity while the Huawei device is connected through your router/modem. If data is passing from your device to the internet for unknown reasons, particularly to IP addresses that you and your apps haven't requested, then there's good reason to suggest backdoor spyware.
The only way to truly know whether an operating system is spying on you is from monitoring your own network, unless you have access to the full source code of the operating system and are able to understand whether there is backdoor spyware code within the source. However, even with full source code of open source operating systems, it's very possible that there are backdoor spyware within the code that has gone undetected by thousands of developers who have read the code. This is simply because it's possible to make a backdoor function so undetectable that no one would even realize that it's there.
However, if you're not detecting data leaving your phone to unknown sources then it's unlikely that a backdoor is in place. It can still be hard to detect small bytes of data leaving your phone, which is enough to steal your notes, documents, emails, browsing history, passwords and other small files.
If the Huawei operating system has code in place to transfer your passwords over to its servers, it would require that you send 8 bytes of data over the network for a password that is 8 characters long. With so many apps, website addresses and other software constantly passing data to and from your device, detecting suspicious transfers for data that small becomes incredibly difficult. Even the most savvy of IT specialists might have difficulty proving whether the device is spying on them or not.
Also worth noting is the concern that even if it were somehow proven that Huawei isn't spying on users, they could always update their operating system remotely and then with each update, it would have to be reproven that they are not spying. Because every OS update could have included code that transfers your data to their servers.
It has become so easy for software to spy on you that people should become aware of the issue that any and all of your computer's data can be accessed at any time by software and operating systems that you have installed by bad actors who choose to spy on you.
What the world really needs to have are operating systems that make it easier to monitor all of your network activity while giving users the ability to block any network requests from sources that have not been approved. In other words, people need devices where their data cannot be sent over the network except for exactly the data that they want to send. The reason the world needs this is because currently, there's no reason to believe that major US tech companies and government aren't spying on users already. Even some small app developers are doing it. It's just too easy, and too tempting for many not to do it. And the problem of spying will likely get worse as developers begin to understand the programming mechanisms to implement such spying. Unless ample measures are taken to prevent spying on these devices, people in the future should safely assume that everything they are doing is being collected and stored, usually for AI algorithms to process. If people want the internet to have any amount of privacy, large steps have to be taken to ensure it. And there's almost no way to know whether or not Huawei provides privacy or if it's spying on its users.
The U.S. government is terrified of Huawei controlling and implementing 5g networks because it understands that telecommunication providers have access to everything that users do on the network. The telecommunication companies in America literally can see everything that everyone is doing. Luckily, despite these telecommunication companies having an almost all-knowing power, it doesn't seem that the power has been terribly abused as of yet. The U.S. government is rightly afraid of any other country having such a power over our own citizens.