Showing posts with label lock down. Show all posts
Showing posts with label lock down. Show all posts

Sunday, 25 September 2011

Configuring default FTP logon domain

If you’re still stuck in the dark insecure age of the internet and using FTP, you may want users to login to your FTP site using their domain credentials.

By default, the FTP service will use the local user database on the server itself (unless you enter your username in the domain\username format), you can however configure IIS to use a domain by default.

Take caution in doing this though, if you’ve ever put an FTP server on the internet, take a look at the event logs, it will have a ton of brute force attacks on it within minutes.
By default FTP will be trying to authenticate locally, which is a much smaller attack surface (fewer users) as soon as you point it at your domain, it’s going to have a much larger attack surface (more users)

You need to make sure you don’t have any accounts such as “test” or users like “mary” with passwords of “password” or any dictionary word at all. You should also tie the FTP site down to the specific users that need access, so if an account does get compromised it can’t be used to put data in the FTP directory.
With the above in mind, use an elevated command prompt to run the following on the FTP server

adsutil set msftpsvc/DefaultLogonDomain "YourDomainName"
This will set the default logon domain for all FTP sites.

Friday, 13 May 2011

Using a PAC file to set proxy settings

There are many ways to configure proxy settings, via a GPO, via a build, or an application.

Proxy settings can cause issues for mobile users if they use their device away from the corporate LAN as the proxy server will not be reachable, this will render the internet browser unusable (unless of course Direct Access has been implemented)

There are many solutions to this problem, some common ones are:
1. Teach users to enable and disable proxy settings, This is not the most elegant solution, is likely to cause a fair amount of support calls, and also means proxy settings cannot be enforced.

2. Run a 3rd party app that users can click on and select proxy on or proxy off. Im not a fan of these types of applications that sit there and use up resources for no real reason.

3. Run a login script that sets the proxy setting if you are connected to the corporate LAN, and doesn’t if you are not. This is a long winded way of doing it, and is not 100% effective.

In my opinion, the most effective and efficient way of configuring proxy settings is to use a proxy auto config file (PAC)
A PAC file contains a JavaScript function "FindProxyForURL(url, host)". This function returns a string with one or more access method specifications. These specifications cause the user agent to use a particular proxy server or to connect directly

.
You configure your browser (works in all popular browsers) to use a script to configure proxy settings, this setting remains in place permantly. If the PAC file is placed on a web server accessible only within the corporate LAN, if the user is away from the LAN, the config file is not found, so therefore a proxy is not used.


When the user is within the LAN, the file is found, and proxy settings configured.
Some say that a login script can achieve this too, however the login script requires you to login to take effect.


Take a scenario where a user is in the office, closes the lid on his or her laptop, gets on the train then opens the lid, and connects via 3G.
If proxy settings were configured with a login script, the office proxy settings would still be present unless the user logged off and on again.
With a PAC method in place, the browser looks for the settings each time a page is requested, therefore it would fail to find the config file and connect directly.

Below is an example PAC file which can be modified to suit your needs. This could be further extended to look at the current IP of the client, and return a different proxy depending on where the client is. Eg if the client is within an IP range which is associated with the Paris office, the Paris proxy would be returned, or if the client is on a New York IP range, the New York proxy would be returned.


function FindProxyForURL(url, host)
 {
        
        // Direct connections to Hosts
         if (isPlainHostName(host) ||
         (host == "127.0.0.1") ||
         (host == "www.a-whole-domain.com") ||
         (shExpMatch(host, "*.a-entire-domain.com")) ||
         (shExpMatch(host, "10.20.30.*"))) {
           return "DIRECT"
         } else {
           return "PROXY proxy-server.domain.com:8080"
         }
 }



Within this file, access to the IP range 10.20.30.0 - 10.20.30.255 would be accessed directly (bypassing the proxy) aswell as the domain www.a-whole-domain.com. anything under the domain a-entire.domain.com would also bypass the proxy. everything else will be directed at the proxy server "proxy-server.domain.com" on port 8080.
Add additional sites to the proxy bypass list by copying an existing line and pasting it below.


Although a WPAD file could also offer similar functionality, in my experience a PAC file is much more flexible and will enable changes to take effect instantly.

Monday, 4 October 2010

Implementing AppLocker – some important steps before you start!

AppLocker is a feature within Windows 7 and Server 2008 R2 which uses rules and properties of files to provide access control for applications.
In an environment where you want to prevent the use of certain applications, or even to deny all applications and only allow the applications you name, AppLocker is the solution for you.


Before you get started, there are some pre requisites which aren’t so obvious. Without configuring the prerequisites detailed in this article, although your be able to configure AppLocker policy’s, and a gpresult will show them as being applied, they will not be.

The first step is to enable AppLocker Rule enforcement. To do this, edit the group policy object which you wish to use to apply the AppLocker policys, and navigate to

Computer Configuration | Policies | Windows Settings | Security Settings | Application Control Policies | Applocker

Select “Configure rule enforcement



Select all three configured boxes (ensuring that enforce rules is selected from the drop down boxes) and click ok. This now means any policies you put in place will be applied for executable applications, windows installers and scripts.




The next stage is to ensure the “application identity service” is running
This can be done manually on all your workstations, as part of a generic build or via group policy preferences. Group policy is by far the most effective way of doing this so it is detailed here.


Edit the group policy object which you want to use to configure the service, this GPO must apply to all computers you wish to have AppLocker policies applied on

Services can be configured by using Group Policy Preferences, to configure this navigate to:
Computer Configuration | Preferences | Control Panel Settings | Services
Right click ion services and select New | Service

Modify the start-up to be "Automatic" and browse for the service named “Application Identity” ensure the service action is “Start Service” then click ok



Because these are all machine policies, the workstations may need to be rebooted twice for them to take effect.