Post-merger integration is the process of combining systems, data, and workflows after an acquisition. In cyber security, it matters because the merger creates a temporary high-risk state: identity stores may be duplicated, old accounts may still work, and data may move between platforms that were never designed to trust each other. ERP, HR, CRM, and cloud services often need new connectors, permissions, and audit controls.
Attackers can exploit rushed integrations through misconfigured access, orphaned credentials, exposed data shares, or overbroad permissions that reveal customer or financial records. Defenders reduce this risk by inventorying assets, mapping data flows, enforcing least privilege, validating business workflows, and retiring legacy access as soon as possible. Good post-merger integration is not just an IT cleanup task; it is a security control that determines whether combined operations become more resilient or more exposed.