Single Sign-On (SSO) is widely adopted for its ability to streamline authentication, reduce password fatigue, and improve user experience. But beneath the surface, SSO also introduces serious security trade-offs - especially in the context of ransomware, privilege escalation, and supply chain attacks. By consolidating access into a single authentication gateway, SSO creates a high-value target: compromise one credential, and an attacker could unlock access to an entire network of applications.
In this blog, we’ll explore the main vulnerabilities of SSO and why it continues to be a central focus for attackers - from MFA fatigue and token hijacking to privilege misuse and SSO provider compromise. We'll then outline the most effective strategies to mitigate these risks, including how to enforce least privilege, strengthen authentication, manage sessions securely, and ensure provider resilience.
If you're relying on SSO, it's crucial to understand both the attack surface it creates and the layered defences required to secure it.
🔑 1. Single Point of Failure
- Lateral Movement: Once attackers compromise an SSO account, they gain immediate access to all connected systems and applications—meaning an entire breach can unfold from a single credential compromise.
- SSO Provider Supply Chain Risk: Attacks on SSO providers (e.g., interception of Okta or Azure identity systems) can cascade, affecting numerous organisations relying on those platforms.
🚨 2. Privileged Escalation
- Admin Accounts Cause Greater Damage: If a privileged SSO user is compromised (Administrator, IT staff), attackers can rapidly elevate privileges, modify configurations, and deploy ransomware across the network.
- Shared Credentials Exposure: Poorly managed privileged accounts—especially those with broad roles—make ransomware attacks easier, underscoring the need for Privileged Access Management (PAM).
🛡 3. Bypassing Least-Privilege Principles
- When SSO is not tightly scoped, users gain wide-ranging access by default. This breaks the principle of least privilege, allowing attackers to roam freely once inside
🌀 4. MFA Fatigue & Push Notification Attacks
- MFA Fatigue Attacks: Attackers flood users with authentication requests, hoping they “click yes” out of annoyance or confusion. Once accepted, they gain full access. These MFA bypass techniques have been used effectively in Lapsus$ attacks on Uber and others.
🕵️♂️ 5. Token Hijacking & Session Exploits
- Existing Active Sessions: Even if credentials are reset post-attack, active SSO sessions remain valid. Attackers can stay logged in to services unless sessions are forcibly revoked.
- Token & Assertion Theft (SAML/OAuth): SAML or OpenID Connect tokens may be vulnerable to signature wrapping or replay attacks, allowing session hijacking even with MFA in use .
🔐 🧱 Strategies to Protect Against (or Mitigate) Attacks on SSO
While Single Sign-On (SSO) simplifies authentication and improves user experience, it also creates a high-value target for attackers - compromising one account could unlock access to an entire suite of systems.
To reduce the risks associated with this “all-or-nothing” model, organisations must adopt a layered defence strategy that reinforces identity security at every stage. Below are key strategies to protect against or mitigate attacks on SSO:
- Privileged Access Management (PAM): Vault and rotate privileged credentials, enforce step-up authentication, limit time-bound access.
- Zero Trust & Least-Privilege: Break SSO into micro-segments—avoid “master key” model and enforce identity-based access policies.
- Phishing and MFA Resistance: Deploy hardware tokens or FIDO2 passkeys, shorten token lifetimes, and monitor MFA push behaviour.
- Session Management: Enable real-time session invalidation post-incident, block old tokens, and require re-authentication.
- Continuous Monitoring: Monitor identity platform events and anomalous access—track token use and alert on unusual patterns.
- Provider Resilience: Choose SSO providers with robust supply-chain security and redundancy; keep an incident recovery plan for IDP outages.
🧠 Summary
SSO’s convenience also becomes its primary risk during a cyberattack - compromise one credential, and the attacker effectively gets the keys to all systems.
To make SSO secure, it needs to be part of a layered identity strategy involving PAM, zero-trust, phishing-resistant authentication, session controls, and active monitoring.
