VMDK encrypted by ransomware
1️⃣ Symptoms of a VMDK Encrypted by Ransomware
VMDK files (Virtual Machine Disk) are virtual disks used by VMware and other virtualization solutions. When ransomware targets them:
File extension modification
Example: .vmdk → .vmdk.locked, .vmdk.anubis, .vmdk.crypt
The ransomware renames the file to indicate that it has been encrypted.
Inaccessibility of the virtual machine
The VM no longer boots. VMware or vSphere will display errors such as:
“VMware cannot open the virtual disk”
“Failed to open the virtual disk: the file is corrupted or encrypted”
Visible corruption in snapshots
Associated snapshots may become unusable if the ransomware also encrypts .vmsn or .vmsd files.
Presence of ransom notes
In the same folder, a text or HTML file indicates the ransom amount, the contact address, and payment instructions.
Impacted VM logs.log files may contain error entries related to mounting or reading the disk.
2️⃣ Impact on Data Recovery
Data recovery depends heavily on the extent of the encryption and the availability of backups:
If the ransomware only encrypted the VMDK
It becomes impossible to mount or access the virtual machines directly.
Standard recovery tools (Recuva, R-Studio, Stellar) do not work because the content is cryptographically encrypted.
Only an intact backup or a specialized ransomware-encrypted file recovery solution can restore the data.
If fragments or snapshots are corrupted
The VMDKs may be partially recoverable.
Virtual machines may boot, but some applications or databases may be corrupted.
Impact on time and complexity
The process is long and delicate because it often involves:
analyzing the encryption algorithm used by the ransomware,
identifying unencrypted or partially recoverable VMDK blocks,
reconstructing the virtual disk structure (VMDK descriptor + data).
A full recovery can take several hours to several days for a single 100 GB to 1 TB VMDK depending on the complexity.
Recovery may fail entirely if:
no backup exists,
the VMDK was completely overwritten by a wiper,
the encryption algorithm is strong and specific to that ransomware family.
3️⃣ Estimated Time to Recover a VMDK
| Scenario | VMDK Size | Backup Availability | Complexity | Estimated Time |
| Full offline backup | 200 GB | Yes | Low | 1 to 2 hours (standard restoration) |
| Encrypted VMDK but accessible fragments | 500 GB | Partial | Medium | 8 to 24 hours (analysis + reconstruction) |
| Encrypted VMDK without backup | 1 TB | No | Very high | 3 to 10 days (manual analysis, limited recovery possible) |
| VMDK destroyed by ransomware with wiper | 1 TB | No | Impossible | Recovery impossible |
4️⃣ Critical Points to Remember
- Never attempt to mount an encrypted VMDK: this can cause additional corruption.
- Do not delete the file or attempt formatting: every byte is valuable for recovery.
- Prioritize offline backups: if a snapshot or a Veeam, ESXi, or Hyper-V backup exists and was not accessed by the ransomware, it is the best recovery source.
- Specialized tools: some data recovery companies (such as Recoveo and Digital Recovery) have tools capable of:
- analyzing the encrypted VMDK,
- reconstructing partially intact blocks,
- recovering critical files even without full decryption.
- Actual recovery time depends on the disk size, the type of encryption used, and the condition of the VMDK.