TL;DR for Leadership

• What happened: A Chinese state-aligned group compromised a managed service provider (MSP) and used legitimate remote-management tools to pivot into client networks.
• Why it matters: Your strongest control can be bypassed if the vendor you trust is the attacker’s foothold—leading to IP theft, long-term espionage, ransomware staging, and regulatory exposure.
• Act now (7-day plan): lock down third-party identities, ring-fence RMM access, enable per-tenant E5/MDE advanced hunting, rotate all vendor creds, and deploy device-based conditional access.

How the Intrusion Unfolds

1. Initial access at the MSP via phishing, vulnerable VPN, outdated RMM, or stolen OAuth app secrets.
2. Abuse of trust: attackers inherit cross-customer admin rights (global admin, delegated admin, break-glass accounts) or on-prem domain access via site-to-site tunnels.
3. Living-off-the-land: signed RMM agents, PowerShell remoting, WMI, and PsExec blend into normal helpdesk activity.
4. Cloud persistence: malicious Azure AD/Entra apps, mailbox rules, OAuth consents, service principals with excessive Graph permissions.
5. Defense evasion: signed drivers for EDR tamper, log pruning, and exfil over trusted CDN or vendor IP ranges.
6. Objectives: steal source code, designs, supplier pricing, and credentials for later disruptive ops.

High-Signal Detections to Turn On

• Third-party sign-ins: alert when delegated admin (DAP/GDAP) or external tenants log in outside your vendor allowlist, new ASN/geo, or outside change window.
• RMM anomalies: mass process execution, service installs, or agent enrollments from vendor IPs after hours.
• Cloud indicators: new OAuth app with Mail.Read, offline_access, Directory.ReadWrite.All; suspicious consent grants; mailbox auto-forward creation.
• Directory drift: break-glass/global admin usage, privileged group changes, new federation trust, M365 Unified Audit Log gaps.
• EDR tamper: service stop attempts, driver loads not on baseline, exclusion changes pushed via RMM/Intune.

Controls to Implement (Priority → Impact)

• Ring-fence vendor access: move to Granular Delegated Admin Privileges (GDAP) with least privilege; time-boxed, JIT-approved; require MFA + device compliance + IP allowlists.
• Device-bound auth: Conditional Access requires compliant/Hybrid-joined device for any admin action; block service principals from bypassing CA.
• RMM zero-trust: vendor RMM allowed only from jump hosts; per-customer tenants; separate agent certificates; block lateral RDP.
• Secrets & keys: rotate MSP-held passwords, API keys, OAuth secrets, and deployment keys; store in a vault with approvals.
• Network segmentation: place vendor tunnels in a separate zone; use per-customer VLANs; restrict SMB/WinRM to managed subnets only.
• Logging & retention: enable M365 Unified Audit Log, AAD sign-in logs, Defender for Cloud Apps, and retain 180–365 days.
• EDR hardening: block tamper, require signed drivers, remove legacy AV exclusions inherited from MSP templates.

7-Day Action Plan

Days 0–2

• Inventory every external tenant with DAP/GDAP, every OAuth app, and all RMM agents.
• Disable unused delegated admin relationships; move active ones to JIT with approval workflow.
• Block vendor sign-ins that are not from allow-listed ASNs and compliant devices.

Days 3–5

• Rotate all vendor credentials and application secrets; revoke refresh tokens; re-issue per-customer agent certs.
• Implement device-based Conditional Access for all admin roles; require phishing-resistant MFA for vendors.

Days 6–7

• Tabletop: simulate “MSP RMM abused to deploy silent exfil agent.” Validate IR contacts with the MSP, legal/regulatory comms, and customer notification paths.
• Deploy continuous hunting queries (see below) and SOAR isolation steps for vendor-initiated tamper.

Hunting Queries (adapt/translate to your SIEM)

-- Entra sign-ins by external tenants into privileged roles (M365 Defender Advanced Hunting)
IdentityLogonEvents
| where ActionType == "LogonSuccess"
| where AccountDomain != TenantId and isnotempty(Role) and PrivilegedRole == true
| summarize count() by AccountUpn, AppId, IPAddress, Location, tostring(Role), bin(Timestamp, 1h)

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