Network Zoning (The Zone)

I decided to start a series on Network Zoning after seeing too many “you need to zone your network” articles and best practice guidelines that never give any aide to the reader on HOW to go about this other than segregate your network or firewall off the servers. Before you attempt this, make sure you understand the limitations of your infrastructure and the concepts outlined below.

In this series, a ‘Zone’ will be the LAN segment set aside for a specific function or IP Range. This zone will route or switch to a firewall-like interface which will provide the “networking” part of the puzzle between the various zones. Depending on the ruleset, data from one zone may or may not be transported to another zone.

Make sure you’re familiar with TCP/IP, Networking, VLANs, IP Addresssing, and subnets; you don’t need to be an expert to proceed. The examples, configurations, and how-to will assume you’re working with Cisco equipment. If you need help with other equipment, you’re welcome to drop me a line.

In this example, the zoning will be accomplished by assigning like-resources to a specific VLAN and having these VLANs end on a router/firewall interface whereBasic Network Zoning access decisions can be made in accordance with local Security Policies and Practices. 

First thing’s first.

Zoning implies some grouping of computing resources. This grouping could be by location, function, purpose, access type, subnet, etc. Because this is my how-to, I’m going to zone according to functional area and subnet. Take a look at this basic diagram where users, administrators, application servers, and sensitive data servers are zoned off and tie back to a firewall.

Functional zoning is very beneficial once the firewall side comes into play because the access rules and restrictions should be largely similar across the specific zone. All the servers shouldn’t need Y! Instant Messenger access but the Desktop Users might run The Weather Channel on their desktop. Zoning like resources makes management of the firewalling and routing simpler over-time as well, because the zoned areas can be extended without re-inventing the wheel.

Once you know how you want to group the resources, it is important to describe and qualify what is unique and different about each grouping. This ensures that your groups don’t overlap as well as preserves the groupings going forward. Depending on your experience with firewalling and routing, at this point you may want to begin clarifying what each zone can and cannot access, for instance - the Sensitive Data Servers DO NOT surf the web or have access to email.

The example here assumes the subnets of these groups allows for grouping or summarization, this may or may not be the case in your grouping but if you have the options it does simplify things in other areas as well. For my example I have allocated 256 IP Addresses to each of the two server zones along with the administrator zone and I have allocated 1024 IP Addresses for the user zone:

• Zone - APPS = 10.0.0.0/24 (10.0.0.0 - 10.0.0.255) [256 Server IP Addresses]
  • Description: Zone dedicated to application servers and services, no end-users and no sensitive customer data
  • Examples: Intranet server, Email server, File server
• Zone - SENSITIVE = 10.0.1.0/24 (10.0.1.0 - 10.0.1.255) [256 Server IP Addresses]
  • Description: Zone dedicated to servers that contain sensitive customer data (could also be employee data)
  • Examples: Oracle database server
• Zone - SYSADMIN = 10.0.2.0/24 (10.0.2.0 - 10.0.2.255) [256 System Administrator IP Addresses]
  • Description: Zone dedicated to privileged administrators of systems, applications, or infrastructure, requires extra access to servers, network elements, etc.
  • Examples: Network Management Team, Firewall Administrators, Database Administrators, etc.
• Zone - USERS = 10.0.3.0/22 (10.0.3.0 - 10.0.6.255 [1,024 Desktop User IP Addresses
  • Description: Zone dedicated to the general user base
  • Example: Average Joe user

These examples and zones will  not apply to every organization. These are hypotethical and designed to get your imagination flowing. The key ingredient is being able to combine 'like users' and 'like access'. The zone members will be placed into their own VLAN and will not be able to talk to devices outside their VLAN unless a router or firewall allows them to do so. In the example above, this VLAN configuration will allow the use of routed VLAN interfaces and switched VLAN interfaces. The difference between routed and switched interfaces being: switched interfaces only talk to similar switched interfaces (ZONE-USERS talks to ZONE-USERS over switched interface while ZONE-USERS cannot talk to ZONE-APPS without passing through a routed interface).

There is one more zone to introduce, that I have come to rely heavily on, ZONE-NETCORE. If you think about it, you've zoned the users, the applications, and the servers. What about the network?

• Zone - NETCORE = 10.255.0.0/24 (10.255.0.0 - 10.255.0.255) [256 Network Core IP Addresses]
  • Description: Zone dedicated to network interface on routers to facilitate core communications and isolate zones
  • Examples: each router has an interface on this Zone

The ZONE-NETCORE is not required, but it serves to isolate the VLANs from one-another across a core or the network, without this zone each VLAN/ aka Zone must come all the way back to the firewall, as indicated in the basic diagram. This approach creates communities that are aggregated and connected via conduits, as depicted here. Note each zone is self-contained and isolated from other zones before reaching the firewall.

Now we have zones defined and understand basic functionality inside the zones. How are the VLANs setup? What security do we need for each zone and how is that accomplished?

