Malicious UNC4841 Dropper Deployment to Boot Partition via mknod (via process_creation)

ATT&CK techniques

Persistence → Priv Esc

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1546Event Triggered Execution
Priv Esc
- T1546Event Triggered Execution
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects the mknod utility being used to create files within the /boot/os_tools/ directory on Linux-based appliances. UNC4841 staged dropper components in this boot-partition path to survive appliance updates and reboots on compromised Barracuda ESG devices. Writing executable content into the boot partition is highly abnormal and indicates deliberate low-level persistence.

Reporting behind it

Related detections9 linkedT1546 — drag to rearrange

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Malicious UNC4841 Dropper Deployment to Boot Partition via mknod (via process_creation)

Pivot detection · T1546 · 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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