Security Advisory – Flat Networks Remain Vulnerable Without Tiered Segmentation (SensePost)
What Happened – SensePost published a detailed advisory explaining why flat, unsegmented corporate networks are a critical weakness, even when traditional security tools are deployed. The article outlines how attackers can move laterally across flat networks, harvest credentials from LSASS, and compromise privileged accounts.
Why It Matters for TPRM –
- Third‑party vendors often inherit the same flat‑network design, exposing shared services to the same lateral‑movement risks.
- Lack of segmentation can amplify the impact of a breach in a supplier’s environment, propagating to your organization.
- The guidance provides concrete, repeatable controls (network tiering, zero‑trust zones) that can be incorporated into vendor risk assessments.
Who Is Affected – Enterprises across all sectors that rely on third‑party services hosted on flat internal networks (e.g., SaaS providers, MSPs, cloud‑hosted workloads).
Recommended Actions –
- Require vendors to demonstrate network segmentation (e.g., VLANs, micro‑segmentation, zero‑trust zones).
- Include tiered‑network design checks in your security questionnaire and audit program.
- Validate that privileged‑access services (RDP, SSH, WinRM, LDAP) are isolated from untrusted segments.
Technical Notes – The advisory highlights credential dumping from the LSASS process (clear‑text passwords, NT hashes, Kerberos tickets) and the ease of lateral movement when administrative services are exposed on a flat network. No specific CVE is cited; the focus is on architectural best practices. Source: SensePost Blog – From flat networks to locked up domains with tiering models