Exposed Secrets: Unmasking Data Breaches, Stolen Credentials & Illicit Dark Web Bazaars

Infostealer malware is a significant and often underestimated threat to corporate information security teams. These malicious programs infect computers, steal credentials saved in browsers, along with active session cookies and other data, and send it back to the attacker’s command and control infrastructure. In some cases, the malware even self-terminates after completing its mission.

In this article, we’ll discuss how cybercriminals use stolen credentials to gain unauthorized access to privileged IT infrastructure, leading to data breaches and ransomware attacks. But infostealers aren’t the only threat; leaked credentials from more traditional sources continue to pose substantial risks to organizations.

It’s no secret that people often reuse the same password across multiple applications, creating a perfect opportunity for hackers to brute force their way into software-as-a-service (SaaS) and on-premises applications.

At IT Services, we currently monitor over forty million stealer logs. This number is growing by millions every month, with an expected increase in 2024. Additionally, we monitor over 14 billion leaked credentials found in data dumps across the dark web.

This unique perspective allows us to see firsthand how threat actors acquire, distribute, and use leaked credentials.

Understanding Leaked Credentials

To better comprehend leaked credentials, we can categorize them into tiers based on the method of leakage and the risk they pose to organizations. This approach, pioneered by Jason Haddix, helps security professionals clearly communicate credential leak risks to managers and corporate executives.

Tier 1 Leaked Credentials

Tier 1 leaked credentials result from third-party application or service breaches. When these breaches occur, all users of the affected service have their passwords compromised and distributed in a data dump on the dark web. This is the most common type of leaked credential.

For example, imagine a fictional corporation called Scatterholt with user logins for hundreds of thousands of consumers. If attackers breach Scatterholt and access the identity and access management system, they could steal these credentials and leak them onto the dark web.

Scatterholt could force a password reset for all users, but it’s likely that many users have reused the same password across other services. This leak gives threat actors the opportunity to use brute force techniques to gain access to other applications that share the same password.

Defending Against Tier 1 Leaked Credentials

Organizations can employ several well-researched defenses to reduce risk. First and foremost: monitor a leaked credentials database for corporate employee emails. This single action can make a massive difference as threat actors deliberately target passwords associated with corporate email addresses to facilitate data breaches.

Secondly, require users to routinely reset passwords on a schedule, ensuring that if a specific password is breached, they will have already rotated other corporate credentials.

Finally, we recommend using a password manager with a policy requiring employees to randomize passwords for various applications and store them securely, reducing the risk of employees making only minor changes to passwords.

The Special Case of Combolists

Combolists are collections of credential pairs, organized by service or geographically, used by cybercriminals in combination with brute force tools to attempt to gain access to various services.

These credentials often come from previous known breaches, stealer logs, or are entirely fabricated. The exact source is never entirely clear, but the sheer volume of credentials available through combolists, combined with frequent password reuse, makes them a significant attack vector.

Tier 2 Leaked Credentials

Tier 2 leaked credentials pose a unique risk to companies. These credentials are harvested directly from users through infostealer malware that steals all passwords saved in the browser.

We consider tier 2 leaked credentials to be of significantly increased risk to both the company and the user for the following reasons:

• A single stealer log will contain all of the credentials the user saved in their browser. This creates a perfect opportunity for threat actors to socially engineer the victim, the IT help desk, or even the company using the victim’s information.
• These logs contain the plain text username, password, and host for the credentials, often for hundreds of different logins. Threat actors have an enormous advantage when they can see dozens of password variations that the user uses.
• These logs often contain form-fill data with answers to secret questions, which can be effectively used to bypass websites with secret questions.

Tier 3 Leaked Credentials

This tier of leaks, also from stealer logs, poses an extreme risk to organizations. Fresh stealer logs often contain active session cookies, which threat actors can easily use for session hijacking attacks. In these attacks, they impersonate the victim and potentially bypass two-factor authentication (2FA) and multi-factor authentication (MFA) controls.

Discovering a fresh stealer log with corporate credentials should immediately prompt an incident investigation, as it’s highly likely that the passwords are working and that threat actors could directly access corporate resources.

Defending Against Tier 3 Leaked Credentials

Limit the time-to-live (TTL) for corporate applications to reduce the risk of session cookies remaining valid if distributed as a result of an infostealer infection.

Multi-Factor Authentication Isn’t a Silver Bullet

Not monitoring leaked credentials likely means that many of your employees use single-factor authentication, as their passwords may have been exposed. Many people believe that enabling 2FA is sufficient protection against stolen credentials, but the reality is that threat actors are aware of the obstacle 2FA presents and have developed techniques to overcome it.

Whether through social engineering of employees, using 2FA bots to capture one-time codes/passwords from victims, or even SIM-swapping, there are many ways to bypass MFA controls that are actively used in the wild.

The best defense against these types of attacks involves using authenticator apps, which feature temporary rotating codes instead of one-time passwords received via email or SMS. These applications are usually more secure and ensure that the user controls a second device to some extent.

Concerned about Credentials? We Can Help

IT Services monitors more than 14 billion leaked credentials distributed on the dark web and hundreds of millions leaked through infostealer malware.

Our platform sets up in 30 minutes and provides robust detection for leaked employee credentials across hundreds of forums, channels, and marketplaces.

Check out our free trial.

Sponsored and written by IT Services.