Most discussions about cybersecurity revolve around external threats: ransomware gangs, zero-day exploits, supply chain attacks, botnets.

But there is another category of threat, just as dangerous — and often far more unpredictable:

The internal threat.

This case study presents a real incident involving:

• Manipulation of Veeam backup jobs

• Forced encryption on all jobs

• Retention reduced to a single day

• Abuse of the Four-Eyes approval mechanism

• Compromised MFA-protected accounts

• Unauthorized access to the Veeam server

• Destruction of the entire local repository

• Removal of all ESXi VM files

• And even the creation of a fake ransomware note to mislead investigators

Despite the severity, the environment was fully restored in less than 48 hours thanks to:

• A hardened, off-site immutable repository

• Instant Recovery

• Proper datacenter structure

This article aims to show that:

• Internal sabotage is real

• MFA alone does not guarantee integrity

• Immutability is not optional

• Proper backup architecture saves entire companies

• And Veeam can rebuild a destroyed environment rapidly

All details below are presented neutrally, without assigning personal blame — focusing only on the technical lessons.
This is a genuine incident shared to strengthen the community.

The Forensic Timeline: From Departure to Full Destruction

Thursday — The silent trigger

A team member was dismissed in the morning.
No incident, no tension, nothing suspicious.

But beneath the surface, something was already brewing.

Monday — First warning: Backup Copy jobs failing

Routine checks revealed that several Backup Copy jobs to the off-site immutable repository were failing.

[04.09.2025 17:16:14.673] Info (17) Job session 'be9404f-7048-48e6-b9de-e3db989e2c81' has been completed, status: 'Failed'.
[04.09.2025 17:16:14.701] Info (17) [CJobLogsManager] Cannot find quota. Job with id 3a9c1d43-0887-3b5-8652-e99782d20058 was not found.

Upon investigation:

• All jobs were suddenly encrypted

• Each job had a different encryption password

• Retention was reduced to 1 day

• Four-Eyes Authorization logs showed abnormal patterns

[26.01.2026 22:00:14.394] Info (3) [CBackupOptions] Load from DB: OK.
[26.01.2026 22:00:14.394] Info (3) [CBackupOptions] Encryption enabled: True
[26.01.2026 22:00:14.394] Info (3) [CBackupOptions] Encryption algorithm: AES256

The logs revealed:

• The nominal account of the former employee requested changes

• A generic service account approved them instantly

• In some cases, the generic account requested something, and the nominal account approved immediately

[25.01.2026 03:00:12.662] Info (3) [TaskBuilder] Couldn't find per extent info. BackupId: 0d1154cf-e191-4063-9f78-4062dc2083af.
[25.01.2026 03:00:12.662] Info (3) [TaskBuilder] Build tasks for repository c7e3667a-b007-47ce-8876-f80fc837d35c (Rep Cloud - veeam-bkp-anu)

Forensic conclusion:
The same person controlled both accounts — including their MFA tokens.

This was the first sign of internal sabotage, or at least compromised credentials.

The job failure that saved the environment

When encryption was force-enabled on all jobs, Veeam attempted to perform:

• A full backup synchronization to the immutable repository

But there was not enough space for a full backup.
The job failed — and this failure prevented malicious overwrites.

Because of the hardened repository’s immutability, all restore points remained intact.

This single detail is the cornerstone of this entire internal sabotage recovery with Veeam immutable backups case.

[25.01.2026 01:35:13.150] Info (15) [CTransportSvcAgentManager] Checking whether agent 'adbfa34c-14f1-4ea7-9bbf-b08889c74b8a' is alive on host '172.X.X.X'

Monday afternoon — First containment actions

Emergency actions were taken:

• Password resets

• Removal of suspicious accounts

• Only two accounts remained:

  • My administrative account

  • The client’s administrative account

But here lies another major issue:

The client reused the same password across different systems.

The dismissed employee had this password.

Even after rotating most credentials, one password remained compromised.

Tuesday — Escalation: unauthorized access to the Veeam Server

Using the client’s credentials, the attacker did not access the Veeam Console.
Instead:

He accessed the Windows Server hosting Veeam.

Once inside:

• Formatted all disks of the local repository (not immutable)

• Deleted the Veeam configuration database

• Left a fake ransomware note attempting to simulate an external attack

The intention was clear:
Create confusion, redirect blame, and destroy the ability to investigate.

[27.01.2026 16:10:11.088]    <15>   Error (3)    Error:
[27.01.2026 16:10:11.088]    <15>   Error (3)    SQL server is not available, id d1169bc-b40f-46e8-8976-7ec3176b4297, 140 times since 01/27/2026 00:21:10
[27.01.2026 16:10:11.089]    <15>   Error (3)    [ViHostHierarchyManager:192.x.x.x] Veeam.Backup.Common.CSqlException: The SQL Server machine hosting the configuration database is currently unavailable. Possible reasons are a network connectivity issue, server reboot, heavy load or hot backup.
[27.01.2026 16:10:11.089]    <15>   Error (3)    Please try again later.
[27.01.2026 16:10:11.089]    <15>   Error (3)    Error:
[27.01.2026 16:10:11.089]    <15>   Error (3)    SQL server is not available ---> Veeam.Backup.Common.CSqlException: The SQL Server machine hosting the configuration database is currently unavailable. Possible reasons are a network connectivity issue, server reboot, heavy load or hot backup.
[27.01.2026 16:10:11.089]    <15>   Error (3)    Please try again later.

