Category Archives: Uncategorized

Hardening Microsoft Solutions from Attacks

Posted by acbrownit on

Take a minute to go over this post from Dirk-jan Mollema. Go ahead and read it. I’ll wait…

Did you realize how scary that kind of attack is? As an IT guy who specializes in Exchange server and loves studying security, that article scared the snot out of me. Based on my experience with organizations of all sizes I can say with a good bit of authority that almost every Exchange organization out there is probably vulnerable to this attack. Why? Because Exchange is scary to a lot of people and they don’t really know how to harden it effectively. But I also want to use the above attack as a way to illustrate what I feel is the best strategy for hardening a Windows environment (and, really, any environment).

Take this opportunity to look at your Exchange deployment (if you haven’t already moved to Exchange Online) and think about what you can do to protect your environment from this type of thing. In this post, though, I want to focus on Exchange Server and Windows Server hardening techniques in general, rather than this particular vulnerability because with any hardening effort, you want to examine the network as a whole and work downward without focusing on specific vulnerabilities. If you do the opposite, you will invariably end up playing a never ending game of whack-a-mole, trying to stay ahead of a world full of malicious attackers and never really being successful.

The techniques recommended in the Center for Internet Security’s (CIS) Critical Security Controls follow the top-down approach and represent one of the best guides for approaching information security at a technical level.

IT Hardening, a Quick Intro

Hardening is essentially all actions that you take to make an environment more secure. There are many different types of hardening; server hardening, network hardening, physical hardening, procedural hardening, etc. But these all seek to do the same thing, just in different ways.

If you take a close look at the actions the CIS controls recommend, you’ll (hopefully) notice that they seek to secure as much of the environment as possible when you start at control number 1. As you go through the controls, each subsequent control has a more narrow focus. Once you get to control number 5, you will probably have an environment that will stand up against all but the most determined attacks, but you don’t necessarily want to stop there.

The most important best practice in Information Security is the idea of “Defense in Depth”. This technique involves building layers of protection instead of relying on a single security measure to protect your environment. Having a firewall in place is only one “layer” of defense, and is regarded as the broadest level of protection you can have. Anti-virus tools, Intrusion Detection/Prevention tools, and hardening techniques represent additional layers of defense. You want as many layers as you can justify when measuring cost against risk (a much more difficult topic to cover).

Focusing on Windows

One thing that you hear regularly in the IT industry is the argument about what OS people choose to handle their IT. The common argument is that Linux is a more secure OS than Windows, and this is true, up to a point. The reality is that they are simply different approaches to crafting an OS.

Linux tends to be more modular in its approach. If you implement a Linux environment, you would start with the core OS and add features as needed. This approach is good for limiting the attack surface from the start, but it also has a number of drawbacks.

The biggest drawback for Linux is that there is no centralization for support and maintenance. There are lots of different solutions to the same problem, and there isn’t really a single source of support for all solutions, so you have to either have very capable Linux support specialists or handle lots of different vendors. This usually increases the cost of ongoing maintenance and support of the infrastructure. It’s also not uncommon for different Linux-based open source projects to be abandoned for whatever reason, leaving organizations that implemented that solution without support, and once the guy who knows how to use it effectively leaves, you’re left with a very serious problem.

Windows, on the other hand, is a fairly complete package of capabilities for most situations. Windows server has built in solutions that can do most of the work you will want in an IT environment, within some limits. For instance, Windows server doesn’t handle EMail well right out of the box. You have to also implement Exchange server to have a truly effective method of handling email, but with that solution you also gain a very powerful collaboration tool that handles calendaring, contact management, task management, and other features that you can pick and choose from. Microsoft also invests a lot of time and effort in developing training tools and educational resources to ensure that there is a large pool of talent to support their OS and other software solutions. You don’t often have to worry about finding someone who knows how to manage a Windows environment. There are boatloads of MCSAs and MCSEs looking for work almost all the time.

The major drawback with Windows is, of course, security. With all of the features built in, Windows has a very large attack surface compared to Linux. However, with careful planning and implementation, the attack surface of Windows can be decreased very effectively, such that there is virtually no difference between a standard Linux deployment and a hardened Windows environment.

Hardening Windows

Going back to the vulnerability outlined in the link from the start of this article, a single change to a Windows Active Directory environment will eliminate vulnerability: LDAP signing and channel binding. LDAP signing and channel binding are techniques that are used to prevent Man In the Middle attacks from succeeding. I explain the theory behind LDAP signing in more depth in my article on Understanding Digital Certificates. LDAP channel binding is a technique that prevents clients from using portions of authentication attempt against one DC when communicating with a different DC or client. Put simply, it “binds” a client to the entire authentication attempt by requiring clients to present proof that the authentication traffic it’s sending to the server isn’t forged or copied from a different authentication attempt.

