The Passkey Paradox: Endpoint Compromise and Enterprise Risk

The Passkey Paradox: Security Innovation Meets Endpoint Reality

Passkeys have rapidly emerged as a cornerstone of modern identity and access management (IAM), promising a future free from passwords and the persistent threat of phishing. Enterprises are increasingly adopting them to enhance security, streamline user experience, and bolster their overall CIAM strategies. The cryptographic strength of passkeys, rooted in the FIDO2 standard, indeed offers robust protection against traditional credential theft and phishing attacks. However, a flurry of recent research demonstrates a critical nuance: this robust cryptography can be undermined when the underlying endpoint is compromised. For enterprise security architects and IAM engineers, this redefines the threat model and mandates a deeper understanding of the expanded attack surface.

Beyond Phishing: The New Attack Vectors

The core promise of passkeys is their phishing resistance. Unlike passwords, passkeys are cryptographically bound to a specific origin (website or application) and cannot be phished by fraudulent sites. This fundamental design dramatically reduces the efficacy of widespread phishing campaigns. Yet, recent studies have unveiled that while the cryptographic primitives remain sound, the surrounding infrastructure and implementation can introduce new vulnerabilities. These attacks pivot from credential theft to session hijacking and exploitation of compromised devices.

Three independent research teams, along with a fourth documented case, recently demonstrated methods to bypass passkey protections, not by breaking the cryptography, but by targeting the endpoint or the surrounding system [9]. These include:

• Windows Event Log Exposure: Researchers uncovered instances where Windows was logging complete passkey assertions to the event log. In specific configurations, particularly with Microsoft Entra ID, a replay of these assertions could grant access for a limited time (up to 10 minutes). This means that unprivileged malware or even a user with Remote Desktop privileges on a shared server could potentially harvest and replay these assertions, effectively bypassing the passkey authentication without ever touching the user's physical authenticator [8].
• Google's Sync Layer Exploitation: Another vector involved the compromise of Google's passkey synchronization mechanisms. If a synced passkey assertion could be forged or manipulated on a compromised endpoint, it could potentially grant unauthorized access to linked accounts. This highlights the risk inherent in convenience features that abstract away the physical binding of a passkey to a single device.
• Windows Hello Key Store Manipulation: Attacks were demonstrated that leveraged a signed-in user's Windows Hello key to authenticate to Entra ID. This vector suggests that if an attacker has already compromised the endpoint and gained access to the Windows Hello key store, they can effectively impersonate the user even without direct access to the passkey itself. This underscores that the security of passkeys is inextricably linked to the security of the host operating system and its secure element implementations.
• Cached YubiKey Assertions: A fourth documented case revealed that Windows had cached YubiKey assertions in cleartext, allowing any authenticated user to read them. While this specific vulnerability was addressed by July updates, it illustrates the potential for unexpected caching behaviors and data leakage within operating system components [10].

These findings collectively emphasize a critical shift: while passkeys excel at defending against external, network-based phishing, they introduce or exacerbate risks associated with a compromised endpoint. The "Pass-ta-Key" attacks, as some have termed them, demonstrate that the weak point is not the cryptography itself, but the broader ecosystem in which passkeys operate [9].

The Human Element and Social Engineering Reloaded

Beyond technical endpoint compromises, the human element continues to be a significant vulnerability. Cornell University research highlighted how passkeys, despite their technical advantages, can be weaponized in contexts of intimate partner abuse [6]. The paradox of device binding — a strength against external threats — becomes a weakness when devices are shared or when an abuser has physical access. If a shared device has passkeys registered, or if one individual can compel another to authenticate, the "phishing resistance" is effectively bypassed through coercion or shared access. This forces enterprises to consider a broader, social dimension to their security models, moving beyond purely technical controls to address human vulnerabilities and shared device scenarios [7].

Furthermore, "vishing" attacks, which involve voice phishing, have proven effective in exploiting passkey enrollment processes. Attackers leverage social engineering to trick users into enrolling a new passkey under their control, or to approve an authentication request initiated by the attacker. This shows that even with advanced cryptographic methods, the initial enrollment and recovery processes remain critical attack surfaces that are susceptible to sophisticated social engineering techniques.

Enterprise Action: Adapting to the Evolving Threat Landscape

For enterprises deeply invested in passkey adoption, these revelations are not a reason to abandon the technology, but rather to refine implementation strategies and enhance complementary security controls. The shift demands a holistic approach to identity and access management that integrates strong endpoint security with robust passkey governance.

1. Enhance Endpoint Security and Hygiene

Given that many recent passkey attacks originate from a compromised endpoint, bolstering endpoint security is paramount. This includes:

• Advanced Endpoint Detection and Response (EDR): Deploying and actively monitoring EDR solutions to detect and respond to suspicious activity on user devices.
• Least Privilege: Enforcing strict least-privilege principles for all user accounts, including those with administrative rights, to limit the impact of a compromise.
• Regular Patching and Configuration Hardening: Ensuring operating systems and applications are consistently patched and securely configured to minimize known vulnerabilities that attackers might exploit to gain initial access.
• Application Whitelisting: Implementing controls that only allow approved applications to run, thereby reducing the risk of malicious software executing on endpoints.

2. Implement Strong Device Trust and Conditional Access

Enterprises must move beyond simple passkey authentication to evaluate the trustworthiness of the device attempting to authenticate. Conditional Access policies, integrated with Mobile Device Management (MDM) or Unified Endpoint Management (UEM) solutions, can play a critical role:

• Device Health Attestation: Mandate that devices must meet specific security baselines (e.g., up-to-date antivirus, disk encryption, no jailbreaking/rooting) before passkey authentication is permitted.
• Location and Network Context: Utilize geographical location, IP address, and network context as additional signals to assess risk during authentication. Anomalous access attempts should trigger heightened verification or denial.
• Risk-Based Authentication: Implement adaptive authentication that dynamically adjusts security requirements based on real-time risk signals from the user, device, and access patterns.

3. Secure Passkey Provisioning and Recovery Processes

The initial enrollment and account recovery workflows are critical points of vulnerability. Enterprises must review and harden these processes:

• Multi-Factor Verification for Enrollment: Require a strong, out-of-band second factor for enrolling new passkeys, especially for high-privilege accounts.
• Strict Recovery Procedures: Implement multi-step, human-verified account recovery processes that minimize the risk of attackers leveraging social engineering or compromised personal information to regain access.
• User Education: Continuously educate users about vishing tactics and the importance of verifying legitimate requests, particularly when enrolling new authenticators or recovering accounts.

4. Audit and Monitor Passkey Usage and Logs

Proactive monitoring is essential to detect anomalous passkey activity. This involves:

• Centralized Logging: Aggregate authentication logs from all identity providers and applications using passkeys.
• Behavioral Analytics: Utilize User and Entity Behavioral Analytics (UEBA) to identify unusual login patterns, access from new devices, or atypical activity that might indicate a compromised session.
• Alerting: Configure alerts for suspicious passkey-related events, such as multiple failed authentication attempts, passkey registrations from unfamiliar locations, or rapid changes in access patterns.

The Path Forward: Resilient Identity Architectures

Passkeys represent a significant leap forward in authentication security, effectively addressing many long-standing phishing challenges. However, their integration into enterprise environments must be approached with a clear understanding of the broader attack surface. The recent findings underscore that while the cryptography of passkeys is robust, the security of the identity ecosystem is only as strong as its weakest link – often the endpoint or the human element. By combining passkeys with advanced endpoint security, robust device trust, secure provisioning, and vigilant monitoring, enterprises can build truly resilient identity architectures capable of withstanding the evolving threat landscape.