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Configuring Splunk Universal Forwarder on Forefront TMG 2010

Aggregating logged data from security devices such as the Forefront Threat Management Gateway (TMG) 2010 firewall is a top priority for many security engineers. Forefront TMG and its predecessor, ISA Server, have always lacked an integrated facility to forward logged data to an external event management system. Often the administrator will have to devise an elaborate process that consists of batch files or scripts that collect firewall and web proxy logs and copy them to another location where they can be consumed. In the past I’ve demonstrated how third-party utilities can convert firewall log data to the syslog format as well.

Splunk is one of the more popular log management systems in use today, and to make it easier to get Forefront TMG log data in to Splunk we can use the Splunk Universal Forwarder. The Universal Forwarder is a utility that installs on the Forefront TMG firewall and monitors the folder containing W3C formatted text log files. The Universal Forwarder has a small footprint and consumes few resources, making it the ideal method to collect Forefront TMG log data and deliver it to the Splunk indexing server for analysis and archiving. The Splunk Universal Forwarder can be downloaded here.

Configuring Forefront TMG 2010

Before installing the Universal Forwarder, the Forefront TMG firewall must be configured to log to text file format. To change the log file format, open the Forefront TMG management console and highlight the Logs & Reports node in the navigation tree, select the Logging tab in the center console window, and then click Configure Firewall Logging in the Tasks pane on the right.

Select the option to log to File and choose the W3C extended log file format from the drop down box below. Repeat these steps to configure web proxy logging.

When the option to log to text file format is chosen, native Forefront TMG reports cannot be generated and access to historical log data in the Forefront TMG management console is no longer possible. Clicking Ok will generate the following warning message:

Reports cannot be generated with the currently selected logging
method. To generate reports, use logging to SQL Server Express
databases (on the local server).

An access rule must be created to allow the Splunk Universal Forwarder to communicate with the Splunk indexing server. The source will be the local host network, the destination will be the Splunk indexing server, and the protocol will be TCP 9997 (outbound), which is the default port used by the Splunk Universal Forwarder.

Configuring Splunk Universal Forwarder

Next, install the Splunk Universal Forwarder on the Forefront TMG firewall. When prompted, enter the hostname, FQDN, or IP address of your indexing server and specify a TCP port to use (the default is TCP port 9997).

Select the option to forward Local Data Only.

The Forefront TMG firewall will create new text log files each day and store them in the specified log files folder. Specify a Path to monitor by clicking Directory… and selecting C:\Program Files\Microsoft Forefront Threat Management Gateway\Logs (or the path where your log files are stored, if different from the default).

Configure Splunk Indexing Server

Once the installation is complete, open the Splunk Manager and click Forwarding and receiving.

Click the Add new link next to Configure receiving.

Configure the indexing server to Listen on this port and enter 9997.

Once you’ve configured Splunk to receive data from the forwarder, Forefront TMG firewall and web proxy log data should appear on the indexing server.

Security Configuration Wizard for Forefront TMG 2010 and Windows Server 2008 R2 SP1

Security hardening and attack surface reduction is an important step in preparing a Forefront TMG 2010 firewall. To accomplish this task, the tool of choice is the Security Configuration Wizard (SCW). In one of my ISAserver.org articles I demonstrated how to use this tool to properly configure the underlying operating system to support the Forefront TMG 2010 firewall role. Since the native Windows SCW does not include support for the Forefront TMG role, the TMGRolesForSCW.exe utility included in the Forefront TMG Tools and SDK is required. This tool was released prior to service pack 1 for Windows Server 2008 R2 and does not include a template that works correctly out of the box. When you attempt to register the Windows Server 2008 R2 template on a system with SP1 installed you will receive the following error:

Command completed with error.
The parameter is incorrect.
Please check log file(s) under the following directory: 
%windir%\security\msscw\logs

To resolve this issue, create a copy of the template file SCW_TMG_W2K8R2_SP0.xml and name it SCW_TMG_W2K8R2_SP1.xml. Open this file with any text editor and navigate to the SCWKBRegistrationInfo node (line 2). Change the value of ServicePackMajorVersion from “0” to “1” and save the file. Register the template using the following command:

scwcmd register /kbname:TMG /kbfile:scw_tmg_w2k8r2_sp1.xml

Continue using the SCW to configure and apply a security template to your TMG firewall following the instructions in my ISAserver.org article.

Fwengmon.exe and Forefront Threat Management Gateway (TMG) 2010

November 2, 2010 2 comments

For engineers performing advanced troubleshooting on TMG, you have likely noticed that fwengmon.exe, a utility that you used with previous versions of ISA, no longer functions with TMG.

