Your vendors often have weaker authentication controls than you do. They may not enforce multi-factor authentication (MFA) consistently. Staff may reuse the same password across multiple systems with no one flagging it. That’s exactly why so many attackers target the vendors in your supply chain instead of targeting you directly.
Password spraying attacks are one of the most common ways threat actors gain a foothold in enterprise environments. They often do it without ever directly touching your network. Understanding how this attack works and why your vendors are the preferred target is one of the most practical steps you can take right now.
What Is Password Spraying?
Password spraying is a type of brute force attack in which an attacker tries a single password against many accounts. Instead of flooding one account with many guesses, the attacker spreads attempts across hundreds or thousands of accounts. This distinction matters enormously for detection. Account lockout policies trigger when one account receives too many failed attempts. Password spraying sidesteps that entirely. Each account sees only a few failed attempts — never enough to trigger a lockout.
In a typical spray, an attacker runs through a list of usernames. They try the same small set of common passwords against each one. These are passwords like “Welcome1,” “Summer2024,” or the organization’s known default credential. The result is a method that can run for hours or days with almost no visible footprint.
Password Spraying vs. Brute Force
Password spraying is technically a brute force attack, but the mechanics are different enough that most brute force defenses won’t catch it. Brute force floods a single account. Password spraying is slow, patient, and deliberately calibrated to evade detection.
Password Spraying vs. Dictionary Attacks
A dictionary attack tests a long list of passwords against one account. Password spraying flips this: one password, or a very small set, tested across as many accounts as possible. Both methods exploit weak passwords and poor password hygiene. The difference is operational, and it’s exactly what makes spraying so hard to catch with standard security measures.
Examples of Password Spraying in Practice
Real-world examples show how quickly these attacks scale. An attacker targeting a mid-sized enterprise might compile employee usernames from LinkedIn. They select three commonly used passwords. They test those passwords across every account over 48 hours, staying well below the lockout threshold on any individual login. Admin accounts are particularly valuable targets. A single compromised admin account can give an attacker reach far beyond a standard user.
Our STRIKE team documented a campaign involving over 130,000 compromised devices. The campaign conducted large-scale password-spraying attacks against Microsoft 365 accounts. It exploited non-interactive sign-ins with Basic Authentication to bypass MFA enforcement. This is now a defining indicator of a password spray at enterprise scale.
Why Vendors Are the Preferred Target
Your vendors often have weaker authentication controls than you do. Their Active Directory hygiene may lag behind yours by years. When an admin sets a default password during account provisioning and never changes it, that account becomes an easy target.
This is what makes a compromised vendor account so valuable. An attacker using legitimate-looking credentials can access your systems through trusted integrations, application programming interfaces (APIs), and shared access points. They do this without triggering the alerts an unknown IP address would. The attacker is logging in rather than breaking in. Your vendor attack surface is also larger and harder to monitor. Hundreds of third parties each run their own authentication practices. Understanding how third-party risk compounds this exposure is one of the most important steps you can take before the next spray campaign begins.
How Password Spraying Attacks Unfold
A typical password spray follows a predictable sequence:
- The attacker compiles usernames from public sources such as LinkedIn, breach data, or credential stuffing databases
- They select commonly used passwords or known defaults at the target organization
- They distribute login attempts across accounts at a pace that stays below detection thresholds
- Successful matches give the attacker a compromised account with legitimate credentials
- From there, the attacker may move to privilege escalation, lateral movement, or data exfiltration
What makes this especially dangerous in a vendor context is dwell time. The attacker may sit quietly inside a vendor’s environment for weeks. By the time activity is detected, the breach may already have cascaded into your systems through shared supply-chain access.
The Business Impact of a Successful Spray
A successful password spraying attack is rarely contained to one account. Once an attacker establishes a foothold, the impact spreads. Recovery can take weeks. Customers are less likely to trust that their data is safe after a breach becomes public. A vendor-sourced intrusion that reaches your environment creates breach notification costs, regulatory scrutiny, and reputational damage. Attackers who access financial accounts can initiate unauthorized transfers. Access to customer data opens doors to secondary fraud. In regulated industries, the compliance exposure from a single compromised account can be significant.
What Makes Organizations Vulnerable
The conditions that allow password spraying to succeed are well understood:
- Weak passwords or poor password hygiene across vendor user accounts
- No MFA on vendor-facing portals or shared systems
- Default passwords set during system configuration that vendors never change
- Absent or misconfigured lockout policies that don’t flag login attempts spread across many accounts
- No monitoring for distributed authentication attempts from rotating IP addresses
- Single sign-on misconfigurations that allow one compromised account to access multiple systems
The attack looks like noise. Only correlating attempts across accounts and time reveals the pattern.
How to Prevent Password Spraying Attacks
Preventing password spraying requires layering controls across both detection and access. These measures give your security team the most leverage:
- Enforce MFA across every login surface that touches your environment, including vendor portals, shared platforms, and APIs
- Implement password managers across your organization and require vendors to do the same, eliminating credential reuse
- Set up detection for distributed login attempts that flags authentication attempts spread across accounts from a single IP or rotating IP set
- Review lockout policies so the failure threshold catches spraying patterns without locking out legitimate users
- Establish a clear recovery process so that when lockouts occur, the reset workflow doesn’t create a gap attackers can exploit
- Apply zero trust principles to all vendor access, requiring continuous verification rather than trusting a prior successful login
- Audit default passwords across vendor systems, particularly admin accounts, and require policy-compliant credentials before granting access
Network security monitoring can detect password spraying by linking failed login attempts across multiple accounts during the lockout period. This is more effective than looking at one account at a time. Account-level controls miss the wider pattern. One of the clearest warning signs is a sudden rise in failed login attempts spread across many accounts over a short window.
Requiring Better Authentication From Vendors
Preventing password spraying at the vendor level requires the same rigor you apply internally, enforced contractually. Vendor security assessments should specifically ask about MFA coverage, lockout policies, and how vendors handle account resets after a spraying incident. Spot-checking vendor login infrastructure against known spraying tools is worth including for high-risk suppliers.
The challenge is that most vendor authentication hygiene is assessed at onboarding and rarely revisited. Password policies drift. Staff turnover means default passwords get set and forgotten. A vendor that passed an assessment eighteen months ago may look very different today. The 10 cybersecurity criteria for smarter vendor selection offer a practical framework for building authentication requirements into procurement from the start.
How TITAN AI Surfaces Authentication Risk Across Your Vendor Ecosystem
This is precisely where continuous monitoring changes the outcome. TITAN Watch gives you real-time visibility into your vendor ecosystem. It surfaces signals like exposed login portals, misconfigured authentication endpoints, and security score degradation that often precede password spraying incidents. Rather than solely relying on a vendor’s self-reported questionnaire responses, TITAN Watch gives you an objective, outside-in view of what attackers actually see when they look at your vendors.
For organizations managing large vendor portfolios, TITAN Assess automates the security questionnaire and assessment process at scale. It streamlines how you send, complete, and analyze vendor assessments, including those covering authentication practices. Rather than chasing vendors for evidence every assessment cycle, TITAN Assess turns a weeks-long manual process into one that takes minutes.
Password spraying remains one of the simplest and most effective techniques in a threat actor’s toolkit. You’ll catch it earliest when you have real-time visibility into your vendors’ authentication posture, not just your own.
Ready to see authentication risk across your vendor ecosystem before it becomes an incident? Book a demo with SecurityScorecard.
