Containing a Multi‑Site Phobos Ransomware Outbreak at a Regional Design Firm (August–September 2024)
At a glance
- Customer: IR‑1 subscriber — regional design and professional services firm (APAC)
- Environment: Windows server estate (AD, file servers), backup server / NAS, virtualised workloads, multi‑site network, endpoint security agents
- Attack type: Multi‑site ransomware outbreak (Phobos) with RDP activity, lateral movement, and security control disruption
- Initial vector (assessed): RDP brute force attempts followed by privileged account abuse and lateral movement (patient zero could not be confirmed due to evidence gaps)
- Blackpanda services: IR‑1 rapid response, ransomware scoping, endpoint and log analysis, containment guidance, recovery and security recommendations
CHALLENGE
A “multi‑site” ransomware problem, not a single‑server outage
What began as a file server access issue quickly became a multi‑office operational disruption. Multiple sites reported servers becoming unusable, turning a technical incident into a business continuity event.
Critical servers and core security tooling were in scope
The impact was not limited to low‑value assets. Phobos ransomware activity was identified across critical infrastructure, including AD, file servers, backup storage, and a server containing sensitive HR data. Endpoint protection visibility was further degraded when EDR agents were disabled and the endpoint management server was encrypted.
Investigation constraints increased uncertainty at the worst time
The client needed fast answers on how the attacker got in and whether sensitive data was accessed or exfiltrated. However, several factors constrained certainty:
- Firewall logs had already rolled over by the time full analysis was performed.
- NAT obscured original external source IPs.
- Encrypted virtual machines and hosts limited access to key evidence.
- OS logging gaps limited recovery of certain artefacts (for example, task contents).
- Only a subset of machine images were available for deep review.
In practical terms, leadership needed to act decisively despite incomplete data — which is common in real‑world ransomware events.
SOLUTION
1. IR‑1 activation and rapid triage by Blackpanda incident responders
The customer activated Blackpanda through its IR‑1 subscription once ransomware was identified. Blackpanda confirmed the incident through triage and began containment and investigative work to stabilise the environment and scope impact.
2. Establishing the likely intrusion pattern and spread mechanics
Based on available evidence, initial compromise indicators aligned with credential and remote access attack patterns, including brute force activity and suspicious RDP connections, followed by lateral movement using high‑privilege accounts.
Where possible, Blackpanda helped the client translate these technical findings into operational decisions: what to shut down, what to reset, and what to prioritise for recovery.
3. Confirming ransomware behaviour and persistence tactics
Blackpanda confirmed Phobos ransomware characteristics consistent with:
- Encryption and renaming activity (including a unique extension).
- Deletion of volume shadow copies, reducing recovery options without backups.
- Terminating services and applications prior to encryption to increase success rates.
- Persistence via a Windows Run key autorun entry for the ransomware executable.
4. Balancing data‑access risk with evidence limitations
The incident showed signals consistent with potential data access activity, including suspicious network share access and BITS transfer activity. However, available evidence was insufficient to conclusively determine whether data exfiltration occurred. Blackpanda positioned this clearly: what could be proven, what was suspected, and what could not be confirmed.
5. Containment actions and a practical hardening roadmap
Blackpanda supported the client with immediate containment actions and post‑incident hardening guidance.
Implemented containment measures included:
- Resetting domain administrator accounts to secure privileged access.
- Shutting down affected machines to contain spread and limit damage.
Recommendations focused on preventing recurrence and reducing blast radius, including:
- Implementing centralised logging via a SIEM.
- Disabling unnecessary SMB and RDP services where not required.
- Deploying more tamper‑resistant endpoint detection.
- Applying a defense‑in‑depth strategy.
- Enabling MFA broadly.
- Strengthening backup strategy, including offline or segmented backups and regular restore testing.
RESULTS
1. Confirmed ransomware scope and the assets that mattered most
The client received a clear, evidence‑based view of what was impacted, including the scope across multiple sites and the critical systems involved, rather than relying on assumptions during a high‑pressure period.
2. Stabilised the environment with immediate containment steps
By focusing on privileged access resets and shutting down affected machines, the client reduced the likelihood of continued spread while recovery efforts progressed.
3. Improved security posture with a concrete, prioritised roadmap
The engagement delivered actionable improvements across people, process, and technology: logging retention, service hardening, segmentation, MFA, and resilient backups. These changes are designed to shorten dwell time, limit lateral movement, and improve recovery options in future incidents.
4. Demonstrated value of IR‑1 — cost‑efficiency snapshot
This incident also highlights the economic value of subscription‑based incident response.
Assumptions for an illustrative comparison:
- Client holds a 500‑endpoint IR‑1 subscription
- 70 hours of incident response effort
Indicative cost comparison:
- IR‑1 annual coverage: 500 endpoints × USD 15 per endpoint per year = USD 7,500
- Comparable ad‑hoc IR engagement: 70 hours × USD 500 per hour = USD 35,000
Under this simple comparison, a single 70‑hour incident could cost roughly USD 35,000 on a traditional hourly basis, versus USD 7,500 for a year of IR‑1 coverage — an illustrative saving of ~USD 27,500 (about ~79% less spend) before considering additional readiness and faster mobilisation benefits.
All pricing figures above are indicative examples only and are subject to change at any time.
FAQ: Phobos Ransomware and IR‑1 Response
Q1. How does Phobos ransomware commonly get initial access?
Phobos is commonly associated with remote access exposures and weak credentials, including attacks against RDP. In this incident, evidence included brute force attempts and suspicious RDP connections, although patient zero could not be conclusively identified due to log limitations.
Q2. Why would attackers target backup infrastructure during ransomware?
Ransomware operators often try to impair recovery by encrypting or disabling backup systems and deleting shadow copies. In this incident, both backup infrastructure and volume shadow copy deletion behaviours were observed, increasing reliance on offline or segmented backups for recovery.
Q3. What does it mean when EDR is disabled during an attack?
It reduces detection and response visibility at the time you most need it. Here, EDR agents were disabled on affected machines and the endpoint management server was encrypted, complicating response efforts until protections could be restored.
Q4. Was data stolen in this incident?
The report notes suspected data access signals, but evidence constraints (including log rollover, NAT, and unavailable encrypted systems) prevented confirming data exfiltration volume or method.
Q5. What does IR‑1 change when an incident hits?
It gives you a pre‑established route to activate experienced incident responders quickly, align on a clear process, and prioritise stabilisation, scoping, and recovery decisions without starting procurement in the middle of an incident. Learn more about Blackpanda IR‑1.
What this means for you
Ransomware doesn’t need to hit “everything” to create a full‑scale business disruption — especially in multi‑site environments where identity, remote access, and privileged credentials connect systems together.
If you suspect ransomware activity, report it immediately. If you want predictable, subscription‑based access to human incident responders before the next incident, explore Blackpanda IR‑1 or reach out via Contact.
