How to recognize and stop account takeover attacks

Account takeover attacks (ATO) happen when cybercriminals successfully compromise user credentials and gain control of accounts. Unlike traditional hacking methods that exploit system vulnerabilities, ATO attacks use stolen or weak credentials to access accounts through normal login processes. Once inside, attackers can exploit the account for various malicious purposes, from financial fraud to using the compromised account to launch further attacks. According to Gorave and Rautmare in their 2026 study published in the International Journal for Research in Applied Science & Engineering Technology, ATO attacks increased by 30% between 2021 and 2023, reflecting the growing threat as digital adoption continues to expand. More recent analysis by Cochran and Coxe in Security Magazine reveals a trend, reporting that, "ATO attacks have increased by 354% since 2023," showing the nature of this cybersecurity challenge.

Common attack methods

• Credential stuffing: Attackers obtain username and password combinations from previous data breaches and use automated tools to test these credentials across multiple platforms. Research by McElroy in Learning from learning: detecting account takeovers by identifying forgetful users reveals that "65% of users reuse the same passwords across multiple systems." When individuals use the same password across different services, a breach at one site can compromise their accounts elsewhere. McElroy further notes that these credential-stuffing attacks can cost U.S. financial institutions as much as $50 million daily.
• Phishing attacks: These social engineering tactics trick users into voluntarily surrendering their credentials through fake websites, deceptive emails, or fraudulent communications that appear legitimate. Research by Gorave and Rautmare confirms that phishing dominates the credential harvesting system, accounting for 82% of all credential theft incidents.
• Brute force attacks involve attempting numerous password combinations until the correct one is discovered.
• Man-in-the-middle attacks intercept communications between users and legitimate services, allowing attackers to get credentials as they're transmitted. Public Wi-Fi networks and unsecured connections are vulnerable to these attacks.

The impact of account takeover

Besides financial losses, organizations face reputational damage, loss of customer trust, regulatory penalties, and potential legal liability. IBM Security's research, cited by Gorave and Rautmare, found that the average cost of a data breach reached $4.37 million in 2022, more recent data from the Paubox 2025 Healthcare Email Security Report reveals that "the true average cost of a data breach in healthcare is $9.8 million," demonstrating how breach costs have more than doubled in recent years. The report also notes that nearly 70% of IT healthcare leaders estimate HIPAA violation costs would exceed $250,000. A single high-profile breach can destroy brands and customer loyalty. Additionally, compromised business accounts can be used as entry points for broader network infiltration.

According to Cochran and Coxe in Security Magazine, the consequences can include fraudulent transactions where cybercriminals make unauthorized purchases or exploit accounts for illegal activities, data theft leading to identity theft through stolen personal information like Social Security numbers and bank details, financial theft through direct money transfers or maxed-out credit cards, and internal phishing where attackers pose as legitimate account owners to spread attacks throughout an organization.

Gorave and Rautmare also found that 74% of breaches involve human error, this shows that technological defenses alone are insufficient without proper user education and awareness. McElroy's research adds to this challenge, noting that attackers increasingly use interactive social engineering techniques to overcome even two-factor authentication by impersonating financial institutions and convincing victims to reveal one-time passwords over the phone.

Cochran and Coxe note that ATOs are dangerous because they can remain undetected for extended periods. Without active identity verification defenses, these attacks appear as legitimate sign-ins, and users might not notice unauthorized activities immediately.

Organizational defense strategies

According to Cochran and Coxe in Security Magazine, organizations should be alert to key indicators of account takeover, including unusual activity such as fraud alerts or unapproved transactions, multiple failed login attempts that may signal brute force or credential-stuffing attacks, logins from unfamiliar devices or locations that should trigger immediate review, and sudden changes to account settings like email addresses or passwords that can indicate a takeover in progress.

Advanced prevention strategies include implementing account tracking systems that can sandbox suspicious accounts for investigation, deploying AI-based detection systems that analyze behavior patterns and flag anomalies, utilizing web application firewalls to filter HTTP traffic and block malicious requests, and conducting regular security audits including penetration testing and vulnerability assessments. The Paubox report notes the need for proper email security configuration, noting that Microsoft 365 accounted for 43.3% of all healthcare email breaches in 2024, despite many organizations investing in premium E5 security licenses.

Organizations should also maintain incident response plans specifically addressing account takeover scenarios, enabling rapid detection, containment, and remediation of compromised accounts. The research by Gorave and Rautmare shows the need of AI-driven detection systems, which use machine learning models to identify anomalous login attempts and improve detection accuracy, offering promise for future cybersecurity resilience such as Paubox’s inbound email security.

The Paubox report concludes with a warning about the escalating threat landscape, noting that ransomware attacks on healthcare organizations have surged by 264% since 2018. Rick Kuwahara, Paubox Chief Compliance Officer, emphasizes that "the data shows that even the most established email security tools are just a starting point in protecting patient data. To stay compliant, organizations must continuously evaluate their implementations. That can mean adding in additional layers of defense."

FAQs

What is the difference between an account takeover attack and a traditional data breach?

A data breach involves unauthorized access to steal stored data from systems, while ATO attacks use legitimate credentials to access accounts through normal login channels.

How can organizations tell if their account has been taken over?

Warning signs include unexpected password reset emails, unfamiliar devices shown in account activity logs, unrecognized transactions, or being suddenly locked out of your account.

Do multi-factor authentication methods have different levels of security against ATO attacks?

Yes, hardware tokens and authenticator apps are more secure than SMS-based codes, which can be intercepted through SIM swapping or social engineering.

Are certain types of accounts more valuable targets for attackers than others?

Yes, email accounts are valuable because they often control password resets for other services, while financial and administrative accounts offer direct monetary gain.