Minutes later — The final blow: deletion of all ESXi VM files

With the same credentials, the attacker accessed ESXi and:

**Deleted every VM file. The entire environment went down instantly.**

What could have been a ransomware-level disaster was, in fact, an internal sabotage event.

The Recovery: How Veeam Immutable Backups Saved the Entire Environment

Despite the total destruction of:

• Local repository

• Veeam database

• All ESXi VM files

…one thing remained untouched:

The off-site hardened repository with immutable backups.

The attacker could not access it.
Could not delete it.
Could not encrypt it.
Could not corrupt it.
Could not overwrite it.

This is exactly the scenario for which immutability exists.

Step 1 — Rebuilding the Veeam Server

A new Veeam Server was deployed.

Step 2 — Importing the immutable backups

The off-site repository was scanned, and all restore points were recognized automatically.

Step 3 — Instant Recovery

Critical systems were brought online immediately:

• Domain Controllers

• DNS

• File servers

• Internal apps

• Databases

Instant Recovery provided operational services while storage was rebuilt.

Step 4 — Migration to production

Over the next hours, each VM was migrated from the Instant Recovery datastore to final storage.

Total time to full production: under 48 hours

While the original environment had been completely destroyed.

This is the true power of:

internal sabotage recovery with Veeam immutable backups

Key Lessons Learned

• Immutability is mandatory

Without it, the company would be lost.

• Credential hygiene is critical

Reused passwords are a ticking time bomb.

• MFA is not invincible

If someone controls both the password and the MFA device, MFA becomes meaningless.

• Internal threats are real

Sometimes more dangerous than ransomware.

• Veeam Instant Recovery is a lifesaver

Downtime was minimized dramatically.

• Hardened repositories truly “hold the line”

Linux immutability with single-use credentials prevented total data loss.

Key Lessons Learned

Immutability is mandatory

As a result, immutability protected the environment even when every other layer failed. Moreover, it prevented tampering with restore points during the attack. In addition, it stopped the malicious encryption and retention changes from spreading. Therefore, immutable storage remains the strongest defense against destructive actions. Ultimately, no modern environment should operate without it.!-->

Credential hygiene must improve

Because of this, the attacker moved freely between systems using reused passwords. Furthermore, weak credential practices accelerated the compromise. As a result, several layers of the environment became exposed. In addition, enforcing unique credentials and rotation policies avoids cascading failures. Therefore, strong credential hygiene directly reduces internal and external risks.

MFA is not invincible

However, MFA fails when one person controls both the password and the MFA device. Consequently, the attacker bypassed the approval workflow. Moreover, this showed how MFA alone cannot guarantee proper isolation. For this reason, MFA must be combined with secure device management and strict identity separation. Ultimately, MFA remains effective only when each identity belongs to a different human with a different device.

Internal threats deserve equal attention

Meanwhile, many companies still focus only on external attackers. Even so, internal access can cause faster and more precise damage. For this reason, monitoring and auditing must cover every privileged account. Additionally, role separation avoids concentrated power in a single identity. Consequently, treating insider threats with the same importance as ransomware greatly increases security. Ultimately, internal risks cannot be ignored.!-->

Instant Recovery drastically reduces downtime

In fact, Instant Recovery brought critical services online while infrastructure was still being rebuilt. Moreover, this capability kept the business operating during the crisis. As a result, the environment returned to production in less than two days. Furthermore, the migration to final storage happened gradually without interrupting operations. Therefore, Instant Recovery significantly minimizes outage duration during severe incidents.!-->

Hardened repositories hold the line

Because of this, the hardened Linux repository resisted every deletion attempt. Furthermore, single-use credentials prevented any remote wipe attempt. Consequently, all restore points stayed intact regardless of the sabotage. In addition, Linux immutability isolated the storage from Windows-level attacks. Therefore, hardened repositories serve as the final guarantee of recovery. Ultimately, they ensure data survival even under complete infrastructure compromise.

Forensic Flow Diagram (ASCII)

[Employee Terminated]
          |
          v
[Backup Jobs Manipulated in Veeam]
          |
[Encryption + Retention Reduction]
          |
[Four-Eyes Approvals Abused]
          |
[Attacker Controls 2 Accounts + MFA]
          |
          v
[Access to Veeam Server (Windows)]
          |
 [Local Repo Formatted] -- [DB Deleted]
          |
          v
 [Fake Ransomware Note Planted]
          |
          v
[Access to ESXi]
          |
          v
[All VM Files Deleted]
          |
          v
  [Full Environment Down]
          |
          v
[Off-Site Immutable Backups Safe]
          |
          v
 [New Veeam Server + Import]
          |
          v
    [Instant Recovery]
          |
          v
[Full Production Restored < 48h]