Account Takeover: What Is It and How to Fight It?

Account takeover is a type of malicious cyber activity in which an unauthorized party gains partial or full control over a legitimate user’s account. And unlike brute-force hacking, ATO focuses on deception, using a combination of stolen information and systemic vulnerabilities to slip under the radar.

It’s tempting to think of account takeover fraud as a niche cybersecurity problem, but the reality is somewhat different. There are multiple ways in which ATO can harm your organization, and they are all incredibly damaging:

• Attackers rarely stop at one account
  ATO is rarely an isolated incident. When attackers compromise any given account, they often use the information within to access other systems. This way, a hijacked email account can reveal information sensitive enough to derail entire corporate networks.

• The monetization factor
  Stolen accounts can also easily act as commodities, often sold in bulk on the dark web to other criminals. Once it happens, it becomes hard to predict what misuse they will find—fraudsters might siphon money directly or use the account to launder funds, or even exploit its legitimacy to carry out scams against others.

• A weapon in broader schemes
  Aside from money laundering, ATO has been used in ransomware attacks, corporate espionage, and disinformation campaigns. A compromised executive’s account, for example, might be used to orchestrate phishing attacks against their own employees or leak sensitive intellectual property.

• Trust erosion
  While financial loss is often the focus, you shouldn’t forget about reputational damage. Each failure at account takeover prevention chips away at trust in your corporate systems—something that any business or institution spends years building.

It’s no big shock that some accounts and industries are more prone to account takeover fraud than others. Attackers carefully choose those ones where the payoff is highest and defenses are weakest—and here are some of them:

Unsurprisingly, the financial account takeover is one of the most common, as it provides the most direct path to stealing massive funds. Bad actors can lunge at virtually anything: internal banking systems, trading platforms, fintech apps, etc. 

Pay special attention to:

• Cryptocurrency exchanges: These platforms often see higher ATO rates because of their irreversible transactions and a lack of standardized regulations.

• Buy now, pay later services: Attackers exploit these relatively new services, knowing that their account takeover detection systems are still maturing.

The retail sector is also a high priority for account takeover attacks because of the sheer volume of customer accounts tied to stored payment methods. Hackers exploit these accounts to place fraudulent orders, steal loyalty points, or resell stolen gift cards.

Pay special attention to:

• Seasonal spikes: A surge in attacks during holidays or major sales events is a common occurrence—increased traffic makes account takeover fraud harder to detect.

• Omnichannel systems: Integrating multiple systems into one creates more room for exploitation if you don’t apply proper security measures.

Medical records can also contain information that has a high price on the dark web—common examples include social security numbers or insurance details.

Pay special attention to:

• Patient portals: Attackers target these to steal identities or commit medical fraud.

• Ransomware attacks: Compromised accounts are often used as an entry point for deploying ransomware, with devastating effects on patient care.

Technology firms, especially software-as-a-service (SaaS) providers are at risk because attackers can—even prefer to—access multiple customer accounts through a single breach.

Pay special attention to:

• Weak API security: Since SaaS platforms integrate with other services, the APIs they use can become an attractive target.

• Administrator accounts: High-level accounts often control access for an entire organization, making the impact of a breach catastrophic.

Universities and schools, with their vast databases of student, faculty, and research information, are often overlooked in ATO discussions. However, attackers have recognized their vulnerabilities, exploiting them for:

• Accessing research data or intellectual property.

• Identity theft using student or staff information.

• Financial fraud through compromised tuition or payroll systems.

• Impersonation of another student during important exams.

While the specifics vary, vulnerable accounts and industries often share the following characteristics:

• High value per account: The higher the value, the greater the appeal. Remember that value isn’t limited to pure funds (like in bank account takeover)—it could also be operational or strategic. Common examples of the latter are admin or enterprise accounts.

• Volume of accounts: Access to millions of user accounts at once is very tempting for ATO attackers.

• Weak authentication: Systems relying on passwords alone or outdated methods (e.g., SMS 2FA) present an easy hacking opportunity.

• Complex ecosystems: Many interconnected systems (e.g., supply chains and third-party integrations) often struggle to secure every access point.

Now let’s take a look at what exactly you need to be prepared for.

Every account takeover attack relies on two essential components: information acquisition and access exploitation.

There are multiple ways in which sensitive information can be obtained by attackers online: data breaches, social engineering, data scraping, and malware, among others.

Data breaches

Data breaches have exposed billions of usernames, passwords, and personal details in recent years, creating a thriving underground market. Attackers often purchase bulk data dumps, searching for high-value targets or just using them for automated attacks like credential stuffing (discussed later).

However, many overlook the more subtle dangers of data breaches:

• Cross-referencing: Attackers can correlate leaked data from multiple breaches to piece together a comprehensive profile of a single individual. For instance, this might be matching a name from one breach with financial information from another.