Essentially, LDAP signing configures all Active Directory Domain Controllers to that they are verifying that they are actually talking to the server they are supposed to before doing anything. Implementing this is a little difficult, though, as it requires the use of a Certificate Authority to generate and deploy digital certificates, but once digital certificates are installed on Domain Controllers and Member Servers in a Windows Domain, LDAP signing is available (once systems are configured to require it) and becomes a very effective form of security that prevents a wide swatch of attacks that can be performed to gain unauthorized access.

LDAP signing alone won’t prevent all possible attacks in a Windows environment, though, which is why it’s essential to disable features and roles that each server is not using, and taking effective care of remote access to servers. Windows Remote Desktop is one of the most frequently used tools to breach security in a Windows environment, so limiting access to it is essential. As a rule of thumb, only allow System Administrators to access critical Windows Servers and never, *never* allow remote desktop ports through your firewall.

Check your firewalls now, if you have port 3389 allowed to the Internet, it’s only a matter of time before you get attacked and suffer severe consequences. Remote Desktop is *not* meant for allowing remote workers access over the Internet. Implement secure VPNs and practice effective password security policies if you want people to access your IT environment remotely.

Once all unnecessary features and roles are removed or effectively controlled in a Windows environment, build and maintain an effective patch management strategy. Microsoft regularly deploys patches to close security holes before attackers are regularly attacking them. Any patch management plan should make allowances for testing, approving, deploying, and installing Security-related patches as soon as possible.

Next, focus on granting only permissions necessary for workers to accomplish their tasks. This is a difficult practice to implement, because it takes a lot of investigation to determine what permissions each user needs. Many environments grant Administrative permission to users on company owned equipment, which is a horrible, lazy practice that will get your environment owned by a hacker very quickly.

Once you have all of the above security practices in place, you will then want to start focusing on more specific vulnerabilities. As an example method for preventing the attack in the link at the start of this post, changing a simple registry setting will block the attack. But it will not prevent future attacks that may attack vulnerabilities that aren’t well known.

How Does the Cloud Play Into This?

One of the major benefits of using cloud solutions like Exchange Online is that most of the work outlined above has been done already. Microsoft’s cloud servers are stored in highly secure datacenters with many protections against unauthorized access (as opposed to the common tactic of putting the server in a closet in your office). Servers in cloud environments are hardened as much as possible before being put into operation. Security vulnerabilities are usually addressed across the entire cloud environment within hours of discovery, and the servers don’t function with an eye to backwards compatibility, so things like NTLM and SMBv1 are disabled on all systems.

That said, the cloud poses its own security challenges. You must accept the level of security put in place by the cloud provider and will have little to no control over systems in a way that will let you increase security. Furthermore, utilizing a Hybrid-cloud solution (which is extremely common and will be for years to come) presents unique problems involving the interface between two separately controlled environments. Poor security practices in the on-prem side of a hybrid deployment will make the cloud side just as insecure.

You must accept public availability of your data and accept the reality that you don’t control where that data is (for the most part…this issue is slowly changing as cloud environments mature). In addition, your do not offload the responsibility of securing access to the data you store in the cloud. I’ll cover this subject in another post, but for now, understand that while cloud environments build a lot of security into their solutions, you still have a responsibility to make security a priority.

Conclusion (I never can think of a good heading here)

Security in any IT environment is a major challenge that takes careful planning and effective management. Failing to consider security challenges when deploying new solutions will almost always come back to bite you. But, with the right strategy and guidance, it *is* possible to build a secure environment that can withstand the vast majority of attacks.

 

 

Advertisements

Enabling Message Encryption in Office 365

Posted by acbrownit on

As I mentioned in an earlier post, email encryption is a sticky thing. In a perfect world, everyone would have Opportunistic TLS enabled and all mail traffic would be automatically encrypted with STARTTLS encryption, which is a fantastic method of ensuring security of messages “in transit”. But some messages need to be encrypted “at rest” due to security policies or regulations. Unfortunately, researchers have recently discovered some key vulnerabilities in the S/MIME and OpenPGP. These encryption systems have been the most common ways of ensuring message encryption for messages while they are sitting in storage. The EFAIL vulnerabilities allow HTTP formatted messages to be exposed in cleartext by attacking a few weaknesses.

Luckily, Office 365 subscribers can improve the confidentiality of their email by implementing a feature that is already available to all E3 and higher subscriptions or by purchasing licenses for Azure Information Protection and assigning them to users that plan to send messages with confidential information in them. The following is a short How-To on enabling the O365 Message Encryption (OME) system and setting up rules to encrypt messages.

The Steps

To enable and configure OME for secure message delivery, the following steps are necessary:

  1. Subscribe to Azure Information Protection
  2. Activate OME
  3. Create Rules to Encrypt Messages

Details are below.