Not to worry! This detailed information is readily accessible using netsh.exe in the tmg context. The following is a list of common commands and their fwengmon.exe equivalents (where applicable):

To view creation objects, active sessions, NLB hook rules, NLB server assigned ranges, and dynamic and persistent allowed ranges:

netsh tmg show all

To view connections only (fwengmon.exe /session or /s):

netsh tmg show connections

To view detailed information about a specific connection (fwengmon.exe /s <ID>):

netsh tmg show connections <connection_number>

To view firewall creation elements (fwengmon.exe /creations or /c):

netsh tmg show creations

Note: You can sort and filter output from show connections or show creations by source IP address, source port, destination IP address, destination port, or protocol using the sort and filter parameters (fwengmon.exe /organize or /o, or fwengnmon.exe /filter or /f). You can also limit the number of connections or creations displayed using the display parameter. Type netsh tmg show connections ? or netsh tmg show creations ? for more information.

To show NLB hook rules (fwengmon.exe /querynlb or /n):

netsh tmg show nlbhookrules

To view packets held in kernel mode:

netsh tmg show holdpackets

To view packets held in user mode:

netsh tmg show usermodepackets

To view global firewall engine driver settings:

netsh tmg show global

To specify a temporary address range to exempt from firewall filtering (fwengmon.exe /allow or /a):

netsh tmg add allowedrange <beginning_ip> <ending_ip>

To specify a permanent address range to exempt from firewall filtering (fwengmon.exe /allow or /a):

netsh tmg add allowedrange <beginning_ip> <ending_ip> persistent

Note: netsh tmg add allowedrange allows all traffic to and from hosts within the IP address range specified to bypass stateful firewall inspection completely. It should be used for troubleshooting purposes only.

To delete a temporary address range (fwengmon.exe /noallow):

netsh tmg delete allowedrange id=<id>

To delete a permanent address range (fwengmon.exe /noallow):

netsh tmg delete allowedrange id=<id> persistent

How to Determine TMG Version

October 11, 2010 Comments off

Recently Tarek Majdalani, one of my fellow Forefront Edge Security MVPs, published an informative article detailing several ways to determine which version of TMG is installed. One additional method you can use to determine the version of TMG you are running is by using COM. The VBScript code looks like this:

Option Explicit

Dim Root, Server

Set Root = CreateObject("FPC.Root")
Set Server = Root.GetContainingServer

WScript.Echo Server.ProductVersion

Set Server = Nothing
Set Root = Nothing

Copy the code above and save it in a file with a .vbs extension, or download the script file here.

You can execute the script from the command line using cscript.exe using the following syntax:

cscript.exe <path_to_script_file>

The output of the command includes the TMG version and build number information.

You can also double-click the script file in the GUI and a Windows message box will appear with the TMG version and build number information.

Changing the WebSpy Vantage Scheduled Task Recurrence Interval

July 16, 2010 1 comment

There are many third-party reporting tools available today that can aggregate log data for analysis, reporting, and event correlation. One of my favorites for Microsoft Forefront Threat Management Gateway (TMG) 2010 is WebSpy Vantage. Vantage uses its own data stores (called storage), so before you can view logged data or generate reports, you must first import data from your current TMG logging repository (SQL or text file) in to Vantage storage. Once this data has been imported you can do pretty much whatever you want with it after that.

When you create a task to automate the import of log data, you will notice that the Recurrence options are limited to None, Daily, Weekly, and Monthly.

What if you’d like to import the data more frequently than daily? You could create another daily task and schedule that to run daily at a different time, but fortunately there’s an easier way. Since WebSpy Vantage leverages the Windows Task Scheduler, we can use the schtasks.exe command line tool to alter the schedule to run more frequently.

To accomplish this, first copy the Key for the scheduled task you wish to modify.

Next, open a command prompt. The syntax for the command when using Vantage Ultimate is:

schtasks /change /tn “Vantage Ultimate […key…]” /ri <interval_in_minutes>

For example, if we want to alter the task above to run every 4 hours, the command would look like this:

schtasks /change /tn “Vantage Ultimate [87bfae7f-a476-4e4e-8f04-d801d58ca736]” /ri 240

You can verify the new task settings by entering the following command:

schtasks /query /tn “Vantage Ultimate [87bfae7f-a476-4e4e-8f04-d801d58ca736]” /v /fo list

The output will look similar to this:

With schtasks.exe, the interval range in minutes is 1-599940.

