01 · Starting point
Situation
After the security incident, existing assumptions about the directory service, network, clients, policies and local rights could not simply be reused. Recovery therefore meant not just restoring, but building a target environment whose trustworthiness could be verified.
Constraints
- Compromised starting environment after a ransomware attack
- Very large client estate with differing health states
- Security requirements and operability had to be addressed at the same time
02 · Responsibility
My scope of responsibility
As a freelance Senior System Architect I developed the recovery concept for the network and Active Directory. I analysed the state of 54,000 clients, supported clean-up and migration planning and reduced local administrator rights with PowerShell.
- My scope included analysing the documented state of 54,000 clients.
- I supported the clean-up strategy and planned the migration path for users, policies and resources.
03 · Technical work
Documented scope of work
Key decisions
Build a trustworthy target structure rather than merely repairing the compromised environment. A clearly defined trust boundary creates a more resilient foundation for identities, policies and later migrations.
Systematically assess client health and local rights before migration. Endpoints must not carry risks unnoticed into the new environment; at the same time the migration path has to remain scalable.
- Within the recovery team I developed a concept for the network and a newly built Active Directory structure.
- PowerShell-based procedures were used to reduce local administrator rights.
04 · Technical context
Technology in use
Active Directory
A newly built Active Directory structure was part of the recovery concept.
PowerShell
PowerShell supported the reduction of local administrator rights.
DNS
DNS and network dependencies were taken into account in the recovery concept.
Group Policy
Group policies were part of the planned migration path.
Security
Client state, clean-up strategy and trust boundaries were considered from a security perspective.
05 · Factual basis
Evidence and limits
The deliverables were the recovery concept for the network and Active Directory, the analysis of 54,000 clients, migration planning for users, policies and resources, and the PowerShell-based hardening of local administrator rights.
- Scope analysed
- 54,000 clients
- Recovery focus
- Network, Active Directory, client health and privilege hardening
Lesson from the engagement
After a security incident speed matters — but trust only comes from a clear target architecture, verifiable states and controlled transitions.
Confidentiality note: Security-relevant architecture and incident details remain confidential.