Subscribe to Azure Information Protection

The Azure Information Protection suite is an add-on subscription for Office 365 that will allow end users to perform a number of very useful functions with their email. It also integrates with SharePoint and OneDrive to act as a Data Loss Prevention tool. With AIP, users can flag messages or files so that they cannot be copied, forwarded, deleted, or a range of other common actions. For email, all messages that have specific classification flags or that meet specific requirements are encrypted and packaged into a locked HTML file that is sent to the recipient as an attachment. When the recipient receives the message, they have to register with Azure to be assigned a key to open the email. The key is tied to their email address and once registered the user can then open the HTML attachment and any future attachments without having to log in to anything.

Again, if you have E3 or higher subscriptions assigned to your users, they don’t need to also have AIP as well. However, each user that will be sending messages with confidential information in them will need either an AIP license or an E3/E5 license to do so. To subscribe to AIP, perform these steps:

  1. Open the Admin portal for Office 365
  2. Go to the Subscriptions list
  3. Click on “Add a Subscription” in the upper right corner
  4. Scroll down to find the Azure Information Protection
  5. Click the Buy Now option and follow the prompts or select the “Start Free Trial” option to get 25 licenses for 30 days to try it out before purchasing
  6. Wait about an hour for the service to be provisioned on your O365 tenant

Once provisioned, you can then move on to the next step in the process.

Activate OME

This part has changed very recently. Prior to early 2018, Activating OME took a lot of Powershell work and waiting for it to function properly. MS changed the method for activating OME to streamline the process and make it easier to work with. Here’s what you have to do:

  1. Open the Settings option in the Admin Portal
  2. Select Services & Add-ins
  3. Find Azure Information Protection in the list of services and click on it
  4. Click the link that says, “Manage Microsoft Azure Information Protection settings” to open a new window
  5. Click on the Activate button under “Rights Management is not activated”
  6. Click Activate in the Window that pops up

Once this is done, you will be able to use AIP’s Client application to tag messages for right’s management in Outlook. There will also be new buttons and options in Outlook Web App that will allow you to encrypt messages. However, the simplest method for encrypting messages is to use an Exchange Online Transport Rule to automatically encrypt messages.

Create Rules to Encrypt Messages

Once OME is activated, you’ll be able to encrypt messages using just the built in, default Rights Management tools, but as I mentioned, it’s much easier to use specific criteria to do the encryption automatically. Follow these stpes:

  1. Open the Exchange Online Admin Portal
  2. Go to Mail Flow
  3. Select Rules
  4. Click on the + and select “Add a New Rule”
  5. In the window that appears, click “More Options” to switch to the advanced rule system
  6. The rule you use can be anything from Encrypting messages flagged as Confidential to using a tag in the subject line. My personal preference is to use subject/body tags. Make your rule look like the below image to use this technique:Encrypt Rule

When set up properly, the end user will receive a message telling them that they have received a secure message. The email will have an HTML file attached that they can open up. They’ll need to register, but once registered they’ll be able to read the email without any other steps required and it will be protected from outside view.

 

 

Data Encryption – How it Works (Part 1)

Posted by acbrownit on


I’ve decided to start a short series of posts on data encryption, which is becoming an increasingly important subject in IT as government regulations and privacy concerns demand ever increasing levels of privacy and security.

In this series, I’ll try to cover the more confusing concepts in encryption, including the three main types of encryption systems used today; Private Key encryption, Public Key Encryption, and SSL/TLS encryption. I will cover how those types of encryption function and vary from one another. I will also get some coverage on one of the most confusing topics in IT security, Public Key Infrastructure. If you haven’t already read by article on Digital Certificates, I would highly recommend doing so before going on to part two of this series, since digital certificates underpin the vast majority of encryption standards today.

What is Encryption?

The goal of encryption is to make any message or information impossible to understand or read without permission. Perfect encryption is (currently) impossible. What I mean by that is there is no way to encrypt data so that it can’t *possibly* be read by someone who isn’t authorized to do so. There are an unlimited number of ways to encrypt data, but some methods are significantly more effective at preventing unauthorized disclosure of data than others.

Encryption Parts

Every encryption system, however, has a few things in common. First, there’s the data. If you don’t have something you want to keep private or secret, there’s no reason to encrypt your data, so no need for encryption. But since we live in a world where secrecy and privacy are occasionally necessary and desirable, we are going to have stuff we want to encrypt Credit card numbers, social security numbers, birth dates, and things like that, for instance, need to be encrypted to prevent people from misusing them. We call this data “Clear-text” because it’s clear what the text says.

The next part is the “encryption algorithm”. Encryption is based very heavily in math, so we have to borrow some mathematical terminology here. In math, an algorithm is all the steps required to reach a conclusion. The algorithm for 1+1 is identified by the + sign, which tells use the step we need to take to get the correct answer to the problem, which is to add the values together. Encryption algorithms can be as simple as adding numbers or so complicated that they require a library of books to explain. The more complicated the algorithm, the more difficult it is (in theory) to “crack” the encryption and expose the original clear-text.

