Sunday, May 20, 2018

Online threats, risks, and mitigations

Have you wondered exactly how security risks arise on the Internet and what you can do about them? Here is a short summary of the more common threats, the risks that they cause, and mitigations for those risks.

For a bit more how-to information, see my previous blog post: Core security advice for general users

General notes:
  • Most of the risks listed below can lead to theft of data, identity theft, financial theft, impersonation, takeover of your accounts, your dog running away, etc. 
  • "Long, random, unique passwords": This means that each password is truly random, at least, say, 25 characters long, and is never used for more than one site. The only way to do this is to use a password manager. Use a stand-alone password manager, not one built into your browser. 
  • "Zero knowledge" service: The service is designed so that your data is encrypted on your device before it leaves the device for the cloud, and the encryption key used is never sent to the cloud. In this way, if your (encrypted) files in the cloud are stolen, they will be unreadable by the attacker. 
  • Multi-factor authentication (MFA): These are the common second-factor options, from most secure to least secure: 
  1. Cryptographically strong, e.g., U2F 
  2. TOTP (e.g., Google Authenticator, Authy), HOTP 
  3. Email 
  4. SMS, phone call 
  • Be aware that it's possible to phish a TOTP code, although this is a lot harder than phishing a password. 
  • "Pay attention!" is good advice all the time.

(You can't control this)
(What can happen to you)
(You control this = What you can do)
Theft of your device: computer tablet, phone, etc. Theft of all data on device Full device encryption (full disk encryption): Strong password or PIN Set auto-erase after ~10 incorrect guesses
Phishing to website with similar name to real one; attack vector is often email Theft of credentials and other personal data via fake website Pay attention! Always fill your credential on a webpage using your password manager (instead of typing them in): it will refuse to fill your credentials into invalid domains
MFA: if you (foolishly) paste your credentials into the site, an attacker still won't have your second factor (e.g., TOTP code).
Phishing to website with internationalized domain name (IDN) homographic name (see IDN homograph attack); attack vector is often email Theft of credentials and other personal data via fake website As just above, plus:
Chrome browser: built in, no action required + Pay attention!
Firefox browser: about:config: set network.IDN_show_punycode to True + Pay attention!
Password guessing on weak passwords Theft of all data in the cloud service Long, random passwords (which are infeasible to guess)
Theft of credentials from Internet service provider (SP), e.g., via break-in to SP's networkCase 1: SP stores the credentials properly (hashed and salted, etc.): Attacker breaks (the easy-to-break) hashed passwords, then uses them on that site and others (because people reuse passwords between sites) Long, random passwords (which are infeasible to break)
MFA -- although attacker might have MFA data too (e.g., TOTP seed)
Case 2: SP doesn't store the credentials properly: Attacker retrieves passwords, then uses them on that site and other sites (because people reuse passwords between sites) Unique passwords
MFA -- although attacker might have MFA data too (e.g., TOTP seed)
Theft of personal data directly from Internet SP providing cloud storage, backup, etc., e.g., via break-in to SP's networkTheft of all data in the cloud service Use zero knowledge services (instead of non-zero knowledge services)
Long, random passwords (which create strong encryption keys)
Various threats above (phishing, password guessing, Theft of credentials from Internet SP, etc.) Takeover of your email account -- then takeover of all accounts that use that email account as the owner/recovery email address Use an email provider that pays attention to security
Use a different (second) email address as the ownership/recovery email address for all your important accounts, instead of using your regular email address
Long, random, unique passwords
Various threats from browsersMalware in ads, various risks from open networks (e.g., open Wi-Fi), etc.Use security type browser extensions such as HTTPS Everywhere, uBlock Origin, and Privacy Badger.

Saturday, May 12, 2018

Core security advice for general users [aka security hygiene]

I finally wrote this up for some family and friends.  I've often tried to convey this information verbally to people when they ask (or when I'm trying to educate), but it's clearly way too much to absorb that way.  Now I can just point them to this blog post.

