Third-party Backup Files Deleted via Unexpected Process

Identifies the deletion of backup files, saved using third-party software, by a process outside of the backup suite. Adversaries may delete Backup files to ensure that recovery from a ransomware attack is less likely.

Rule type: eql

Rule indices:

winlogbeat-*
logs-endpoint.events.*
logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://www.advintel.io/post/backup-removal-solutions-from-conti-ransomware-with-love

Tags:

Elastic
Host
Windows
Threat Detection
Impact

Version: 3

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

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## Triage and analysis

### Investigating Third-party Backup Files Deleted via Unexpected Process

Backups are a significant obstacle for any ransomware operation. They allow the victim to resume business by performing
data recovery, making them a valuable target.

Attackers can delete backups from the host and gain access to backup servers to remove centralized backups for the
environment, ensuring that victims have no alternatives to paying the ransom.

This rule identifies file deletions performed by a process that does not belong to the backup suite and aims to delete
Veritas or Veeam backups.

#### Possible investigation steps

- Identify the process (location, name, etc.) and the user that performed this operation.
- Check whether the account is authorized to perform this operation.
- Confirm whether the account owner is aware of the operation.
- Investigate other alerts associated with the user during the past 48 hours.

### False positive analysis

- This rule can be triggered by the manual removal of backup files and by removal using other third-party tools that are
not from the backup suite. Exceptions can be added for specific accounts and executables, preferably tied together.

### Related rules

- Deleting Backup Catalogs with Wbadmin - 581add16-df76-42bb-af8e-c979bfb39a59
- Volume Shadow Copy Deleted or Resized via VssAdmin - b5ea4bfe-a1b2-421f-9d47-22a75a6f2921
- Volume Shadow Copy Deletion via PowerShell - d99a037b-c8e2-47a5-97b9-170d076827c4
- Volume Shadow Copy Deletion via WMIC - dc9c1f74-dac3-48e3-b47f-eb79db358f57

### Response and remediation

- Initiate the incident response process based on the outcome of the triage.
- Reset the password of the involved accounts.
- Perform data recovery locally or restore the backups from replicated copies (Cloud, other servers, etc.).

## Config

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule query

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file where event.type == "deletion" and
  (
  /* Veeam Related Backup Files */
  (file.extension : ("VBK", "VIB", "VBM") and
  not process.executable : ("?:\\Windows\\Veeam\\Backup\\*",
                            "?:\\Program Files\\Veeam\\Backup and Replication\\*",
                            "?:\\Program Files (x86)\\Veeam\\Backup and Replication\\*")) or

  /* Veritas Backup Exec Related Backup File */
  (file.extension : "BKF" and
  not process.executable : ("?:\\Program Files\\Veritas\\Backup Exec\\*",
                            "?:\\Program Files (x86)\\Veritas\\Backup Exec\\*"))
  )

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Impact
- ID: TA0040
- Reference URL: https://attack.mitre.org/tactics/TA0040/
Technique:
- Name: Inhibit System Recovery
- ID: T1490
- Reference URL: https://attack.mitre.org/techniques/T1490/

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