Creating User Mode Process Dumps in Microsoft Forefront Threat Management Gateway (TMG) 2010

May 1, 2010 Comments off

In a recent post on his blog, Yuri Diogenes shared with us how to create a manual dump of the wspsrv.exe process in TMG by using the Windows Task Manager. This is tremendously helpful in many situations, but there are scenarios that require more flexibility. For this I use procdump.exe from Sysinternals. To create a dump of a user mode process, enter the following command:

procdump <process>

For example, creating a dump of the wspsrv.exe process would look like this:

procdump wspsrv

This will immediately generate a dump file called wspsrv.dmp.

Procdump provides additional flexibility by allowing you to trigger a dump based on specific thresholds. This is extremely useful when troubleshooting intermittent high CPU utilization issues with TMG. For example, if you wanted to create a dump of the wspsrv.exe process when CPU utilization reaches 90% for more than 5 seconds, enter the following command:

procdump –c 90 –s 5 c:\wspsrv.dmp

When CPU utilization stays at or above 90% for more than 5 seconds, a user mode process dump will be generated and saved in the file c:\wspsrv.dmp. This can be beneficial in situations where high CPU utilization prevents you from using the mouse or typing commands at the command prompt. Automating the task of capturing dumps based on triggers also frees the administrator from having to be at the console when the symptom occurs. Additional command line switches allow you to create multiple dumps, increasing your chances of collecting accurate data for troubleshooting.

Configuring Syslog on ISA and TMG with Splunk Log Management

[Updated July 26, 2011: You can also use the Splunk Universal Forwarder to deliver Microsoft ISA Server and Forefront TMG 2010 log files to a Splunk indexing server. More details here.]

In a recent ISAServer.org article I wrote about the enhancements made to the logging infrastructure in Microsoft Forefront Threat Management Gateway (TMG) 2010. With regard to logging, one commonly requested feature for ISA and TMG is integration with syslog. Many organizations collect log data from numerous systems and network devices in their environment and aggregate that data in a central repository. This makes auditing, reporting, and event correlation with multiple systems much easier.

Although ISA and TMG do not support syslog natively, this functionality is available by using a free third-party utility. Snare Epilog for Windows is a tool that takes data from ISA and TMG log files and exports them to a syslog server such as Splunk.

Before installing Snare Epilog for Windows you will need to change the Firewall and Web Proxy logging properties to use the text file format. Be advised that when you do this, you will no longer be able to view historical log data in the ISA or TMG management console.

Configure Logging

To configure TMG for text file logging, open the management console and highlight Logs & Reports in the console tree, then select the Logging tab.

To configure ISA for text file logging, open the management console and highlight Monitoring in the console tree, then select the Logging tab.

For both ISA and TMG, click Configure Firewall Logging or Configure Web Proxy Logging in the Tasks pane.

Select the File option and choose W3C Extended Log File Format. Do the same for Web Proxy Logging.

Configure Syslog Access Rule

To allow ISA or TMG to communicate with a remote syslog server, an access rule must be created that allows syslog traffic from the Local Host to the syslog server. This will require a new custom protocol to support syslog (UDP 514) with a direction of send.

Once completed, the access rule should look like this.

Installing and Configuring Snare Epilog for Windows

Download and install Snare Epilog for Windows on the ISA or TMG firewall. For ISA or TMG arrays, install Epilog on each array member. Installation is simple and straightforward – just accept the defaults until completed.

To configure Epilog to send log data to a remote syslog server, such as a Splunk log management server, navigate to Start/All Programs/InterSect Alliance and select Epilog for Windows. On the left side, click Log Configuration.

Click Add, and then in the drop-down box, select Microsoft ISA Firewall Logs.

In the Log File or Directory field, enter the location of the firewall logs. For TMG, the default log folder is C:\Program Files\Microsoft Forefront Threat Management Gateway\Logs. For ISA, the default log folder is C:\Program Files\Microsoft ISA Server\ISALogs. In the Log Name Format: field, enter *FWS*.w3c. Click Change Configuration when finished.

To add Web Proxy log files, repeat the steps above, selecting Microsoft ISA Web Logs as the log type and specifying *WEB*.w3c for the log name format.

Note: For demonstration purposes I have used the default location for the ISA and TMG log files. Best practices dictate that the log files be located on a separate physical disk from the system partition, however.

Click Network Configuration.

Enter the IP address and destination port for your syslog server, and then click Change Configuration.

After completing the log and network configuration, click Apply the Latest Audit Configuration to complete the process.

To confirm that Epilog for Windows is configured correctly, click Latest Events to view the current events. Epilog will display any monitored log information.

If everything is configured correctly and working properly, you should now see ISA or TMG log data in your syslog console. If you do not see log data in your syslog console, you may need to restart the Epilog service on the ISA or TMG firewall.