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| Subject: | RE: Serious Security Issue in Windows XP SP2's Firewall |
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| Date: | Wed, 22 Sep 2004 20:14:23 -0400 |
Inline with snippage... (but in a nutshell, your instincts are correct, Tim)
In other words, this caused the service to be releasedworldwide throughthe dial-up connection as soon as you were connected to theInternet.
Um, what are these people smoking? They're saying that when you establish a point-to-point dial-up connection and have F&P Sharing enabled, you're somehow magically exposing your machine to the planet?? Am I misunderstanding their claim?
Microsoft at that time issued an update to patch the bug.The fact thatfile and printer sharing since then is not connected to the dial-up connection anymore, can easily be seen on your system:Right-click on thesymbol "My Network Places" and select "Properties". Repeatthe right-clickand selection with the icon of your dial-up connection andselect the tab"Settings". If there is no check at "File and Printer Sharing", it indicates that this service should not be made availablethrough yourdial-up connection.
I cannot confirm or deny that this is a default setting as I have FPS disabled on all of my connections and do not recall what the default settings were.
This in fact is true for Windows XP without Service Pack.Since SP1, thisconfiguration is hardly more than cosmetics and does notserve any purposeanymore. This means, the file and printer sharing service is connected in general, also to the dial-up network adapter.
Okay, call me thick or confused, but what does this mean? What are they talking about- A dial-up adapter, or a network adapter? Is this a translation thing? I have absolutely no idea what the above is supposed to say.
This initself is a seriousbug, since your shared data potentially could be seen onthe Internet.
Gee, now it's not "the world" and it's only "potentially"?
However, there are no catastrophic effects, as everydial-up connection isconfigured with an activated firewall by default. If you intended to deactivate this firewall, Windowsdisplayed an easilyrecognizable dialog, that this choice would allow access toyour computer.Despite the bug in SP1, the configuration of the firewallwas worked outin a clean way: You were able to run the dial-up connection with a firewall and the internal network card without, because thelatter wassupposed to enable access through the Windows network.
Okay, fine, whatever. I have some of my connections firewalled and others not. That didn't change with SP2.
SP1 + SP2 leads to a catastrophic error Due to the bug carried over from SP1 as well as a new bug,the firewallconfiguration with SP2 has a catastrophic effect. The SP2installationsimply uses the previous configuration of the firewall: Ifit was activefor the dial-up connection, now it also has been activatedfor the networkadapter.
Are they talking about the enabling of the firewall? If so, they're wrong. Are they talking about the enabling of FPS system-wide? If so, they're wrong. Are they saying that *if* a luser, er, user were to do something like go and enable FPS on a dial-up connection but not on a LAN connection, that installing SP2 would then enable FPS on the network connection, as well? If so, I have no idea if it's true as I'd not do something like that. However, I see nothing on my system to indicate that this is true.
At the same time, an exception is determined for file andprinter sharing:For the internal network card - and astonishingly also forall adapters.
Not on my machine. At all.
With the first use of the dial-up connection afterinstalling SP2, all ofyour shared data are available on the Internet.
Okay, this is just a stupid statement.
Now, other users can startguessing your passwords for administrator and guest and youbasically areno more secure than the first Windows 95 users with an Internet connection - thanks to Service Pack 2.
See above.
How to correct the problem It is not advisable to keep this defective defaultconfiguration. However,the previous environment cannot be restored: Theconfiguration for thefirewall was changed, which does not allow the setting of active or inactive conditions or exceptions for each network adapteranymore. Nowthis only works for network areas.
BZZZZZZT! Wrong again, kiddies. They need to investigate the Advanced tab in the Windows firewall better. I just allowed 3389 on one and only one of my connectoids. In *fact*, on that Advanced tab, the very first chunk of text reads: "Windows firewall is enabled for the selected connections below. To add exceptions for an individual connection, select it, and then click Settings." You can even <gasp!> *pre*-set exceptions for connections on which the firewall is not currently enabled! Neat-OH!
Choose "Windows Firewall" in the in the Windows ControlPanel and thethere the tab "Exceptions". Select "File and PrintServices" and click on"Edit". Now you can see four ports which are used by thefile and printsharing service. To lock the service to the outside and keep it open for theinternal LAN,you have to individually select and change its area withthe respectivebutton.
And the point is?
Our reader Yves Jerschov notified us of another bug: The value for the area set by default "Only for own network (Subnet)"only works, if theInternet Connection Sharing is activated.
My apparently magic computer disagrees with Yves. I do not have ICS on any of my connections. I do, however, have "Only for own network (subnet)" available for each exception. I click the little radio button and SHAZAM! It works. This is ridiculously easy to test. (even when it involves hobbling on crutches from one room to another- only for you, T., do I do these things. ;-) ) 1. Make sure that the XPSP2 box has Remote Desktop enabled. 2. In the Windows Firewall exceptions, ensure that your connection (I recommend having only one active connection during this testing for obvious reasons) allows Remote Desktop (TCP 3389) from "the world". 3. Go to a machine on another subnet and remote in to the XP box. Verify success. 4. Okay, now the fun part. Since you're already remoted into the XP box, change the firewall setting to (subnet) for TCP 3389. 5. Disconnect your session. 6. Attempt to reconnect. Oh, my goodness, it doesn't work anymore. Must be that there firewall thingie that don't werk unless you use ICS on one of your connections. Puhleeze.
If this is notthe case, yourshared data are visible worldwide.
Aside from the fact that their premise is incorrect, this is not quite the case even if it *were* correct.
This error can becorrected by choosing"User defined List" and entering the IP addresses that aresupposed tohave access - the IP addresses of your LAN. A whole rangeof an IP areacan be entered as "192.168.x.0/255.255.255.0", if therespective addressesstart with 192.168.x.
See above.
After these measures, you can be sure to be as safe as youwere with SP1.Great, don't you think?
I think I'd really like to know what these guys consider a testing methodology. I call bullpucky. Laura --------------------------------------------------------------------------- ---------------------------------------------------------------------------
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