Credential Stuffing Attacks Are Surging: What Financial Services Firms Need to Know

Credential stuffing has become one of the fastest-growing threats in the advisory world, and it works without breaking a single system. Credential stuffing used to be background noise. Now it’s one of the top threats targeting the financial services industry.  The reason: attackers don’t have to “hack” anything. They simply log in with real credentials—often stolen from unrelated breaches. For firms holding sensitive financial, retirement, or deal-related data, it’s a perfect storm.

What Is Credential Stuffing?

Credential stuffing is when criminals use stolen usernames and passwords from other breaches and try them across your logins (M365, CRM, deal rooms, TPA portals, custodians).

If an employee reused a password anywhere else — shopping, social media, newsletters — attackers can often use it to access your internal systems.

That’s why this attack is so dangerous:

• It looks like a normal login

• It bypasses firewalls

• It targets cloud apps 

• It hits the people with access to money and data

Why It’s Exploding Right Now

AI automation is the biggest driver. Attackers can now test millions of stolen credentials and rotate their activity to look legitimate.  At the same time, advisory firms are more cloud-based than ever:
M365, Salesforce, Orion, Deal Rooms, Addepar, TPA Portals — all attractive targets if a single password works.

And the data these firms hold? Extremely valuable: retirement elections, investor details, ACH instructions, deal documents, personal financial plans.

No wonder attackers are going up-market.

What a Successful Attack Looks Like

Once a credential works, attackers typically:

1. Log in quietly

2. Browse email and files

3. Imitate an advisor or partner

4. Steal data or initiate fraud

No alarms. No obvious break-in. Just normal-looking access with very abnormal intent.

How Firms Can Shut This Down Quickly

You don’t need 20 steps — just the right few:

1. Use stronger MFA

Prefer passkeys, FIDO keys, or number-matching. (SMS codes aren’t enough anymore.)

2. Disable legacy authentication

This is still enabled in many M365 environments and is the #1 MFA bypass.

3. Add simple access rules

Block risky sign-ins, require MFA for anything sensitive, and watch for impossible travel.

4. Train employees on MFA fatigue

One accidental “Approve” can equal a breach.

5. Monitor for compromised credentials

If an advisor’s password is leaked, you need to know fast. These steps close the biggest gaps immediately.

The Bottom Line

Credential stuffing isn’t a technical exploit — it’s identity theft applied at scale. For RIA firms, investment teams, and TPAs, it’s already one of the most common ways attackers get in. Strengthen identity and you eliminate the vast majority of the risk.

Sixwatch Can Help

Sixwatch specializes in securing environments for financial services firms with identity-first protection that stops credential attacks before they start. If you want a fast identity-security check for your firm, Schedule your complimentary Assessment.