Blog & Research

What is Credential Stuffing? And How to Prevent It

Written by Rivanorth | 26 May 2025

Credential stuffing has become one of the most common and effective forms of cyber attack. With billions of leaked credentials available on the dark web, attackers no longer need advanced hacking tools to gain access to your systems. Understanding how credential stuffing works is critical to protecting sensitive data and maintaining customer trust.

What Is Credential Stuffing?

Credential stuffing is a type of cyber attack where criminals use stolen username and password combinations (usually obtained from a previous data breach) and automatically try them across multiple websites or services. And since many people reuse passwords across different platforms, attackers are often successful in gaining unauthorised access.

These attacks are typically automated using bots, which can test thousands of login combinations in a short time. Once an account is compromised, attackers can:

  • Steal personal or financial data

  • Access internal systems and intellectual property

  • Commit fraud or impersonation

  • Launch further attacks within your organisation

The Role of the Dark Web

The dark web plays a central role in the credential stuffing ecosystem. After a data breach, stolen login credentials are often leaked or sold on dark web forums and marketplaces. Attackers use these lists and with the help of automated tools, they test them on services like banking portals, SaaS platforms, ecommerce sites, and corporate systems.

These lists include information like:

  • Emails and associated passwords

  • Password hashes

  • Credential dumps from previous breaches

This means a breach that happened on a third-party platform, such as a SaaS provider or a partner, could still lead to a compromise of your systems if users share the same login credentials.

Signs of a Credential Stuffing Attack

Credential stuffing attacks can often go undetected because they don’t “hack” the system, they simply exploit valid credentials. However, some warning signs include:

  • A sudden increase in failed login attempts

  • A spike in login traffic from unusual locations or IP ranges

  • Accounts being locked out at scale

  • Reports of unauthorised activity from users or customers

Unlike brute-force attacks that guess passwords randomly, credential stuffing relies on known credentials, making it harder to detect with traditional security tools.

Preventing Credential Stuffing

  1. Multi-Factor Authentication (MFA)
    Requiring a second form of authentication significantly reduces the success rate of credential stuffing, even if attackers have valid credentials.
  2. Dark Web Monitoring
    Monitoring the dark web for exposed credentials linked to your organisation is a powerful early warning system. This allows security teams to reset passwords and notify affected users before attackers exploit them.
  3. Password Hygiene and Education
    Avoid password reuse across systems, use strong unique passwords and enable password managers to generate and store secure credentials.
  4. Rate Limiting and Bot Detection
    Implement rate limiting on login attempts and use behavioural analytics or newer versions of CAPTCHA to prevent bot-driven attacks.

Early Detection with Rivanorth Oko

Credential stuffing attacks typically rely on credentials that are already circulating on the dark web, often without the affected organisation’s knowledge. That’s where Oko, Rivanorth’s AI-powered threat intelligence solution, plays a critical role.

Oko scans underground forums, marketplaces, and breach databases for exposed credentials linked to your:

  • Corporate domains and email addresses

  • Employee usernames

  • Customer accounts

By receiving real-time alerts when your data appears on the dark web, you can take immediate action by resetting passwords, locking accounts, and preventing unauthorised access before attackers strike.

Stop Credential Stuffing Before It Starts

Credential stuffing isn’t a complex hack, it’s a consequence of reused credentials, available data, and a lack of visibility. For Australian businesses, the cost of inaction includes financial loss, reputational damage, and compliance issues.

Implementing dark web protection, improving password policies, and proactively monitoring leaked data gives you the upper hand. With tools like Rivanorth Oko, you can spot the warning signs early and shut attackers down before any real damage is done.