Perimeter security assumed that being inside the network implied legitimacy. That assumption held when applications and users were both in the building. It does not survive cloud applications, remote work and third-party access.
What replaces it is not a product. It is making identity authoritative and then actually integrating it.
One directory, genuinely connected
Most estates have an identity platform. Fewer have one that every significant application authenticates against. The gap between those two states is where orphaned accounts, inconsistent password policy and slow leaver processes live.
Integration is the work here — not procurement.
Privilege is the highest-value target
Shared administrative credentials remain common, and they defeat attribution entirely: an audit can establish that something was changed, but not by whom. Brokering privileged access, recording sessions and making elevation time-bound changes that, and it is usually achievable without touching the applications themselves.
Segmentation still matters
Identity does not replace network controls; it complements them. Strong authentication limits who gets in, and segmentation limits where a compromised session can go. Environments that invest in one and neglect the other tend to discover the imbalance during an incident.
In short
Make identity authoritative, integrate it everywhere, control privilege — and keep segmenting.