Encryption algorithms also require some value to be added along with the clear-text to generate encrypted data. The extra value is called an encryption “key”. The encryption key has two purposes. First, it allows the encryption algorithm to produce a (theoretically) unique value from the clear-text. Second, it allows people who have permission to read the encrypted data to do so, since knowing what the key is will allow us to decrypt, or reveal, the clear-text (more on this in a bit).

These three pieces put together are used to create a unique “Cipher-text” that will appear to be just gobbledygook to casual inspection. The cipher-text can be given to anyone and whatever it represents will be unknown until the data is “decrypted”. The process we go through to do this is fairly simple. We take the clear-text and the key, enter them as input in the encryption algorithm, and after the whole algorithm is completed with those values, we get a cipher-text. The below image shows this:

Encryption

 

Every encryption algorithm requires the ability to “reverse” or “decrypt” the data, so they all have a different decryption algorithm. For instance, in order to get back to the original value of 1 after adding 1 to it to get 2, you would have to reverse that process by subtracting 1. In this case, we know what input (1) and algorithm (adding) was used to reach the value, so reversing it is easy. We just subtract whatever number we need to get back to the original value (1 in this case). In general, decryption algorithms will take the key and cipher-text as input to the algorithm. Once everything in the algorithm is done, it should result in the original clear-text, as shown below:

Decryption

Simple Examples

Two early examples of encryption come to us from Greek and Roman history. The Skytale was a fairly ingenious encryption tool that used a wooden block of varying size and shape as its key. The clear-text was written (or burned) on a strip of leather that was wrapped around the key on a single side of the key, which was usually hexagonal. The person who was supposed to receive the message had a key of similar shape and size. Wrapping the leather strip around the other key would allow the recipient to receive the message. Using the above terminology, the Clear-text is the message, the key is the block of wood, and the encryption algorithm is wrapping a strip of leather around the key and writing your message along with some fake gobbledygook on all the other sides. Unwrapping the leather from the block gives a cipher-text. Decryption is just wrapping the strip around a similarly shaped and sized block, then look at all sides to see which one makes sense.

One of the more famous encryption algorithms is called the “Caesar Cipher” because it was developed by Julius Caesar during his military conquests to keep his enemies from intercepting his plans. You’ve probably used this algorithm before without knowing it if you ever enjoyed passing notes to friends in school and wanted to keep the other kids (or the teacher) from knowing what the message said if they “intercepted” it.

The Caesar Cipher is fairly simple, but works well for quick, easy encryption. All you do is pick a number between 1 and 26 (or the number of letters in whatever language you’re using). When writing the message, you replace each letter with whatever letter whose space in the alphabet is equal to the number you chose above or below in the alphabet. For instance, “acbrownit” is “bdcspxmju” in a +1 Caesar Cypher. Decrypting the message is a simple matter of reversing that. For a Caesar Cypher, the key is whatever number you pick, the clear-text is the message you want to send, the algorithm is to add the key to the clear-text’s letters, outputting cipher-text.

Key Exchange

For any encryption algorithm to function properly as a way to send messages, you must have a way to ensure that the recipient of the message has the correct key to decrypt the message. Without a key, the recipient will be forced to “crack” the encryption to read the message. So you need to be able to provide that key to the recipient. The process of ensuring that both the sender and recipient have the keys to encrypt and decrypt the message (respectively), a “key exchange” must occur. This is often as simple as telling your friend what number to use with your Caesar cipher.

But what do you do if you need to exchange keys in a public place, surrounded by prying eyes (like, for instance, the Internet)? It becomes much more difficult to exchange keys when needed if there is significant distance between the sender and recipient, which means that the biggest weakness in any encryption standard is making sure that the recipient has the key they need to decrypt the message. If the key can be intercepted easily, the encryption system will fail.

The exchange method used will usually depend on they type of key required for decryption. For instance, in World War II, the German military developed a mechanical encryption device called “Enigma” that was essentially a typewriter, but it changed the letters used when typing out a message with a mechanical series of gears and levels. If you pushed the I button on the keyboard, depending on the key used it would type a J or a P (or whatever). The keys were written down in a large notebook that was given directly to military commanders before they departed on their missions, and the index location of the key assigned to the message was set on the machine itself to encrypt and decrypt messages. The process of creating that key book and handing it to the commander was a key exchange. It was kept secure by ensuring that the only people who had the notebook of keys were people that were allowed to have them. Commanders were ordered to destroy their Enigma machines and accompanying notebooks if capture was likely. The Allies in the war were able to capture some of these machines eventually, which allowed a lot of incredibly smart people a chance to examine them and learn the algorithm used to encrypt data, which ultimately resulted in the Enigma machines becoming useless.

