Suspicious Symlink Evaluation Enabled via fsutil

ATT&CK techniques

Impact

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
- T1490Inhibit System Recovery

What it detects

This rule detects fsutil being used to enable remote-to-local and local-to-remote symbolic link evaluation, a preparatory action BlackCat/ALPHV ransomware performs to reach and encrypt files across mounted and networked paths. Attackers enable this so encryption can follow symlinks to additional data. This uncommon fsutil configuration change is a distinctive BlackCat pre-encryption step.

Reporting behind it

Related detections9 linkedT1490 — drag to rearrange

Malicious Volume Shadow Copy Deletion via wmic and vssadmin (via process_creation)

Malicious System Recovery Inhibition via bcdedit and vssadmin in Mallox

Malicious Shadow Copy Deletion via WMIC via Process Creation (via process_creation)

Suspicious Anti-Recovery Zeroing via fsutil setZeroData (via process_creation)

Malicious Shadow Copy Removal via WMI PowerShell

Malicious Volume Shadow Copy Deletion via vssadmin

Malicious Inhibit System Recovery via Shadow Copy and Boot Config Tampering (via process_creation)

Malicious Recovery Disablement via Bcdedit RecoveryEnabled No

Suspicious Volume Shadow Copy Deletion via vssadmin or wmic

Suspicious Symlink Evaluation Enabled via fsutil

Pivot detection · T1490 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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