BP-032: Session Hijack via Token Theft from Sync'd Browsers
A critical identity breach pattern exploiting cloud-synchronized browser tokens to enable cross-device session hijacking and MFA bypass
What This Breach Pattern Is
This breach pattern occurs when attackers steal synchronized browser tokens or cookies from cloud-linked browser profiles including Chrome Sync, Edge Sync, and Firefox Sync. Modern browsers automatically synchronize session cookies, OAuth tokens, refresh tokens, device registration tokens, MFA-related session artifacts, and authentication containers across multiple devices.
When a single device is compromised—whether laptop, tablet, or phone—attackers extract cloud-synced session tokens and replay them from another environment. This results in instant, MFA-less, policy-less impersonation across all connected systems, happening after authentication to bypass traditional security controls.
Bypasses MFA
Token replay occurs post-authentication
Evades Detection
No login events or risk signals
Attack Mechanics
Initial Compromise
Attacker gains access to one synchronized device through malware, phishing, or physical access
Token Extraction
Cloud-synced tokens extracted from browser storage including session cookies and OAuth refresh tokens
Cross-Device Replay
Stolen tokens replayed on attacker-controlled infrastructure bypassing all authentication controls
Hijack sessions across devices and platforms, impersonate users on SaaS and cloud consoles without detection
Privilege Escalation
Escalate privileges through admin portals and bypass SSO restrictions tied to device trust mechanisms
Lateral Movement
Propagate across cloud, SaaS, and internal applications using synchronized authentication tokens
Persistent Access
Maintain persistence via long-lived refresh tokens and gain access to sensitive data with no login events
Synced tokens create a multi-device attack surface that defenders rarely monitor, enabling attackers to operate on new attacker-controlled devices with legitimate user credentials.