LinuxAESDDoS

Hunt Hypothesis

The LinuxAESDDoS rule detects potential distributed denial-of-service (DDoS) activity by identifying suspicious patterns of traffic or payload behavior associated with Linux-based systems. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage DDoS attacks that could escalate into larger network disruptions.

YARA Rule

rule LinuxAESDDoS
{
    meta:
	Author = "@benkow_"
	Date = "2014/09/12"
	Description = "Strings inside"
        Reference = "http://www.kernelmode.info/forum/viewtopic.php?f=16&t=3483"

    strings:
        $a = "3AES"
        $b = "Hacker"
        $c = "VERSONEX"

    condition:
        2 of them
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 3 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: System Backup Using dd with AES Encryption
  Description: A system administrator is performing a backup of a disk using the dd command with AES encryption for secure storage.
  Filter/Exclusion: Check for the presence of known backup tools (e.g., tar, rsync, borgbackup) or filter by command-line arguments like if=/dev/sdX and of=/backup/encrypted_disk.img.

• Scenario: Scheduled Disk Imaging for Forensic Purposes
  Description: A scheduled job runs dd to create a forensic image of a disk for legal or compliance reasons.
  Filter/Exclusion: Use a filter for processes initiated by a known forensic tool (e.g., dcfldd) or check for the presence of a scheduled task with a specific name or user (e.g., forensic_team).

• Scenario: Admin Task to Encrypt a Disk Using dd
  Description: An admin is encrypting a disk using dd and AES encryption to secure sensitive data before decommissioning a device.
  Filter/Exclusion: Filter by the user account (e.g., root or admin) and check for the presence of encryption-related commands or tools (e.g., openssl, cryptsetup).

• Scenario: Automated Disk Cloning for Testing Environments
  Description: A CI/CD pipeline or test environment uses dd to clone a disk image for development or testing purposes.
  Filter/Exclusion: Filter by the source and destination paths (e.g., /dev/sdb to /mnt/test_disk) or check for the presence of a test environment label or user (e.g., test_user).

• Scenario: Encrypted Volume Mount Using dd
  Description: A system is mounting an encrypted volume using