What is an account takeover?
An account takeover (ATO) is a type of cyberattack in which a malicious actor gains unauthorized access to a legitimate user’s account. Instead of exploiting software vulnerabilities, attackers target user credentials to gain access to systems the target user has access to. Malicious actors will often use valid usernames and passwords that have been stolen, leaked or reused across multiple services. Because this type of attack uses legitimate logins, and therefore looks just like a legitimate user, account takeovers can be very difficult to detect without the right security controls in place.
How do account takeovers happen?
Most account takeovers rely on automation and scale in order to be successful. Attackers commonly use credential stuffing, a technique where previously compromised username and password combinations are tested across many websites using bots.
Phishing campaigns, malware, and social engineering also play a major role by tricking users into revealing their login information. In some cases, attackers exploit weak passwords or login endpoints that lack rate limiting or monitoring measures.
The most common ATO methods are:
Credential stuffing which uses leaked username/password combinations
Phishing attacks that trick users into sharing login details
Malware or keylogging that captures credentials
Brute-force attacks against weak passwords
What happens after a successful ATO attack?
After taking control of an account, attackers often act quickly to extract value. They may steal personal or financial data, make unauthorized purchases, change account details, or lock out the legitimate user. Compromised accounts are frequently resold on underground marketplaces or used to launch further fraud, making ATOs especially damaging.
Who do account takeovers target?
Attackers frequently target:
E-commerce and retail accounts
Banking and financial services for their valuable IP
SaaS and enterprise applications
Streaming and subscription services
Gaming and loyalty programs
Any account with stored value, personal data, or reusable credentials is a viable ATO target.
What are the business implications of account takeovers?
Account takeovers directly impact customer trust and brand reputation; Imagine a successful attack on a financial institution that holds your personal data and IP.
Beyond immediate financial losses, organizations face increased support costs, regulatory exposure, and long-term customer churn when they don’t adequately secure against account takeovers. Because ATO attacks often mimic normal user traffic, they can go unnoticed until significant damage has already occurred.
Businesses must have robust security measures in place to ensure they (and their customers) are protected against ATOs
How to prevent account takeover attack?
Preventing account takeovers requires a layered security approach. Strong authentication measures like multi-factor authentication reduce risk, but they are most effective when paired with bot management, behavioral analysis, and real-time traffic monitoring.
Detecting suspicious login patterns and stopping automated abuse at the network edge is critical to preventing attacks before accounts are compromised.
Effective prevention includes a combination of all of the following:
Strong password policies and multi-factor authentication
Behavioral monitoring and anomaly detection
Credential abuse detection at the edge
User education and phishing awareness
How can Fastly help prevent ATOs
Fastly can be a great partner in detecting and preventing account takeover attacks:
Fastly Bot Management automatically identifies and mitigates malicious automated traffic, which is a primary driver of ATOs attacks. It classifies bots at the network edge and uses various server-side and client-side mitigation techniques to prevent resource abuse and fraud, reducing the impact on customer experience and origin costs.
Fastly Next-Gen WAF sits in front of web servers and filters requests for signs of malicious activity. It can detect and block common exploits that might be part of an ATO attempt and helps stop bots before they reach your applications.
Edge Rate Limiting helps control the flow of traffic to prevent abusive bots and mitigate DDoS attacks, which often use techniques like brute-force login attempts.
API and ATO Protection Dashboards: Fastly provides specific dashboards within its Next-Gen WAF to give security teams real-time visibility into API and ATO attacks.
IP Blacklisting: Users have the option to manually ban specific IP addresses known to be associated with problematic traffic patterns, further denying bad actors access.