How to Detect and Stop Credential Stuffing on Your API

What is Credential Stuffing?

Credential stuffing is a type of brute-force attack where stolen usernames and passwords from data breaches are used to gain unauthorized access. These attacks often target APIs directly, especially login endpoints. According to industry reports, credential stuffing makes up more than 80% of login attempts on some services.

How Credential Stuffing Works

• Attackers use large lists of leaked credentials from the dark web.
• They automate login attempts via scripts or botnets.
• They rotate IPs, use residential proxies, and mimic real devices to bypass basic defenses.

Key Indicators of Credential Stuffing

• High volume of login attempts from the same IP or across multiple IPs in short timeframes.
• Same email logging in from many geographies or devices.
• Sharp spikes in 401/403 status codes from a single IP or network.

How to Mitigate Credential Stuffing

• Rate limit login attempts per IP and per user/email.
• Geo restriction: Only allow logins from expected countries/regions.
• IP reputation checks: Block known VPN/proxy or blacklisted IPs.
• Mobility rules: Detect and restrict account access from multiple new IPs in a short time.
• Behavior-based anomaly detection: Trigger MFA or block when suspicious patterns occur.

How APIGate Helps

With APIGate, you can implement all of the above with:

• Rate limits by email and IP (minute/hour/day windows).
• Geo-based access controls and VPN/proxy detection using a 600M+ IP reputation database.
• Real-time anomaly detection for status codes and access patterns.
• Triggered actions like rate limit, block, MFA flagging, or alerts.

Conclusion

Credential stuffing is a silent, costly threat — but with intelligent monitoring and access control, you can detect and neutralize it early. APIGate provides the tools to protect your API endpoints without degrading performance or adding heavy engineering overhead.