Here is the list of the core things to do to make your (digital) life more secure and resilient.

Use a secure web-based email service for your primary email account. You want a secure email provider to use for the email address that owns (and is used for password recovery) for all your other accounts.  Gmail is an excellent choice, assuming you don't philosophically want to avoid Google.
You may want to use a different (second) email address as the ownership/recovery email address for all your important accounts, instead of using your regular email address.  Doing so makes it harder for an attacker to find out your ownership/recovery email address, which means it's harder for them to take over that email address and then use it take over your all your accounts using that address.

The passwords for all your accounts -- except for a select few like LastPass -- should be long (e.g. 25+ character), random, and unique, and stored in a good password manager like LastPass.  This includes your passwords for Authy, Gmail,, etc.  Use LastPass's Generate Secure Password feature to generate those long, random, and unique passwords, and store them in LastPass.
(Other good password manager choices include 1Password and Dashlane.  LastPass is the most widely used, so it gets the most attention from security researchers. In any event, use a stand-alone password manager, not one built into your browser.)
Start with your important accounts and, over time, change all the passwords on accounts to long, random, and unique.  "Unique" means that you never use the same password on more than one account: every account gets its own, unique password.  This will protect your from a big class of attacks.

Install LastPass on all your devices so that you can log into your accounts and access other personal information no matter where you are.  This is very handy for when you're not at home or traveling, or for when one of your devices has a problem.

Many services, when you create an account, want you to provide security answers such as your date of birth, your first pet, favorite teacher in grade one, etc.  These are used for account recovery in case you forget your password.  Do not answer those security questions truthfully; instead, treat them like passwords, so create a random string (of letters and digits, say 20 digits) and store that in LastPass.

Set up Multi-Factor Authentication (MFA) -- aka Two-factor Authentication (2FA) -- for all your important accounts that support it, especially LastPass, Gmail, and  It's very important to have MFA on Gmail because if an attacker gets control of it, they can take over most of your accounts. And MFA on LastPass is a very good idea too.  (But if you do that, you need to choose an Authy Backups & Sync password you can and will remember, for recovery purposes.)

Use Authy for MFA; it's more convenient that Google Authenticator.  Install the Authy client on your phone, tablet, and computer, and set up Backups & Sync password so that all your accounts sync across all your devices.  That way you can do the Authy second-factor authentication on any of your devices, which is useful if you forgot or lose one.  Store the Authy Backups & Sync password in LastPass.
When you're configuring an account for MFA, it will offer you "Google Authenticator", if it supports that.  Choose that option, as Authy is completely compatible with Google Authenticator.  Do not install Google Authenticator; instead use Authy wherever you see Google Authenticator mentioned.

Some accounts let you choose to use SMS (aka text messages) for MFA.  SMS for MFA is not so good a choice, because it's possible for attackers to redirect SMS messages to themselves.  If an account gives you a choice, always choose Authy (Google Authenticator) first.  If there is no choice, SMS is better than not having MFA.

You'll want to encrypt your computer's main drive using what's called full drive encryption (or full disk encryption).  That way, if your computer is lost or stolen, no one will be able to pop out the drive and read everything on it.  (Your computer password provides no protection against that, but does protect against other threats, so it should be a quality password.)  With the main drive encrypted you can safely store whatever you want on your drive; more below.