Modern encryption systems utilize a number of different methods for exchanging keys. For example, there are VPN tunnels that utilize “hardware” keys. In these solutions, the networks on each side of the tunnel have a device that is connected to another over the internet through a VPN. Before a connection between each side can be established, a small electronic dongle (about the size of a flash drive) has to be plugged in on each side. The dongle contains the key used to encrypt and decrypt data. The key exchange in this scenario involves having an authorized individual take a key to each site and plug it in. This is a very low-tech kind of key exchange, but is extremely secure because, as long as the individual carrying the keys is trustworthy, we can be sure that no one else has a copy of the key.

There are many other kinds of key exchanges that can occur in an encryption system, but most people don’t realize when a key exchange is even happening on the Internet. Whenever you visit an encrypted website, there are actually two different kinds of key exchange that have to happen before the website is presented. Without the technology to perform those exchanges, entering your credit card to purchase the latest gadget online would be a much more complicated and annoying process.

The Future of Encryption

Encryption techniques have come a long way since the early days of leather straps around wooden blocks. Encryption is also used in more ways, by more people, and for more purposes than you can imagine. Despite the improvements and technological developments that have come along, there is still no such thing as a perfect, unbreakable encryption technique. It’s always possible to decrypt data without permission. All we can do is ensure that the time it takes to “crack” the encryption is prohibitive. AES encryption, for example, can take as long as the universe has existed to crack using brute force techniques (based on the average computer’s processing power). The future, though, will require better, more ingenious encryption systems. Why? Because, theoretically, a sufficiently powerful quantum computer (which doesn’t exist yet) can crack even the strongest encryption in almost no time at all. Rest assured, however, that someone (or a group of someones) will develop a better system that will be much more difficult for quantum computers to crack.

Summing it Up

Encryption is a part of our daily lives, whether we realize it or not. Understanding how it works is becoming more important as time goes on and the need to protect ourselves from prying eyes increases. Hopefully, after reading this article, you can see why encryption is important and what it really does for everyone.

 

Designing Infrastructure High Availability

Posted by acbrownit on

IT people, for some reason, seem to have an affinity towards designing solutions that use “cool” features, even when those features aren’t really necessary. This tendency sometimes leads to good solutions, but a lot of times it ends up creating solutions that fall short of requirements or leave IT infrastructure with significant short-comings in any number of areas. Other times, “cool” features result in over-designed, unnecessarily expensive infrastructure designs.

The “cool” factor is probably most obvious in the realm of High Availability design. And yes, I do realize that with the cloud becoming more common and prevalent in IT there is less need to understand the key architectural decisions needed when designing HA, but there are still plenty of companies that refuse to use the cloud, and for good reason. Cloud solutions are not meant to be one size fits all solutions. They are one size fits most solutions.

High Availability (Also called “HA”) is a complex subject with a lot of variables involved. The complexity is due to the fact that there are multiple levels of HA that can be implemented, from light touch failover to globally replicated, multi-redundant, always on solutions.

High Availability Defined

HA is, put simply, any solution that allows an IT resource (Files, applications, etc) to be accessible at all times, regardless of hardware failure. In an HA designed infrastructure, your files are always available even if the server that normally stores those files breaks for any reason.

HA has also become much more common and inexpensive in recent years, so more people are demanding it. A decade ago, any level of HA involved costs that exponentially exceeded a normal, single server solution. Today, HA is possible for as little as half the cost of a single server (Though, more often, the cost is essentially double the single server cost).

Because of the cost reduction, many companies have started demanding it, and because of the cool factor, a lot of those companies have been spending way too much. Part of why this happens is due to the history of HA in IT.

HA History Lesson

Prior to the development of Virtualization (the technology that allows multiple “Virtual” servers to run on a single physical server), HA was prohibitively expensive and required massive storage arrays, large numbers of servers, and a whole lot of configuration. Then, VMWare implemented a solution called “VMotion” that allowed a Virtual Server to be moved between server hardware immediately at the touch of a button (Called VM High Availability). This signaled a kind of renaissance in High Availability because it allowed servers to survive a hardware failure for a fraction of the cost normally associated with HA. There is a lot more involved in this shift that just VMotion (SANs, cheaper high-speed internet, and similar advancements played a big part), but the shift began about the time VMotion was introduced.

Once companies started realizing they could have servers that were always running, regardless of hardware failures, an unexpected market for high-availability solutions popped up, and software developers started developing better techniques for HA in their products. Why would they care? Because there are a lot of situations where a server solution can stop working properly that aren’t related to hardware failures, and VMotion was only capable of handling HA in the event of hardware failures.

