Tag Archives: Encryption

How to Rotate Your SSH Keys

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SSH keys are used to secure access to and authenticate authorized users to remote servers. They are stored locally on the client machine and are encrypted using public-key cryptography. These keys are used to encrypt communications between the client and server and provide secure remote access.

When you log into a remote machine, you must provide a valid private key to decrypt the traffic. As long as the private key remains secret, only you can access the server. However, if someone obtains your private key, they can impersonate you on the network.

SSH key rotation helps prevent this type of unauthorized access. It reduces the risk that someone has access to your private key, and helps prevent malicious users from being able to impersonate you on your network.

Most security policies and best practices call for rotating your key files on a periodic basis, ranging from yearly to quarterly, depending on the sensitivity of the data on the system. Such policies go a long way to ensuring the security of authentication credentials and the authentication process for sensitive machines.

There are two ways to rotate your keys: manually, and automatically.

Manually

To manually perform key rotation, you need to generate a new pair of keys. Each time you do this, you create a new key pair. You then upload the public key file to the server you wish to connect to. Once uploaded, the server uses the public key to verify that you are who you say you are.

Automatically

An alternative approach is to use automatic key rotation. With automatic rotation, you don’t need to generate a new key pair each time you change your password. Instead, you simply update the permissions on your existing key file.

The following steps show how to configure automatic rotation.

1. Generate a new keypair

2. Upload the public key to the remote server

3. Configure the remote server to use the new keypair

4. Update the permissions on the old keypair file

5. Delete the old keypair

6. Logout from the remote server

More Information

On Linux systems, use the “man” command to learn more about the following:

    • ssh-keygen command
    • ssh-public-key command
    • upload-ssh-public-key command

The examples should provide options for command parameters and sample command output for your operating system.

For more information about the SSH protocol, you can review the Wikipedia article here.

 

SSL Certificate High-Level Best Practices

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SSL certificates are an essential part of online security. They protect websites against hackers who try to steal information such as credit card numbers and passwords. In addition, they ensure that customers trust the site and its content.

Almost 50% of the top one million websites use HTTPS by default (they redirect inquiries of HTTP pages to URLs with HTTPS). (comodosslstore.com)As such, even pages that don’t deal with confidential data are being deployed using SSL. The underlying certificates to power the encryption are available from a variety of commercial providers, and even the pro-bono resource https://letsencrypt.org. No matter where you get your certificate from, here are a few resources for high-level best practices.

Trust Your Certificate Provider

Since certificates provide the basis for the cryptography for your site, their source is important. You can find a trustworthy list of providers for certificates here. https://www.techradar.com/news/best-ssl-certificate-provider. Beware of commercial providers not found on this list, as some of them may be sketchy at best, or dangerous at worst. Remember, the Let’s Encrypt project above is also highly trusted, even though they are not a commercial firm.

Manage Versions and Algorithms

Make sure you disable SSL and TLS 1.0 on the server. That version has known vulnerabilities. If possible, and there are no impacts on your users, consider removing 1.1 and 1.2 as well. 1.3 fixes a lot of the known issues with the protocol and supports only the known secure algorithms.

In cryptography, cipher suites play an important part in securing connections by enabling encryption at different levels. You shouldn’t be using an old version of a cryptographic protocol if there’s a newer one available; otherwise, you may put your site’s security at risk. Using secure cipher suites that support 128-bit (or more) encryption is crucial for securing sensitive client communications.

Diffie Hellman Key Exchange has been shown to be vulnerable when used for weaker keys; however, there is no known attack against stronger keys such as 2048-bits. Make sure you use the strongest settings possible for your server.

Manage and Maintain Certificate Expiration

As of Sept. 1, 2020, Apple’s Safari browser will no longer trust certificates with validity periods longer than 398 days, and other browsers are likely to follow suit. Reducing validity periods reduces the time period in which compromised or bogus certificates can be exploited. As such, any certificates using retired encryption algorithms or protocols will need to be replaced sooner. (searchsecurity.techtarget.com)

Maintain a spreadsheet or database of your certificate expiration dates for each relevant site. Make sure to check it frequently for expiring certificates to avoid user issues and browser error messages. Even better is to use an application or certificate management platform that alerts you in plenty of time to upcoming certificate expirations – thus, you can plan accordingly. Best of all, if possible, embrace tools and frameworks for automating certificate management and rotation – that makes sure that you are less likely to have expiration issues. Most popular web frameworks now have tools and plugins available to perform this for you.

Protect Your Certificates and Private Keys

Remember that your certificate is not only a basis for cryptography, but is also a source of identification and reputation. As such, you need to make sure that all certificates are stored properly, securely and in trusted locations. Make sure that web users can’t access the private certificate files, and that you have adequate back up and restore processes in place.

Make sure that you also protect the private keys used in certificate generation. Generate them offline, if possible, protect them with strong passwords and store them in a secure location. Generate a new private key for each certificate and each renewal cycle.

Revoke your certificate or keys as quickly as possible if you believe they have been compromised.

Following these best practices will go a long way to making your SSL certificate processes safer and more effective. Doing so protects your users, your reputation and your web sites. Make sure you check back with your certificate provider often, and follow any additional practices they suggest.