Stay tuned…

Leaking at the speed of light

I read in disbelief: “Details are emerging of security leaks at the White House which have shut down an internet spying operation that had successfully cracked al-Qaeda’s computers… Within an hour of the publicity al-Qaeda’s intranet was taken offline.”

An organization formed to study and report on terrorist activities, Site Institute, accessed al-Qaeda’s intranet and obtained the recent Bin Laden video before it was released to the press. Somehow screenshots of this intranet found their way to Fox News and other news organizations and shortly thereafter the intranet was shutdown. Way to go!!!

“Techniques that took years to develop are now ineffective and worthless,” Rita Katz, Site’s founder, told the Washington Post. “The US government was responsible for the leak of this document.”  — VNUNet

Newsflash: the bad guys have cable and satellite tv too!

iPhone: Cracking the Dream

Moore is the man. I have lost count of the number of times I have uttered those words. I am a huge fan of Metasploit and the framework it provides is unrivaled. I recently wrote about the hacking platform that an iPhone provides, noting it would be a great tool for a bad guy. Moore is a man on a mission…

HDM has an updated ARM hack that promises to take over all iPhones, but for now takes over modified iPhones. Techie speak here, English here.

We can store our shellcode at offset 0×12C and patch the return value with 0×0006b400 + 0xA4 to return back to it. A quick test, by setting offset 0×12C to 0xffffffff (an invalid instruction), demonstrates that this works. We have successfully exploited the iPhone libtiff vulnerability using a return-to-libc back to memcpy().

Modified iPhones make this stack/heap overflow easier to accomplish, while “native” iPhones require some additional manipulation to consistently produce the exploit.

This attack exploits libtiff (TIFF Image Library in OS X) by writing to the stack a memory location that is writable and then execute that code (gross oversimplification). The manner in which this exploit is delivered opens the door for other exploits and shows how research to “modify” the iPhone for freedom from AT&T can be used to 0wn the iPhone!

Metasploit continues to be a great tool for “evaluating” security of just about anything:

While using a hex editor to write this exploit is possible, the Metasploit Framework provides a much easier method of testing different contents for the TIFF file. A working exploit for this flaw (successfully tested on 1.00 and 1.02 firmwares) can be found in the development version of the Metasploit Framework (available via Subversion).

Governator Terminates Data Protection Law

I love the Terminator movies, Arnold is great in them. (No flames please!)

He apparently has some savvy advisers who have flexed their political and technical muscle in a way similar to Arnold’s physical: see Governor Kills California Data Protection Law. I find this line of logic amazing, especially given that Arnold is supposed to be some dumb jock elected Governor of California:

However, the current version of the bill, Schwarzenegger said, “attempts to legislate in an area where the marketplace has already assigned responsibilities and liabilities that provide for the protection of consumers. In addition, the Payment Card Industry has already established minimum data security standards when storing, processing, or transmitting credit or debit cardholder information.”

The governor argued that “the industry”—presumably a reference to credit card companies and the PCI Council—is in a better position to know what is realistic and reasonable for credit card security.” Also, he said, signing such a bill could actually create a conflict.

“This industry has the contractual ability to mandate the use of these standards, and is in a superior position to ensure that these standards keep up with changes in technology and the marketplace,” he said. “This measure creates the potential for California law to be in conflict with private sector data security standards.”   –eWeek / Security Focus

I know security experts that couldn’t come up with the logic behind that statement. I’m not a fan of legislating everything and I think what the Payment Card Industry is doing with Data Security is great, if significantly late to the game.

The major problem I have with the PCI DSS requirements is the subjectiveness of assessment, audit, and enforcement. If the PCI DSS actually had teeth, then the breaches we read about would be less likely to occur because of the financial impact associated, For instance, when a merchant can’t process credit cards due to noncompliance with the PCI DSS, they would signficantly more interested in complying with PCI DSS.

Go Arnold!!!

BlackBerry: International Exposure?

George Gardiner wrote an editorial post on Oct 5th for IT Week noting the potential security / legal issues surrounding RIM’s Canadian-based data center that receives nearly all BlackBerry traffic to/from BlackBerry handhelds.

Having worked in the telecommunications industry, it came as no surprise that to learn that nearly all customers and carriers accessing or providing BlackBerry services are routed through RIM’s Canadian data center. George’s concerns centered around differences in privacy, security, and intercept laws between US, Canada, UK, EU, etc. (Original here, cached here)

This concern comes in stark contrast to the security and privacy offered by the BlackBerry handhelds. They almost all offer hardware-based 3DES encryption or AES encryption (AES is the current defacto), each handheld can encrypt ALL the content on the BlackBerry. Your data communications channel is encrypted back to RIM over your carrier’s network and your carrier likely has a dedicated data circuit connecting them directly to RIM’s data center.

The article suggests your data may be at additional exposure risk because it lives in a central point outside the control of your phone carrier’s control or your direct control and likely your country. Newsflash: Because your data is now in Canada it may not be as protected from interception as protections available in the US, UK, or EU. I read some interesting forum postings about the article, so I thought I’d pile on to the blog side of it.