VM HA vs Software HA

The most common mistake I see people making in their HA designs is accepting the assumption that VM-level High Availability is enough. It is most definitely not. Take Exchange server as an example. There are a number of problems that can occur in Exchange that will prevent users from accessing their email. Log drives fill up, forcing database dismount. IIS can fail to function, preventing users from accessing their mailbox. Databases can become corrupted, resulting in a complete shutdown of Exchange until the database can be repaired or restored from backup. VM HA does nothing to help when these situations come up.

This is where the Exchange Database Availability Group (DAG) comes in to play. A DAG involves constantly replication changes to Mailbox Databases to additional Exchange servers (as many of them as you want, but 2-3 is most common). With a DAG in place, any issue that would cause a database to dismount in a single Exchange server will instead result in a Failover, where the database dismounts on one server and mounts on the other server immediately (within a few seconds or less).

The DAG solution alone, however, doesn’t provide full HA for Exchange, because IIS failures will still cause problems, and if there is a hardware failure, you have to change DNS records to point them to the correct server. This is why a Load Balancer is a necessary part of true HA solutions.

Load Balancing

A Load Balancer is a network device that allows users to access two servers with a single IP address. Instead of having to choose which server you talk to, you just talk to the load balancer and it decides which server to direct you to automatically. The server that is chosen depends on a number of factors. Among those is, of course, how many people are already on each server, since the primary purpose of a load balancer is to balance the load between servers more or less equally.

More importantly, though, most load balancers are capable of performing health checks to make sure the servers are responding properly. If a server fails a health check for any reason (for instance, if one server’s not responding to HTTP requests), the load balancer will stop letting users talk to that server, effectively ensuring that whatever failure occurs on the first server doesn’t result in users being unable to access their data.

Costs vs. Benefits

Adding a load balancer to the mix, of course, increases the cost of a solution, but that cost is generally justified by the benefit such a solution provides. Unfortunately, many IT solutions fail to take this fact into account.

If an HA solution requires any kind of manual intervention to fix, the time required for notifying IT staff and getting the switch completed varies heavily, and can be anywhere from 5 minutes to several hours. From an availability perspective, even this small amount of time can have a huge impact, depending on how much money is assumed as “lost” because of a failure. Here comes some math (And not just the Trigonometry involved in this slight tangent).

Math!

The easiest way to determine whether a specific HA solution is worth implementing involves a few simple calculations. First, though, we have to make a couple assumptions, none of which are going to be completely accurate, but are meant to help determine whether an investment like HA is worth making (Managers and CEOs take note)

  1. A critical system that experiences downtime results in the company being completely unable to make money for the period of time that system is down.
  2. The amount of money lost during downtime is equal to whatever percentage of a year the system is down times the amount of annual revenue the organization expects to make in a year.

For instance, if a company’s revenue is $1,000,000 annually, they will make an average of $2 per minute (Rounded up from $1.90), so you can assume that 5 minutes of downtime costs that company about $10 in gross revenue. The cheapest of Load balancers cost about $2,000 and will last about 5 years, so you recoup the cost of the load balancer by saving yourself 200 minutes of downtime. That’s actually less than the amount of time most organizations spend updating a single server. With Software HA in place, updates don’t cause downtime if done properly, so the cost of a load balancer is covered in just being able to keep Exchange running during updates (This isn’t possible with just VM HA). But, of course, that doesn’t cover the cost of the second server (Exchange runs well on a low-end server, so $5000 for server and licenses is about what it would cost). Now imagine if the company makes $10,000,000 in revenue, or think about a company that has revenue of several billion dollars a year. HA becomes a necessity according to these calculations very quickly.

VM HA vs Software HA Cost/Benefit

Realistically, the cost difference between VM HA and Software HA is extremely low for most applications. Everything MS sells has HA capability baked in that can be done for very low costs, now that the Clustering features are included in Windows 2012 Standard. So the costs associated with implementing Software HA vs VM HA are almost always justifiable. Thus, VM HA is rarely the correct solution. And mixing the two is not a good idea. Why? Because it requires twice the storage and network traffic to accomplish, and provides absolutely no additional benefit, other than the fact that VM Replication is kinda cool. Software HA requires 2 copies of the Server to function, and each copy should use a separate server (Separate servers are required for VM HA as well, so only the OS licensing  is an increased cost) to protect against hardware failure of one VM host server.

Know When to Use VM HA

Please note, though, that I am not saying you should never use VM HA. I am saying you shouldn’t use VM HA if software HA is available. You just need to know when to use it and when not to. If software HA isn’t possible (There are plenty of solutions out there with no High Availability capabilities), VM HA is necessary and provides the highest level of high availability for those products. Otherwise, use the software’s own HA capabilities, and you’ll save yourself from lots of headaches.

If You Have a Cisco Firewall, Disable this Feature NOW!!!