• Password pattern analysis: People often reuse passwords with only slight variations. Attackers can analyze leaked credentials to predict how users might tweak their passwords.

Social engineering

Breaches aside, attackers often trick users into willingly giving up their details. Some of the most common modern techniques include:

• Voice phishing (vishing): Fraudsters call victims, pretending to be from trusted institutions and convincing them to reveal sensitive data.

• SMiShing: Here, text messages mimic official communications (e.g., delivery notifications or bank alerts) and tell users to click malicious links or provide personal details.

• Pretexting: This involves carefully constructed scenarios designed to manipulate trust—attackers might pose as IT staff requesting a password reset to resolve a “system issue.”

Data scraping

Attackers can also gather info with the help of open-source intelligence (OSINT). It helps bad actors combine your social media profiles and public records to create a detailed profile of you. In turn, such insights can make phishing attempts much more convincing.

Malware

Different types of malware can be used for stealthy information gathering. Keyloggers can record everything a user types, while spyware can monitor all user activity, capturing login credentials as they are entered. Credential-stealing malware like Emotet and TrickBot can even operate on a large scale, infiltrating systems and siphoning data without detection for weeks or months.

Once attackers have the necessary information, they move to the exploitation phase. This is where they weaponize stolen credentials or trick systems into granting them access.

Let’s dive deep into a number of the most common methods.

Credential stuffing

Attackers use automated tools to test thousands or even millions of username-password combinations until they get it right. And since many people reuse their passwords, even old or partial data can massively help bad actors in their credential stuffing activities.

Password spraying

If credential stuffing focuses on specific username-password pairs, password spraying targets the opposite: attackers use a single password (e.g., password123) for multiple accounts. Attackers here try to take advantage of predictable human behavior and find great success in environments with weak account takeover prevention policies.

Session hijacking

Session hijacking means intercepting an active session token—a digital credential that keeps a user logged into a platform. This can be achieved through:

• Man-in-the-middle attacks: Intercepting communication between a user and the server.

• Session token theft: Malware or browser vulnerabilities used to extract session cookies.

SIM swapping

Attackers can impersonate their victim and convince mobile operators to transfer their number to a new SIM card. Once they take control, they can then intercept two-factor authentication (2FA) codes and gain access to accounts that rely purely on SMS-based verification.

So, how to prevent account takeover? Well, now that we know what to expect from malicious attackers, it’s time for the measures you need to take to make your environments ATO-proof.

There’s a whole range of MFA solutions that provide additional account takeover protection on top of passwords. 

Naturally, there is SMS-based verification, which uses SMS to deliver a one-time authentication code, but, as we just discussed, it can be vulnerable to SIM swapping. As a possible upgrade, you can use time-based one-time passwords (TOTP) through apps like Authy or hardware tokens that provide stronger security than SMS. 

Alternatively, you can install systems that assess different contextual factors (location, device type, behavioral patterns) and adjust. This way, a login attempt from a new device might trigger a more rigorous check.

While having a strong password is a must, this is not the only account takeover protection practice you can apply to this security element. 

You should encourage frequent password changes that consistently create new, completely unique passwords. If your users start showing predictable patterns, even regular changes can do very little.

On top of that, you can adopt password managers that will help users generate random, strong passwords without any additional effort on their side. 

And make sure to implement account lockouts after several failed login attempts.

The lingering threat of ATO means that you should continually authenticate and monitor even internal users and devices—but there’s still much to do.

For instance, you can microsegment your networks so that even if one segment is breached, the attacker cannot access your entire system. You should also aim to limit access permissions to a “least privilege” model, which means users can only access what’s absolutely necessary for their role.

Additionally, there is zero trust to mobile approach that demands all mobile devices should be scrutinized more than any others. Anytime someone requests access to a system from a mobile app, such requests should be checked inside and out. 

Also make sure to put automated systems in place that will temporarily suspend any account if it is suspected of being compromised—until the user can verify their identity.

To complete the set of your account takeover protection measures, you should include biometric matching. This technology will allow you to confirm someone’s identity by matching their face to the images collected by you beforehand. 

With the help of a precise biometric comparison engine, you won’t need to fully rely on static data like passwords or authentication codes. And software like Regula Face SDK can provide you with such an engine. The system is also trained to handle variations in image quality and lighting conditions, so that only a genuine live feed is accepted as such, with barely any false negatives.

What’s more, if attackers try to exploit stolen images, videos, or even 3D-printed masks, they will fail yet again. Regula’s liveness detection ensures that the user is physically present during the authentication process. It can examine subtle cues, like light reflection on the skin or natural micro-movements, to confirm the presence of a live human.