# If a hacker is on the same Wifi Network as I am, what can he do? [duplicate]

Ok so when a hacker has the wifi network's password and gets on the network, he can do things like monitor traffic, catch passwords, even access PCs, etc.

But what I'm interested of knowing is what can he do to my computer once he gets access. I have 4 questions for this:

1. If he's doing something to my laptop, will I notice?

2. Hackers can copy data stored on my laptop, but can they possibly retrieve permanently deleted files? (empty recycle bin type of delete or shift + delete)

3. My OS, Firewall, and Antivirus is up to date so what are the chances of me getting hacked?

4. Is it possible for an attacker to leave no trace? Like, he installs a program and the program was set to uninstall itself to leave no trace? Is that possible?

THANKS! Also just a reminder I'm talking about attacks happening on the same wifi network, not over the internet. Thanks again.

## marked as duplicate by TildalWave, Adi, NULLZ, Mark Davidson, GillesMay 24 '13 at 12:53

If he's doing something to my laptop, will I notice?

Probably not if the hacker is in any way competent.

Hackers can copy data stored on my laptop, but can they possibly retrieve permanently deleted files? (empty recycle bin type of delete or shift + delete)

There is always a possibility. "Permanently deleted" files aren't really deleted. Traces of it most likely still exist on your hard disk.

My OS, Firewall, and Antivirus is up to date so what are the chances of me getting hacked?

There is still a good chance. There any zero-day vulnerabilities in almost any software under the sun. There is a good chance a hacker can get into a fully patched system. Of course, this is no excuse to skimp on the patching.

Is it possible for an attacker to leave no trace? Like, he installs a program and the program was set to uninstall itself to leave no trace? Is that possible?

Yes of course, what you are talking about is a rootkit.

1) Depends on how your computer is setup and how observant you are. It shouldn't be obvious if they are competent, but little things like unexpected CPU and Hard drive usage are not really something that they can easily prevent from being visible. There are normal activities that can cause random CPU and HDD activity, but an attempt at hacking would have to use CPU and HDD resources.

2) If the file is recoverable using un-delete utilities then there is no reason an attacker couldn't also get to it if they are able to get in to your system sufficiently. They aren't magic, if an attacker can compromise your system enough remotely, they can accomplish anything they could accomplish while sitting at your computer that doesn't involve having to actually alter the hardware. To securely delete a file, information has to be written over top of the locations where it was stored on disk.

3) As long as you are patched up, there isn't much chance of them getting on as long as you don't have things open to the local area network. If you have file shares and such available to the LAN, then the chances go up significantly, but if your computer is reasonably locked down, then the chances drop to pretty much zero unless you are talking about a very sophisticated attacker targeting you directly.

4) Absolutely, but it would be very difficult. To leave no trace at all, they would have to backup the bytes used on any section of the hard drive that they write to and then restore it before they leave or would have to run entirely in memory. Forensic tools are designed specifically to avoid altering a system in any way. These could be adapted for use in a hacked computer to similarly avoid leaving a trace of their use. That said, unless you are specifically targeted, they are most likely going to leave a trace to keep a back door open for them in the future, but it isn't a guarantee.

1) Probably not considering the questions you ask :)
2) Depends what you mean by "permanently deleted", but I believe the answer is "yes" - see 1.
3) Low
4) Yes

I believe somebody can spend and hour writing up an answer to your questions as they are very broad and you give no specific information.

1) As answered, depends on the skill level of the attacker. However, you should treat an attacker as an attacker period. Whether they are attacking via a wireless network, or sending you a client side attack.

On the client side attack, the compromised machine thereby becomes the attacker.

2) Because they are on your machine, nothing is stopping them from installing tools to recover deleted files. You can overcome this by using "shredding" tools.

3) Your OS, Firewall and Antivirus will do little against a client side attack and or malware since most tend to shut them down.

Antivirus is only good for KNOWN threats. If I create something capable of exploiting you RIGHT NOW, no AV in the world knows about it and will not flag it as a threat. I could get into "packers", "obfuscation", etc., but its overkill. Antivirus is not a sure-fire solution.

4) Absolutely. Some of the best attackers are the ones who are unseen. This however, takes a lot of planning, and strategy. In order to even erase their steps, they need to perform certain tasks, which means when gone, there will be residual data however, scripting and scheduling can overcome this.

Now to quote:

As long as you are patched up, there isn't much chance of them getting on as long as you don't have things open to the local area network.

This is only applicable to a network based threat, where an attacker is specifically AIMING at a target. However, if on the same network, nothing will stop me from say modifying a page he is seeing which can allow me to inject something into the stream (think netsed here).

if your computer is reasonably locked down, then the chances drop to pretty much zero unless you are talking about a very sophisticated attacker targeting you directly.

This is far from the truth. Most malware authors bypass a lot of defenses using iframes and other forms of attacks on the "MOST LOCKED DOWN SYSTEMS." This is because the attack vectors are not truly understood. Now remember, this thread is about a WiFi network but the point not being thought of, is the network based attack. If I am on your network, perhaps there is the possibility I can MITM your connection:

You --> wifi router --> Internet --> Google


In this example

me --> ARP POISON --> Router & Clients
me --> re-route everything going out --> from clients --> to me --> to router

You --> open Google --> (what you think is your router) --> me
me --> (here is this quick iframe script using SET (Social Engineering Toolkit)) Here is your Google page--> you
Your machine --> open up a connection to me (game over)