Posted by acbrownit on

I don’t often have an opportunity to post a rant in an IT blog (And even less opportunity to create a click-bait headline), but here goes nothing! Cisco’s method of doing ESMTP packet inspection is INCREDIBLY STUPID and you should disable it immediately. Why do I say that? Because when Cisco ASAs/whatever they call them these days are configured to perform packet inspection on ESMTP traffic, the preferred option of doing so is to block the STARTTLS verb entirely.*

In other words, Cisco firewalls are designed to completely disable email encryption in order to inspect email traffic. This is such a stupid method of allowing packet inspection that I can barely find words to explain it. But find them I shall.

You might think that you want your Firewall to inspect your email traffic in order to block malicious email or prevent unauthorized access, or what have you. And in that context, I agree. It’s a useful thing. But knowing that the Firewall is not only inspecting the traffic but also preventing any kind of built in E-Mail encryption from running is rant food for me.

I can just imagine the people at Cisco one day sitting around coming up with ideas on how to implement ESMTP packet inspection. I can imagine some guy saying, “I know, we can design our firewall to function as a Smart Host, so it can receive encrypted emails from our customer’s email servers, decrypt them, inspect them, then communicate with the destination servers and attempt to encrypt the messages from there.” I can then imagine that guy being ignored by the rest of his coworkers once the lazy dork in the room says, “How about we just block the STARTTLS verb?”

Thank you, Cisco engineers, for using the absolute laziest possible method you could find to ensure that all email traffic gets inspected, thereby making certain that your packet inspection needs are met while preventing your clients from using TLS encryption over SMTP.

So, if you have a Cisco firewall and want to have the ability to, you know, encrypt email, make sure you disable ESMTP packet inspection. If that feature is turned on, all your email is completely unencrypted. Barracuda provides a lovely guide on disabling ESMTP inspection. https://www.barracuda.com/support/knowledgebase/50160000000IyefAAC

Cisco tells people to just disable the rule that blocks STARTTLS in email, but that wouldn’t really help their packet inspection much, since everything past the STARTTLS verb is encrypted. If it’s encrypted, it can’t be inspected, other than looking at the traffic and going, “Yep. That’s all gobbledygook. Must be encrypted.” So that’s just a dumb recommendation that doesn’t do anything useful (It also requires a trip to the Cisco CLI, which is a great fun thing). This is why I say disable ESMTP packet inspection on your Cisco Firewall, cause it’s making you less secure.

*For the uninitiated, ESMTP stands for Extended Simple Mail Transfer Protocol, and it’s what every mail server on the Internet today uses to exchange emails with each other. The STARTTLS verb is a command that initiates an encrypted email session, so blocking it prevents encrypted email exchanges entirely. This is a bad thing.

 

Protect Yourself from the WannaCry(pt) Ransomware

Posted by acbrownit on

Well, this has been an exciting weekend for IT guys around the world. Two IT Security folks can say that they saved the world and a lot of people in IT had no weekend. The attack was shut down before it encrypted the world, but there’s a good chance the attack will just be changed and start over. So what can you do to keep your system and data from being compromised by this most recent cyberware attack? If you’ve patched everything up already, or don’t know if you’re patched or vulnerable to this attack (or you just don’t want to deal with Windows updates right now), and you want to be absolutely positive that your computer won’t be affected, disable SMBv1! Like, seriously. You don’t need it. Unless you’re a Luddite.

There are some environments that may still need it (Anyone still using Windows XP and server 2003, antiquated management software, or PoS NAS devices), so if you have a Windows Server environment, run

Set-SmbServerConfiguration –AuditSmb1Access $true

in PowerShell for a bit and watch the SMBServer audit logs for failures.

To disable SMBv1 Server capabilities on your devices, do the following:

Server 2012 and Later

  1. Open Powershell (Click start and enter Powershell in the search bar to open it if you don’t know how to get to it)
  2. Type in this and hit Enter: Remove-WindowsFeature FS-SMB1
  3. Wait a bit for the uninstall process to finish.
  4. Voila! WannaCry can’t spread to this system anymore.

Windows 7, Server 2008/2008R2

  1. Open Powershell (Click start and enter Powershell in the search bar to open it if you don’t know how to get to it)
  2. Type in this (everything on the same line) and hit Enter: Set-ItemProperty -Path “HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters” SMB1 -Type DWORD -Value 0 -Force
  3. Wait a bit for the command to complete.
  4. Voila! WannaCry can’t spread to this system anymore.

Windows 8.1/10

  1. Open Powershell (Click start and enter Powershell in the search bar to open it if you don’t know how to get to it)
  2. Type in this and hit Enter: Disable-WindowsOptionalFeature -Online -FeatureName smb1protocol
  3. Wait a bit for the uninstall process to finish.
  4. Voila! WannaCry can’t spread to this system anymore.

If you’re using Windows Vista…I am so so sorry…But the Windows 7/8 instructions should still work for you.