On a Windows machine, the full drive encryption is called BitLocker.  Getting the full BitLocker protection requires that your computer have a Trusted Processor Module (TPM) chip.  Your computer either does or does not have it; if it doesn't, you can't add it.  (The next time you buy a new computer, makes sure it has a TPM.)
In order to get BitLocker itself you'll need Windows 10 Pro instead of Windows 10 Home.  You can buy the upgrade from Microsoft online for about $100 and then download the key.
As you're configuring BitLocker you'll discover that there are two main modes you can choose from: TPM-and-PIN and TPM-only.  (BitLocker also allows an alphanumeric password instead of a numeric PIN.)  TPM-and-PIN is definitely more secure but TPM-only might be secure enough for you -- you'll have to do some reading to decide -- and it's simpler to use.  (If you choose TPM-and-PIN you'll need to type in your PIN, before the Windows password, every time you power on the computer after shutdown or hibernation. You'll get used to this quickly.)  If you choose TPM-and-PIN, disable sleep mode and use hibernation instead.  (By the way, you have the option of using a real password, instead of a numeric PIN, to unlock BitLocker.)
When you set up BitLocker, in either mode, it will generate a recovery key (a string of digits) for you.  You'll likely need to type in this key a couple of times a year, when something goes wrong with BitLocker.  You must store that recovery key somewhere you can get to no matter where you are, so put it in LastPass.

On Macs, macOS come with FileVault 2, which is full drive encryption similar to BitLocker.  Definitely turn it on.
On a Windows machine, to make it more secure, you should make these changes in the BIOS settings:

  • set a BIOS access password (to keep an attacker who gets your machine from changing your settings)
  • enable UEFI mode
  • enable Secure Boot mode

BIOS is a layer of software below the operating system and is often forgotten about.  UEFI and Secure Boot are newer things that your computer either does or does not have; if it doesn't have them, you can't add them.

Encrypt your phone and tablet using the device encryption built into iOS and Android.  This will require setting a PIN or password for the device, which you'd obviously want to do anyway.  Don't use a PIN shorter than six digits, and longer is better.  Do set up automatic wipe on ten incorrect passwords.  You won't lose any data if that wipe happens because you shouldn't be storing any data only on the device: your data master copy should be in a cloud service or on your computer.
If you have a healthy mistrust of computing, you'll see that LastPass is a single point of failure: if you can't access it for any reason, you can't get into any of your accounts.  So remove that SPOF by creating some text document on your computer where you store all your account credentials and other personal information. This file lives on your computer as a backup to LastPass, and store that file in LastPass as well, as an attachment in a Secure Note.

But if you don't encrypt your computer's main drive, then you must not store anything sensitive directly on it, including that file with all your personal information. Without full drive encryption you'll only be able to store sensitive things in LastPass, or in an encrypted virtual drive like VeraCrypt, or on your (encrypted) phone or tablet.  Don't think twice, just encrypt your computer's drive.

You need to have a backup for all the files on your computer.  In fact, you need two backups:

  • one locally, e.g., on a USB external hard drive: encrypt it with BitLocker (called BitLocker To Go when applied to external drives), or macOS Disk Utility, so that it too is secure from loss or theft. (You can store a full main drive backup here too.)
  • one in the cloud: use a zero knowledge service like CrashPlan for Small Business or

"Zero knowledge" (a colloquial, as opposed to technically accurate, term) is a key concept for cloud services.  With a zero knowledge service, your data is encrypted on your device before it leaves the device for the cloud, and the encryption key used is never sent to the cloud.  As a result, if your (encrypted) files in the cloud are stolen, they will be unreadable by the attacker.  This is a good thing. (free for 5 GB) is a service to store data in the cloud and sync between your devices, but it can be used for lightweight backup too.  CrashPlan for Small Business is a real backup service, but at USD $120 per year.  (CrashPlan used to have a Home version, but it was shut down in 2018.) 
Whichever you choose, you should back up all your files both locally (on the encrypted external hard drive) and in the cloud.  If you use CrashPlan for Small Business for backup, you'll likely still want to use to sync key files across your devices, and to share sensitive files with other people.

Web-based advertising is a privacy concern as well as a source of malware, so it makes sense to block as much of it as you can, until the web advertising industry cleans up its act.  The easiest way to do this is to install security- and privacy-type browser extensions such as HTTPS Everywhere, Privacy Badger, and uBlock Origin.
If you do all the above, and don't fall for phishing links, you'll be more secure than 99.9% of people.


Resources if you want to learn more: