Response playbooks, investigation guides, and Atomic Red Team tests are Pro-only. Upgrade to unlock the full detection package for THREAT-CloudBackup-SnapshotPurge.
Upgrade to ProDetect Cloud Backup Vault and Snapshot Deletion Prior to Ransomware Detonation in Google Chronicle
As organizations move backup targets from on-premises VSS/wbadmin to cloud-native services (AWS Backup, EBS/RDS snapshots, Azure Recovery Services vaults, Azure managed-disk snapshots), ransomware affiliates have adapted their recovery-inhibition step to match: rather than running vssadmin on an endpoint, the attacker who has obtained cloud administrative credentials calls the backup/snapshot service's own deletion APIs directly. Observed patterns include bulk deletion of AWS Backup recovery points and backup vaults (DeleteRecoveryPoint, DeleteBackupVault, DeleteBackupPlan, DeleteBackupSelection), direct deletion of EC2/RDS snapshots (DeleteSnapshot, DeleteDBSnapshot, DeleteDBClusterSnapshot), and — on Azure — first disabling the Recovery Services vault's soft-delete protection before deleting protected items or the vault itself (soft-delete exists specifically to survive this attack, so its removal is itself a strong signal), plus deletion of standalone managed-disk snapshots. This is functionally identical in intent to T1490's on-host VSS/BCD deletion but lives entirely in cloud control-plane audit logs (AWS CloudTrail, Azure Activity Log) rather than endpoint telemetry, and the key discriminator from legitimate lifecycle-policy cleanup is who/what made the call: automated retention-policy expiration is initiated by the backup service itself (e.g. CloudTrail invokedBy backup.amazonaws.com), while an interactive IAM user or role deleting many recovery points/vaults in a short window is anomalous and, combined with a soft-delete-disable step on Azure, should be treated as an active pre-encryption indicator.
MITRE ATT&CK
- Tactic
- Impact
YARA-L Detection Query
rule cloud_backup_snapshot_purge {
meta:
author = "df00tech Detection Engineering"
description = "Detects burst deletion of cloud backup vaults, recovery points, and snapshots consistent with pre-ransomware recovery denial"
reference = "https://attack.mitre.org/techniques/T1490/"
severity = "CRITICAL"
priority = "HIGH"
mitre_attack_tactic = "Impact"
mitre_attack_technique = "T1490"
false_positives = "Backup lifecycle expiration, planned decommissioning, cost-optimization pruning, vault migration"
version = "1.0"
events:
$e.metadata.event_type = "USER_RESOURCE_DELETION"
(
(
$e.metadata.vendor_name = "Amazon"
re.regex($e.metadata.product_event_type, `(?i)(DeleteRecoveryPoint|DeleteBackupVault|DeleteBackupPlan|DeleteBackupSelection|DeleteSnapshot|DeleteDBSnapshot|DeleteDBClusterSnapshot)`)
not re.regex($e.metadata.description, `(?i)backup\.amazonaws\.com`)
) or
(
$e.metadata.vendor_name = "Microsoft"
re.regex($e.metadata.product_event_type, `(?i)(RECOVERYSERVICES.*BACKUPCONFIG|RECOVERYSERVICES.*PROTECTEDITEMS.*DELETE|RECOVERYSERVICES/VAULTS/DELETE|COMPUTE/SNAPSHOTS/DELETE)`)
)
)
$identity = $e.principal.user.userid
match:
$identity over 30m
condition:
$e
}Chronicle YARA-L 2.0 rule matching USER_RESOURCE_DELETION UDM events from AWS CloudTrail and Azure Activity Log. Fires on AWS Backup/EBS/RDS deletion calls not attributed to the backup service itself, and Azure Recovery Services soft-delete-disable, protected-item/vault deletion, or managed-disk snapshot deletion. Groups by calling principal over a 30-minute window to surface the burst pattern characteristic of a scripted recovery-denial operation.
Data Sources
Required Tables
False Positives & Tuning
- Backup lifecycle/retention expiration not fully attributed to the service identity
- Planned environment decommissioning with bulk deletion
- Cost-optimization snapshot pruning
- Vault migration projects disabling soft-delete temporarily
- Backup/DR testing in non-production environments
Other platforms for THREAT-CloudBackup-SnapshotPurge
Testing Methodology
Validate this detection against 2 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Simulate AWS Backup Recovery Point Deletion Burst
Expected signal: AWS CloudTrail management events: eventName=DeleteRecoveryPoint, eventSource=backup.amazonaws.com, three or more events from the same userIdentity.arn within a few minutes, with userIdentity.type NOT equal to AWSService.
- Test 2Simulate Azure Recovery Services Soft-Delete Disable Then Protected Item Removal
Expected signal: Azure Activity Log entries: operationName=MICROSOFT.RECOVERYSERVICES/VAULTS/BACKUPCONFIG/WRITE (soft-delete disabled) followed within minutes by operationName=MICROSOFT.RECOVERYSERVICES/VAULTS/BACKUPFABRICS/BACKUPPROTECTIONCONTAINERS/PROTECTEDITEMS/DELETE, both with resultType=Success from the same caller.
References (7)
- https://attack.mitre.org/techniques/T1490/
- https://attack.mitre.org/tactics/TA0040/
- https://docs.aws.amazon.com/aws-backup/latest/devguide/API_DeleteRecoveryPoint.html
- https://docs.aws.amazon.com/aws-backup/latest/devguide/API_DeleteBackupVault.html
- https://learn.microsoft.com/en-us/azure/backup/backup-azure-security-feature-cloud
- https://learn.microsoft.com/en-us/azure/backup/backup-azure-delete-vault
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1490/T1490.md
Unlock playbooks & atomic tests with Pro
Get the full detection package for THREAT-CloudBackup-SnapshotPurge — response playbook and atomic red team tests, plus investigation guidance and hunting queries.
df00tech Pro — £29/user/month