New York Attorney General Letitia James today announced the results of a sweeping investigation into “credential stuffing” that discovered more than 1.1 million online accounts compromised in cyberattacks at 17 well-known companies. Attorney General James released a “Business Guide for Credential Stuffing Attacks” that details the attacks — which involve repeated, automated attempts to access online accounts using usernames and passwords stolen from other online services — and how business can protect themselves. Credential stuffing has quickly become one of the top attack vectors online. Virtually every website and app use passwords as a means of authenticating its users. Unfortunately, users tend to reuse the same passwords across multiple online services. This allows cybercriminals to use passwords stolen from one company for other online accounts. Following discovery of the attacks, the Office of the Attorney General (OAG) alerted the relevant companies so that passwords could be reset and consumers could be notified. Today’s guide shares lessons learned over the course of the OAG’s investigation, including concrete guidance on steps businesses can take to better protect against credential stuffing attacks.
“Right now, there are more than 15 billion stolen credentials being circulated across the internet, as users’ personal information stand in jeopardy,” said Attorney General James. “Businesses have the responsibility to take appropriate action to protect their customers’ online accounts and this guide lays out critical safeguards companies can use in the fight against credential stuffing. We must do everything we can to protect consumers’ personal information and their privacy.”
What is Credential Stuffing?
Credential stuffing is a type of cyberattack that involves attempts to log in to online accounts using username and passwords stolen from other, unrelated online services. It relies on the widespread practice of reusing passwords as, chances are, a password used on one website was also used on another.
In a typical credential stuffing attack, an attacker may submit hundreds of thousands, or even millions, of login attempts using automated, credential-stuffing software and lists of stolen credentials downloaded from the dark web or hacking forums. Although only a small percentage of these attempts will succeed, through the sheer volume of login attempts, a single attack can nevertheless yield thousands of compromised accounts.
An attacker that gains access to an account can use it in any number of ways. The attacker can, for example, view personal information associated with the account, including a name, an address, and past purchases, and use this information in a phishing attack. If the account has a stored credit card or gift card, the attacker may be able to make fraudulent purchases. Or the attacker could simply sell the login credentials to another individual on the dark web.
Credential stuffing is one of the most common forms of cyberattack. The operator of one large content delivery network reported that it witnessed more than193 billion such attacks in 2020 alone.
The OAG’s Investigation
In light of the growing threat of credential stuffing, the OAG launched an investigation to identify businesses and consumers impacted by this attack vector. Over a period of several months, the OAG monitored several online communities dedicated to credential stuffing. The OAG found thousands of posts that contained customer login credentials that attackers had tested in a credential stuffing attack and confirmed could be used to access customer accounts at websites or on apps. From these posts, the OAG compiled credentials to compromised accounts at 17 well-known online retailers, restaurant chains, and food delivery services. In all, the OAG collected credentials for more than 1.1 million customer accounts, all of which appeared to have been compromised in credential stuffing attacks.
The OAG alerted each of the 17 companies to the compromised accounts and urged the companies to investigate and take immediate steps to protect impacted customers. Every company did so. The companies’ investigations revealed that most of the attacks had not previously been detected.
The OAG also worked with the companies to determine how attackers had circumvented existing safeguards and provided recommendations for strengthening their data security programs to better secure customer accounts in the future. Over the course of the OAG’s investigation, nearly all of the companies implemented, or made plans to implement, additional safeguards.
The OAG’s Recommendations
Credential stuffing attacks have become so prevalent that they are, for most businesses, unavoidable. Every business that maintains online customer accounts should therefore have a data security program that includes effective safeguards for protecting customers from credential stuffing attacks. Safeguards should be implemented in each of four areas:
- Defending against credential stuffing attacks,
- Detecting a credential stuffing breach,
- Preventing fraud and misuse of customer information, and
- Responding to a credential stuffing incident.
Attorney General James’ guide presents specific safeguards that have been found to be effective in each of these areas. Some highlights from the guide include the following:
- Three safeguards were found to be highly effective at defending against credential stuffing attacks when properly implemented: 1) bot detection services, 2) multi-factor authentication, and 3) password-less authentication.
- Because no safeguard is 100 percent effective, it is critical that businesses have an effective way of detecting attacks that have bypassed other defenses and compromised customer accounts. Most credential stuffing attacks can be identified by monitoring customer traffic for signs of attacks (for example, spikes in traffic volume of failed login attempts).
- One of the most effective safeguards for preventing attackers from using customers’ stored payment information is re-authentication at the time of purchase by, for example, requiring customers to re-enter a credit card number or security code. It is critically important that re-authentication be required for every method of payment that a business accepts. The OAG encountered many cases in which attackers were able to exploit gaps in fraud protection by making a purchase using a payment method that did not require re-authentication.
- Businesses should have a written incident response plan that includes processes for responding to credential stuffing attacks. The processes should include investigation (e.g., determining whether and which customer accounts were accessed), remediation (e.g., blocking attackers’ continued access to impacted accounts), and notice (e.g., alerting customers whose account were reasonably likely to have been impacted).