Hacker's Guide to (Not) Having Your Passwords Stolen

Online credential theft has exploded in the past several years.  This month alone, numerous breaches have affected millions of users of high profile websites such as LinkedIn, MySpace, vk.com, and Tumblr. In these cases, criminals are not seeking corporate secrets or nuclear launch codes, but rather usernames and passwords for online accounts of everyday computer users.

Credential theft can come in many different flavors with varying levels of impact, from attacks targeting a single or small set of users, to attacks compromising credentials from within an enterprise, to attacks compromising the credentials of millions of users of an online service. While criminals certainly steal usernames and passwords for corporate accounts for extortion and corporate espionage, this article focuses on the compromise of personal  accounts in both targeted mass data breaches. This includes why criminals steal usernames and passwords, and the most common tactics criminals use to steal usernames and passwords. It concludes with some basic steps you can take to reduce your risk of being targeted, as well as how to respond once you’ve been notified of a password breach.

Why do criminals steal usernames and passwords?

The short answer is: for profit, eventually.

The long answer is: it depends.

Hackers steal usernames and passwords from websites for a handful of reasons, but most of them lead to cash eventually. Sometimes criminals steal a database of hundreds of thousands of users from a website and sell it wholesale directly on black market web forums. The larger the database, the more money they can charge for it. Sometimes criminals will use the usernames and passwords to log in to people’s email accounts and send spam email for dubious scam products, making money from referrals and product link-clicks. In each of the cases, the methods of monetization are “quantifiably linear”. The amount of money the criminal makes is strictly tied to the amount of usernames and passwords they steal. The value of the individual accounts is not a consideration.

The next reason criminals steal credentials is as a means to gain access to another, more valuable asset. Usernames and passwords by themselves provide very little value, but the assets that those credentials protect is oftentimes far more valuable. For example, ten thousand valid Gmail usernames and passwords may be worth several hundred or even thousands of dollars on underground criminal forums, but the ability to reset social media and banking passwords, access cell phone provider accounts, read confidential employer information, and even reset other email accounts provides far more value to an attacker.

Criminals steal credentials ultimately to make money or gain access to a more valuable piece of information. It is this monetization of credentials, and the subsequent growth of underground markets, that drives criminals to steal usernames and passwords.

How do hackers steal usernames and passwords?

There are two major categories of how attackers steal usernames and passwords: attacking the users directly and attacking the websites people use.

Attacking Users Directly

These techniques are effective in stealing usernames and passwords from relatively small numbers of people. If an attacker values the account information of a particular targeted person, these techniques also apply.  Some of these methods are obvious to a knowledgeable user and thus easier to protect against. However, as determination and intrusiveness escalates, these methods can be more difficult to stop.  While credentials for many victims of this type of attack can be packaged into large numbers for sale or use, this type of activity does not usually make the headlines.

Some criminals use a technique called  “phishing.” This process usually looks something like this:

1. Hacker finds a large amount of Bank of Somewhere customers
2. Hacker sends a fake login page to legitimate Bank of Somewhere customers hosted on a domain that looks simiar to "bankofsomewhere.com"
3. Some small percentage of the victims unwittingly enter their usernames and passwords into the website that the hacker controls
4. Hacker logs in to stolen accounts, transfer funds to an account they control

Some criminals use even broader phishing attacks to steal social media accounts: 

1. Hacker sends fake Facebook login pages to as many email accounts as possible stating that there is a problem with their account that needs to be fixed
2. Some victims enter their Facebook usernames and passwords
3. Hacker uses access to their Facebook accounts to promote spam and adware-laden websites
4. Hacker generates ad revenue from fake clicks and page visits

Sometimes criminals will want the credentials of a known high-value individual.  More care goes into customization and believability for these cases.  The attacker may go as far as attempting to impersonate the individual in tech support calls, hack the actual computer used by the high-value target to collect credentials, or other invasive techniques.  It can become difficult to defend against a determined attack, but fortunately, most of us aren’t of this level of interest to attackers and basic online hygiene principles listed below will provide some protection.  