If you still use Windows XP…stop it. And you’re just going to have to get the patch that MS released for this vulnerability.

An additional step you may want to take is to disable SMBv1’s *client* capabilities on your systems. Running the two commands below (on one each line) will do this for you. This isn’t completely necessary, since the client can’t connect to other systems unless they support SMBv1, so if the SMBv1 server component is disabled above, the SMBv1 client can’t do anything. But, if you want to disable the client piece as well, enter the following commands:

sc.exe config lanmanworkstation depend= bowser/mrxsmb20/nsi
sc.exe config mrxsmb10 start= disabled

Resolving the Internal/External DNS zone Dilemma with Pinpoint DNS

Posted by acbrownit on

Here’s an interesting trick that might help you resolve some of your DNS management woes, particularly if you have a different Public and Private DNS zone in your environment. For instance, you have a domain name of whatever.com externally, but use whatever.local internally. When your DNS is set up like that, all attempts to access systems using the whatever.com domain name will default to using the external, Public IP addresses assigned in that DNS zone. If you want to have internal, Private IP addresses assigned to those systems instead (which is common), you normally have to create an entire zone for whatever.com on your Internal DNS servers and populate it with A records for all the systems that exist in the public DNS zone. This technique, known as Split Horizon DNS or just Split DNS, results in additional administrative burden, since changes to the external DNS zone have to be replicated internally as well, and you have to spend time recreating all the DNS records that are already there. Luckily, there’s a little DNS trick you can use to get past this limitation: Pinpoint DNS.

Pinpoint DNS – What is it?

Put simply, Pinpoint DNS is a technique that utilizes some of the features of DNS to allow you to create a record for a single host name that exists in a different DNS zone than you usually use. For instance, instead of creating an entire Primary zone in your internal DNS for whatever.com, you can create a Pinpoint DNS record for really.whatever.com.

Make it So!

To implement Pinpoint DNS, all you have to do is create a new Primary DNS zone in DNS. Instead of naming the zone whatever.com, name the zone really.whatever.com. Once the zone is created, you can then assign an IP address to the root of that new zone (in Windows, this shows up as the IP being “Same as Parent”). Attempts to connect to really.whatever.com will resolve the root zone IP address, and you will be connected to whatever you set that IP to. So, instead of having an entire internal DNS zone full of DNS A records that you have to fill out, even if you only want an Internal IP on one of them, you can have a DNS zone for the single Internal IP record.

Downsides?

There really aren’t a lot of downsides to this, other than it could confuse people who aren’t familiar with the technique. It does look a little odd to see a lot of Forward Lookup Zones in DNS with only a single record in them, but that’s just aesthetic.

Functionally, as long as the DNS zones you create for Pinpoint records are AD integrated, there aren’t any technical downsides to this technique, but if you have a large, distributed DNS infrastructure that *isn’t* AD integrated, this technique will greatly increase administrative burden, since you have to create replication configurations for each Pinpoint record. If you run a DNS environment that isn’t part of Active Directory, Pinpoint DNS isn’t a good solution, because it increases the burden more than managing split horizon DNS.

DNS is a very light-weight protocol (having been designed in the late 70s), so replication traffic increases caused by having multiple Forward Lookup Zones is generally not an issue here.

Windows How To

To implement this, do the following:

  1. Open DNS Management (preferably a Domain Controller)
  2. Expand the DNS server that’s listed
  3. Right Click the Forward Lookup Zones entry and select New Zone to open the new zone wizard. Hit Next when the wizard opens.
  4. Make sure Primary DNS Zone is selected, and that the AD Integration option is checked. Click Next.
  5. Select the option to replication to all DCs in the Forest (particularly if you are in a multi-domain Forest. It’s not necessary for single domain forests, but it’s a good idea to set this anyway, in case that ever changes). Click Next.
  6. Enter the name of the zone. This will be the host name you’re assigning an IP to, so really.whatever.com for the previous example. Click Next.
  7. Select the option to only allow secure updates (It’s the default, anyway). Click Next, then Finish to finalize the wizard and create the zone.
  8. Expand your Forward Lookup Zones and you’ll see the zone there, like below:PinpointDNSZone
  9. Right Click the new Zone, select New Host (A or AAAA).
  10. In the wizard that appears, *leave the host name blank*. This is important, since it is the key part of Pinpoint DNS. An empty host name assigns the A record to the root domain.
  11. Enter the IP address you want to point to in the IP address field, then click Add Host. Your record should look like the one below:PinpointDNSRecord
  12. Verify the new record appears in the really.whatever.com zone, and shows as (Same as Parent).

Once that’s done, the next time you ping really.whatever.com (after running “ipconfig /flushdns” to clear your DNS cache, of course), you’ll receive the Internal IP address you assigned to the Pinpoint zone, and the rest of your external DNS records will remain managed by external DNS servers.