C3RB3R / .L0CK3D on NAS: Data Extraction and the RFC Assessment Process

1. Match C3RB3R indicators against the actual incident

.L0CK3D contains a zero, rather than the letter O. A note named read-me3.txt provides another identification clue. Neither the extension nor the note's filename establishes the complete incident sequence.

SentinelOne's research describes C3RB3R on Windows/Linux, .L0CK3D files and encryption of accessible SMB shares. This makes workstations, servers and accounts with NAS write access relevant to the investigation. It does not establish that the malware executed inside the NAS operating system. This is an investigative consideration, not a finding about Ticket #1377. [1]

A threat in a ransom note is also insufficient evidence of data theft. Assessing encryption and investigating exfiltration are related tasks that require their own evidence.

2. Distinguish three recovery paths

A raw scan or extension change does not turn encrypted content into a readable document. Removing the extension or trimming a few hundred trailing bytes cannot restore an encrypted payload. Fully encrypted files need a clean source or a valid cryptographic recovery path; destructive overwriting that removes information presents a different problem.

No More Ransom lists a tool for CERBER V1. That scope does not establish support for every Cerber/C3RB3R variant. This article does not confirm a compatible decryptor for Ticket #1377. Use tools from a verified source only after preserving the original data. [2]

3. RFC: Six assessment steps before extraction

Step 1 — Coordinate containment

Work with the IT lead to stop suspicious writes and access, and protect remaining safe backups. Record discovery time, messages and actions already taken. Power and memory-collection decisions depend on the situation; there is no universal power-off rule for every system.

Step 2 — Record RAID, volumes and drives

Inventory drive count/order, RAID configuration, filesystem, legitimate at-rest encryption and any I/O faults. A healthy RAID does not establish that files are intact. Distinguish Ransomware damage from physical drive faults or storage-structure corruption.

Step 3 — Preserve the source and create suitable copies

Where appropriate, create a controlled drive image/clone or volume copy and record handover details and actions. Physically failing sources need a suitable reading strategy that limits repeated reads. Do not experiment with formatting, initialisation, RAID rebuilds, filesystem repair or recovery tools on the original or only copy.

Step 4 — Inventory available recovery sources

Check offline/immutable backups, snapshots, version history, independent replicas, workstations and application copies. Earlier content is recoverable only while the necessary information survives. Deleted snapshots, reused extents, SSD TRIM and garbage collection can remove opportunities; copy-on-write is not a recovery guarantee.

Step 5 — Extract selectively using copies

Prioritise business-critical data and sample multiple formats and sizes. Check file structure, readable regions and completeness rather than relying on filenames. Where partial encryption is suspected, compare legitimately supplied original/encrypted pairs on copies to assess the affected range.

Step 6 — Validate use and document handover

Record extracted files, remaining faults and validation results. The customer accepts the work against agreed criteria. A byte count, percentage of readable bytes or “copy successful” message does not establish usable business data.

4. Extracted files need real validation

• DOCX/XLSX: check container structure, open documents and review the necessary content, worksheets or formulas.
• PDF, images and video: check pages, image content and readable/playable sections rather than filenames alone.
• SQL Server: assess consistency in a suitable environment and validate records using the business application.
• VMs/backups: check dependencies and readability, and test restore/boot in an isolated lab where appropriate.

For an estimated 5 TB NAS, identify accounting, ERP, project records or other priority datasets first. Volume does not make every file equally important. An outcome from another ticket cannot establish a recovery commitment for this system.

5. After the incident: Backups must be recoverable

RAID provides drive-failure tolerance within its design. Snapshots may offer earlier versions while intact. Synchronisation can propagate unwanted changes. Assess these mechanisms within a backup design that includes independent copies, separate administrative access and restore testing.

The 3-2-1-1-0 approach calls for three copies including production, two media types, one off-site copy, one offline/air-gapped or immutable copy, and verification aiming for zero recovery errors. Choose retention, RPO/RTO and capacity for the actual business requirements. [3]

Responders need to contain compromised access before data returns to production. Data extraction is one part of the work; it does not replace the full security incident response.

6. What should you prepare for TUNGTEK?

• Affected system type, discovery time and observed file extension.
• Redacted screenshots and a record of actions already taken.
• Backup/snapshot condition and priority data.
• An authorised contact to agree handover scope and receive results.

Do not send sensitive documents, passwords, private keys or access links in the initial description. Tung TEK helps clarify the condition, RFC scope, proposed approach, costs and validation criteria before work starts. Recovery percentages are not promised without supporting evidence.

Prepare an RFC request · Data handling and intake · Incident response and police reporting guidance.

7. Frequently asked questions

References and article scope

1. SentinelOne — C3RB3R analysis, .L0CK3D, ransom notes and SMB shares. External campaign research, not an attribution of Ticket #1377's entry point.
2. No More Ransom — Tools and supported variants.
3. Veeam Best Practice Guide — The 3-2-1-1-0 approach.

Edited from the owner-supplied TEKLink218 package and reviewed on 29 October 2026. The anonymised case remains under assessment. No private samples, logs, hashes, token-bearing links or unverified outcomes are published. Images are editorial illustrations, not photographs of the customer's system.