 

 

 

 

Interesting Talk on Post Quantum Computing Impacts on Crypto

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If you want to really get some great understanding of how the future of crypto is impacted by quantum computing, there is a fantastic talk embedded in this link. 
 
The talk really turns the high level math and theory of most of these discussions into knowledge you can parse and use. Take an hour and listen to it. I think you will find it most rewarding.
 
If you want to talk about your thoughts on the matter, hit us up on Twitter. (@microsolved)

Beware of Drive Erasure Problems on SSD Drives

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There is a lot of interesting research going on right now with the processes and tools that may be useful in erasing the new solid state drives that many laptops and other systems are using. The traditional methods of magnetic cleansing (degaussing), and even file over-write tools that have been in use now for decades in many organizations, have little to no effect on removing sensitive data on these solid state drives.

Here is a nice article explaining some of the problems.

As described in the article, it seems that many of our current data management and cleansing techniques simply do not apply to these solid state memory-based devices. This makes drive encryption all the more urgent, as these systems are beginning to pop up in many organizations that are starting their hardware refresh processes after delaying them due to economic conditions.

If you are an information security team, or an IT team considering such purchases, please make appropriate cryptography a part of your solution. Many solutions exist by a variety of vendors today with pricing ranging from near zero to the cost of full-scale commercial enterprise implementations in the hundreds of thousands of dollars. Complexity also ranges from trivial and built into the operating system to quite high, depending on centralized management and remote assistance capabilities.

No matter how you to choose to address the problem, the key factor is that you are aware that SSD systems are a different animal with unique challenges versus traditional hard disks. Knowing that will at least put you on the right path toward investigating a solution and updating your processes.

All Your Data Are Belong To Us!

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My last post discussed some tactics for realizing what’s happening under the hood of our browsers when we’re surfing the web, and hopefully generated some thoughts for novice and intermediate users who want to browse the Internet safely. This week, we’re going to look a step beyond that and focus on steps to protect our passwords and data from unwanted visitors.

Passwords are the bane of every system administrator’s existence. Policies are created to secure organizations, but when enforced they cause people to have trouble coming up with (and keeping track of) the multitude of passwords necessary. As a result, people commonly use the same passwords in multiple places. This makes it easier on us as users because we can remember puppy123 a lot easier than we can those passwords that attackers can’t or don’t guess. Doing so also makes it easier on attackers to find a foot hold, and what’s worse is that if they are able to brute force your Yahoo! email account then they now have the password to your online banking, paypal, or insurance company login as well.

Hopefully some of you are thinking to yourselves “Is this guy telling me I shouldn’t be using the same password for everything?” If you are, you get a gold star and you’re half-way toward a solution. For those of you who are not, either you have mastered the password problem or still don’t care- in which case I’ll see you when our Incident Response Team is called to clean up the mess.

To solve this problem, find your favorite password manager (Google will help with this), or use what our team uses- KeePass. This is a fast, light, secure password manager that allows users to sort and store all their passwords under one master password. This enables you to use puppies123 to access your other passwords, which can be copied and pasted so you have no need to memorize those long, complex passwords. KeePass also includes a password generator. This tool lets users decide how long and what characters will make up their passwords. So you’re able to tailor passwords to meet any policy needs (whitespace, special characters, caps, etc) and not have to think about creating something different than the last password created- the tool handles this for you.

In addition to password composition, this tool lets you decide when and if the password should expire so you can force yourself to change this on a regular basis- this is an invaluable feature that helps minimize damage if and when a breach DOES occur. Once passwords are created, they are saved into a database file that is encrypted- so if your computer is lost, stolen, or breeched in some other manner, the attacker will have a harder time getting to your protected password data. There are many of these solutions available for varying price ranges, but I highly recommend KeePass as a free solution that has worked really well for me for quite some time. It’s amazing how nice it is to not have to remember passwords any longer!

Okay, so our passwords are now safe, what about the rest of our files? Local hard drive storage is a great convenience that allows us to save files to our hard drive at will. The downside to this is that upon breaking into our PC an attacker has access to any file within their permission scope, which means a root user can access ALL files on a compromised file system! While full disk encryption is still gaining popularity, “On the fly encryption” products are making their mark by offering strog and flexible encryption tools that create encrypted containers for data that can be accessed when given the appropriate password.

I have used the tool TrueCrypt for years and it has proven to be invaluable in this arena! TrueCrypt allows users to create containers of any size which becomes an encrypted drive that can be accessed once unlocked. After being locked, it is highly unlikely that an attacker will successfully break the encryption to decipher the data, so if you’re using a strong password, your data is as “safe” as it can be. This tool is one of the best out there in that it offers on the fly and total disk encryption, as well as allowing for encryption of individual disk partitions including the partition where Windows is installed (along with pre-boot authentication), and even allows these containers to be hidden at will.

Wow, we’ve gone through a lot together! You’re managing passwords, protecting stored data, learning what’s going on when your browsing the web, and becoming a human intrusion detection/prevention system by recognizing anomalies that occur in regular online activities! Visit next time as I explorer updates with you to round out this series on basic user guidelines.