Attacking a Website Directly

If a criminal wants to steal millions of usernames and passwords and doesn’t care who gets scooped up, he targets a website directly. The more credentials they steal, the more money they can get selling them or monetizing them in some other way. This almost always comes in the form of a criminal exploiting a vulnerability in the website itself. The criminal uses one of any number of tactics to gain access to the server supporting the website and steals the credentials directly from the database.  The credentials are usually stored as a large set of username and “hashed” password pairs.  A password “hash” simply refers to a more secure method of storing a password where a mathematical representation of your password is stored in lieu of the plaintext password.

Once the criminal steals the database, they often have to recover the passwords from the “hashed” form back to the actual plaintext password, allowing them to check it for likely reuse on other websites. This is accomplished by “brute forcing” the password hashes to recover anything that is computationally guessable (meaning, a password simple enough to be guessed by a wordlist or sequence of iterating characters, like AAAAA, AAAAB, AAAAC, and so on). This last factor is what highlights the importance of strong, complex passwords versus simple, easily-guessable passwords. If your password is a simple dictionary word, for example “baseball”, then your password will almost certainly be very simple to recover from it’s hashed form. Conversely, if your password is long and complex then you are better protected from a large website breach, as it would be computationally infeasible for an attacker to brute force a sufficiently strong password.

An example of this is as follows:

1. Hacker targets a popular social media website called MyBook
2. Hacker finds a vulnerability or misconfiguration in the server hosting the website and uses it to gain access to the website.
3. Hacker locates the database of all registered users and creates a backup
4. Hacker downloads the database backup he created of users and hashed passwords
5. Hacker runs the hashed passwords though a password cracker for a week and recovers 50% of the total passwords
6. Hacker sells the usernames and recovered passwords to someone on an underground hacking forum
7. The person that purchased the database uses an automated program that checks all of the usernames and passwords against other websites for password reuse and gains access to thousands of email, social media, and online banking accounts

How do people protect themselves?

There are a several easy steps you can take to minimize the damage personally inflicted upon you by a password breach.

Use unique passwords on different websites

Imagine having the same key for your house, car, office, and gym locker. While it would be very convenient, it would be a nightmare if you lost it (or worse, if somebody stole it). Criminals gain access to multiple accounts on the Internet because they know that remembering passwords is hard and nobody likes to do it. By having unique passwords on different websites you are reducing the risk of a criminal gaining access to additional accounts as a result of stealing your password.

Use complex passwords

Complex passwords are essential to make them difficult to guess and difficult to recover from a compromised password hash.   I recommend using passwords that are at least 12 characters long that include a mix of letters, numbers, and symbols.  You should avoid using words that would be present in a dictionary to make password guessing and brute-forcing more difficult.  

Use a password manager

Password managers are programs that run on your computer, in your web browser, or directly on your smartphone. Instead of thinking of a password every time you register on a website, the password manager generates a long, complex, random password that you don’t have to remember. Then, whenever you want to log back into that website, you visit your password manager and copy and paste the saved password directly into the website.  LastPass and 1Password are two examples of popular password managers.  It is also important to note that a password manager inherently accomplishes the previous two recommendations.

Use multi-factor authentication on all high value accounts

Multi-factor authentication is a security control that adds an additional layer of security beyond username and password. Multi-factor authentication can come in many different forms, but the most common are a smart phone app, hardware token, or text message codes. Once you’ve enabled multi-factor authentication, you’ll enter your username and password on a website and it will ask you for a third item (a number from an app or a text message).

This ensures that the person attempting to log into the account with your username and password also has your smart phone, and thus, is more likely actually you. Even if a criminal successfully steals your online banking username and password through a targeted email attack or from a third-party website breach, they will not be able to log into your account because they do not have access to your smart phone. The best part is that most major banking, social media, and email providers offer and encourage multi-factor authentication free of charge.

Conclusion

Unfortunately, password breaches and credential theft aren’t going anywhere soon. They are an unwelcome and inconvenient fact of life in the modern Internet era. As long as credential theft remains relatively easy, and the market continues to offer large financial rewards, your usernames and passwords will continue to be highly sought.   The good news is that it’s pretty straightforward to protect yourself from a large majority of the real threats to average computer users. All of the recommended protections are low cost and take no more than an hour to set up. By following these basic steps you can significantly reduce your risk exposure to any credential breach. Now go forth, secure yourself, and use the Internet with confidence.