Gfrktyl

My laptop was confiscated by the military institute of my country and they made me to give them all my passwords (I cannot tell you the name of my country). They did not give it back to me for one week (yes, it was out of my sight for a while).
I nuked it from orbit but I just realised that it was on sleep state for 2 days and not in shutdown state, so it was connected to my modem via wifi. Does it need to be worried about?

and

I need to make sure if they have added something to monitor my activities or steal my data or not? And if they have done that, what should I do to prevent them.

Update

I have double checked the laptop physically and there is no sign of screw or plastic deformation. Is that still possible that they have compromised its hardware?

If the device left your sight for any amount of time, replace it. It can no longer be trusted.

The cost to assure it can still be trusted significantly exceeds the cost of getting a new one

There is effectively no way to verify that the hardware has not been tampered with without significant expertise and employing non-trivial resources. The only solution is to replace the laptop and all associated components. Without knowing your country or other aspects of the situation you are in, there is no way for me to comment on the likelihood of this, only on the technical feasibility.

If you do need to verify the integrity of the laptop, there are a few things to check (non-exhaustive):

• Weight distribution - Verify the precise weight of each component (IC, PCB, etc). Weight distributions can be analyzed using gyroscopic effects. This requires having uncompromised equipment nearby for comparison. Extremely precise measuring equipment is required.




• Power consumption - Verify the power consumption of each component over time. Backdoors often use power, and their presence can sometimes be detected with a power analysis attack. Do not rely on this however, as integrated circuits can use extremely little power nowadays.




• PCB X-ray inspection - Use X-rays to view the circuit board internals. This requires expensive equipment for a multi-layer printed circuit board such as a laptop motherboard. It also requires many man hours of intensive inspection of each square micrometer of the device.

Sounds excessive? It is, but this is what you would have to do to have a good level of confidence that no malicious hardware modifications have been made. It will be cheaper just to buy a new laptop.

I nuked it from orbit but I just realised that it was on sleep state for 2 days and not in shutdown state, so it was connected to my modem via wifi. Does it need to be worried about?

In theory, compromised hardware or firmware would be made to compromise your wireless access point or other devices listening in. While a suspended state (sleep mode) normally also disables the NIC, you cannot make that assumption if the hardware is compromised. However, while this is theoretically possible, it would require a far more targeted attack, and most military groups will not want to give away the 0days they have by shooting them at any nearby wireless device they can find.

Unfortunately, it is also theoretically possible that your modem has been compromised. I do not think that is very likely at all though, as they could have just done that through your internet connection, assuming they can control or compromise your ISP. If they have tampered with your hardware, it's much more likely that they have only done so for surveillance purposes, not to spread some worm.

I have double checked the laptop physically and there is no sign of screw or plastic deformation. Is that still possible that they have compromised its hardware?

Absolutely. There are many ways to open a laptop without that fact being apparent. While sophisticated chassis intrusion detection mechanisms exist, there are some "ghetto" techniques which you may be able to use in the future. One technique is to sprinkle nail polish with glitter on the joints of the system, inside and out. Take a high-resolution photo of this. If the device is opened, the precise layout of the glitter will be disrupted, and it will become exceptionally difficult to put it back in place. You can compare it with the stored photo and look for subtle differences.

The term for this is tamper-evidence, which is any technique that makes it hard to tamper with a device without that fact being noticeable. More professional options would include bespoke tamper-evident security tape or holographic stickers. Unfortunately, this can only help you in the future and will obviously be incapable of protecting your system retroactively.

Methodology aside, just assume that the laptop and anything within audio and visual reach of the laptop is compromised and therefore subject to monitoring as well as the activity on the computer itself.

Searching for, tampering with, or removal of the computer/monitoring devices might well be detected and seen as a criminal act. Also, complete destruction of the laptop or pointedly not being used can also be viewed with extreme suspicion.

All you can really do is continue to use the laptop, but with the knowledge that activity is being monitored (so only do "legal" stuff on it). Visual/audio monitoring devices need not involve the laptop being powered up.

Invest in a nice, secure, padded (and soundproof) laptop bag to store the laptop in when not in use.

The main information we are lacking is your threat model.

Is it likely that the military targets you specifically, and would be willing expand some resources on you? We don't need to know the details, but the answer changes depending on whether or not what happened is more or less standard procedure for your country, or you are being singled out.

And we don't know what secrets you are protecting. If you have personal data and communications, that's a different game than being an active element in a political opposition movement or other activity that might get you murdered if they get the data. There are countries in the world where being a human rights activist can get you on a death list.

If this is standard procedure, and your data isn't life-or-death, you can take the usual precautions, complete OS reinstall, firmware flashing, if you want to go the extra mile, replace components such as the Ethernet port and whatever else is replaceable. Then operate under the assumption that you might have missed something more deeply embedded, but your chances are better than average that you are clear.

The same is true for the active network connection. It is likely that your adversary did standard attack patterns. If your network is secured, and you don't see any signs of intrusion on the inside (firewall logs, IDS if you have, etc.) you could be fine.

If it is more likely that you received special attention, I would strongly suggest using the machine in some innocent ways (surfing the web, etc.) somewhere and then leaving it out in the open when you go to the toilet. Or in other words: Make it get stolen. That way nobody can blame you, the adversary cannot tell for sure if you intentionally "lost" the device and in any case can't prove it, and it's the only way to be sure. Even if you had it sitting nearby powered off, there could still be a microphone hidden inside that monitors you. So getting rid of it is the only safe option.

For the details, I can't do better than forest in his answer to show how deeply stuff could be hidden inside. They could've even switched out components with seemingly identical ones, plus backdoors. There are things you can do to hardware that the manufacturer would have trouble finding.

The same is unfortunately true for your network. There is always one more 0-day out there, and backdoors in network devices aren't exactly unheard of as well. If you are a high-profile target, you need to assume that the network has been compromised.

However, all of this advanced stuff isn't free or cheap. That is why the threat model is important. It is unlikely the military would use its best stuff on a random search.

In addition to what others have mentioned about detecting hardware changes (chiefly that it is nearly impossible), you should recognize that the most likely vector of compromise would be the installation of software, especially if they only had your device for a fairly limited period of time.

To have a reasonable level of certainty that your device is clean from software exploits you should throw out the hard drive and start with a fresh one and a fresh install. Many of the more practical (and easy) low-level rootkits modify the firmware on hard drives to prevent a normal format from removing the malware. This is also one of the easiest ways to alter a system fairly quickly and "undetectably". If your laptop has a replaceable network card, this would also be something to consider replacing as it is also another fairly useful place to deploy a hardware implant.

Lastly, any malware likely needs to phone home eventually. Start up your computer and any common applications you run. Connect it to an external router (this is important as you cannot trust software running on the laptop) that records all traffic. Let the laptop sit unused for at least 24 hours. Now, painstakingly validate all the IP's via ARIN or other registries, to see if any of them look suspicious. You will almost certainly have several that you cannot validate, even if the machine is not compromised, but this may give you some confidence-level of compromise. Do be aware that nation-states often possess the ability to inject traffic into legitimate streams from legitimate locations, and also may compromise legitimate services or use existing legitimate services (such as a service like docs.google.com where any user can create documents of arbitrary data). In addition network traffic on any network protocol is suspect and should not be discounted while trying to validate the traffic.

Lastly, think of your risk profile. Is your nation known for hacking devices and monitoring them? Are you a victim of bad luck or are there legitimate reasons why they should or did suspect you? A certain level of paranoia is healthy, but be practical with your assessment. Custom hardware implants are not cheap, and the cost of discovery can be both embarrassing and costly. If you are not a likely suspect and of some importance, the most likely implant will be software/firmware based, if anything was implanted at all. As others have pointed out, any credentials you had on your machine/that your provided/or any active browser cookies, and all files on the system should now be considered compromised.

If they have all your passwords, as you say, and had possession of the laptop, the laptop, its operating system and software installed are all suspect. As suggested, nuke from orbit.

I would also be concerned that any software that might possibly have been implanted could (and would) attempt to compromise other computers on connected networks. Do not connect this machine to an ethernet, nor power it on near any WiFi networks if it has WiFi (nor around Bluetooth devices though I know little about this).

It may not be possible to wipe it even under safe conditions due to compromised firmware.

If they had the laptop for, say, 30 minutes (or less), the drive could (and would) have been imaged/copied. Its secrets are no longer yours alone.

You also have some work ahead of you to change all your passwords: you might want to nuke the accounts for extra safety. Delete all content (if possible) and close the account. Good luck with that. Information may have already been collected, however.

There have been answers regarding hardware modification, and while this is a possibility, clearly software tampering should be high on your mind.