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To access shared files on my Windonw 7 computer, another person can go through the wireless network and provide the correct user name and password and access those files.

I heard a 802.11b or g wireless password (correction: WEP encrpytion key) is very easy to break. If someone cracks the wireless password and then tries to loop through all password combinations using brute force, will Windows 7 actually give a warning on screen saying someone is trying to break into your system or someone tried more than 30 times with the wrong password trying to get access? I never read a Windows 7 book saying that there are such warnings.

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What password are you trying to stop them from guessing? The Windows password or the network password? Your question conflates the two. –  Steve Rowe Dec 7 '09 at 0:43
    
the question says, "if the kid cracked the wireless password and then tries to get access to the shared folder content by looping through a password list" –  動靜能量 Dec 7 '09 at 8:55
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@Phoshi: I'd argue that living next to NASA would have nothing to do with ability to crack passwords. Now, if you had said the NSA.... –  Chris Lively Dec 7 '09 at 14:57
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I figured NASA would be more likely to have a lot of computing power currently untapped. The NSA are already in your networks :P –  Phoshi Dec 7 '09 at 21:03
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Use something better than WEP? In security you need to think proactive, not reactive. Merely waiting for a flag to appear in your logs is a reactive measure. Personally I would be more worried having someone on my wireless network, because there are no flags or logs to warn me if someone has got access. You don't need to break into someones computer to do evil things on a network. –  Qwerty Dec 8 '09 at 0:24

4 Answers 4

up vote 11 down vote accepted

Windows doesn't display a screen warning but you can audit the logon attempts:

  • Log on as an administrator

  • Click Start, click Run, type mmc /a (note the space between mmc and /a), and then click OK.

  • On the File menu, click Add/Remove Snap-in, and then click Add.

  • Under Snap-in, click Group Policy, and then click Add.

  • In Select Group Policy Object, click Local Computer, click Finish, click Close, and then click OK.

At this point, you might want to save this console for further use. Note: you can add multiple snap-in and manage multiple computers from this console.

  • On the left hand side, navigate to Local Computer Policy > Computer Configuration > Windows Settings > Security Settings > Local Policies > Audit Policy

  • On the right hand side, double-click "Audit Logon Events"

  • Check the boxes for Success and Failure, click OK

Now anytime a logon is attempted an entry will be created in the Security Log, which you can view with the Event Viewer.

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Steps 2 through 5 can be shortened to: Click Start, Run..., Type gpedit.msc and click OK –  Travis Dec 7 '09 at 17:20
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Hackers rarely bother to brute force passwords, they spearphish instead, just like theives usually skip the front door and its expensive lock, and go to the back-door or a window which are usually left open. Use a good password. If you have long password with a mixture of character types, they will need Billons and billions of tries to guess it, auditing might be fun, but they will be comming at you from another direction. –  DanO Feb 5 '10 at 23:19

In addition to Molly's sage advice to audit login events, I would recommend instituting a lockout policy. In the same MMC snapin that you enable auditing, find the account lockout options. Set a maximum number of attempts (5 is standard) and a lockout duration (30 minutes is standard). Then if there are 5 failed login attempts within 30 minutes, it will lock out your account for 30 minutes. You won't be able to log in, but nor will they, and then you'll clearly know that somebody is tampering with your system. Note that The Administrator account cannot be locked out. All other accounts on the computer will be subjected to this policy though.

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No it doesn't.

Suggestions:

Create strong passwords and change them every three months--that usually helps. Another thing I incorporate, is start the password with a space. Additionally, I recommend using phrases, than words. Finally, you could try an encryption solution for additional security, giving access to specific users.

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Doesn't really answer the question... –  Nathaniel Dec 7 '09 at 20:45
    
Thanks. Perhaps I should have made it a comment, it was intended to be a suggestion, Nathaniel, considering the question was already answered like 3 times. –  AdminAlive Dec 7 '09 at 21:00
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It does answer the question, actually. He said "no". –  Phoshi Dec 7 '09 at 21:03
    
Yeah, you're right, Phoshi. Huh, I barely remember this question... lol. –  Nathaniel Jan 18 '10 at 5:29

802.11b and g have nothing to do with "passwords." WEP, which is a form of encryption for a wireless connection can be cracked very easily. WPA and WPA2 are Authentication methods that usually use AES as a form of encryption to keep the connection safe. If you use WPA2 with AES and a strong pre-share key you have nothing to worry about as far as your wireless security.


Some routers manufacturers, such as Buffalo, allow for multiple WLANs and can segregate the traffic from your wired network essentially creating a guest WLAN. If you want to have your WII, iPhones, etc on a weak WEP connection (Wii and DS only support WEP anyway which sucks) then you can say that that specific wireless network cannot interact with any wired devices. You can have one WLAN with little or no security for guest access that cannot interact with your wired network and one with good security for your own devices that has full network access. the DD-WRT and Tomato firmware also allow for this.

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It should be mentioned that a "strong pre-share key" should ideally have 256 bit. If you use a completely random (!) passphrase with upper & lower case letters and digits, you would need ca. 42 characters. You could probably get by with a bit less, but the rule of thumb is: If you can remember it, it almost certainly is not a strong password. –  sleske Dec 7 '09 at 0:59
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Of course, writing down the password on a note attached to your router is perfectly OK. If you can access the router, you can reset the PW anyway... –  sleske Dec 7 '09 at 0:59
    
One problem is authorizing friends who come over. We've got two laptops, two iPhones, and a Wii on our wireless, and friends show up now and then with smart phones and laptops. Ever tried typing something complicated on a Wii? The basic problem is that password cracking has advanced beyond normal human password abilities. –  David Thornley Dec 7 '09 at 15:11
    
yes, it is WEP vs WPA... i forgot that as I keep on thinking that 802.11i gives really good wireless security –  動靜能量 Dec 8 '09 at 0:02

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