Boot-Sector - CraftedSignal Threat Feedhttps://feed.craftedsignal.io/tags/boot-sector/Trending threats, MITRE ATT&CK coverage, and detection metadata. Fed continuously.Hugoenhello@craftedsignal.iohello@craftedsignal.ioTue, 09 Jan 2024 12:00:00 +0000Suspicious Raw Disk Access Detectedhttps://feed.craftedsignal.io/briefs/2024-01-09-raw-disk-access/Tue, 09 Jan 2024 12:00:00 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2024-01-09-raw-disk-access/Detection of processes accessing raw disk volumes outside of normal system paths, often associated with wiper malware and boot sector attacks.This brief focuses on detecting anomalous raw disk access attempts on Windows systems. The activity is flagged via Sysmon EventCode 9, which logs raw disk reads. Threat actors frequently leverage raw disk access for destructive purposes like wiping, encrypting, or overwriting the boot sector, rendering systems inoperable. Notably, malware families like HermeticWiper have employed this technique to devastating effect. This detection excludes legitimate system processes by filtering known good paths like \Windows\System32\ and \Windows\SysWOW64\. The successful execution of such an attack can lead to complete system failure, data loss, and significant operational disruption. Understanding and detecting this activity is crucial for preventing severe damage to targeted systems.

Attack Chain

  1. Initial Access: The attacker gains initial access to the target system through various means (e.g., exploiting vulnerabilities, compromised credentials, or social engineering).
  2. Privilege Escalation: The attacker escalates privileges to gain necessary permissions for raw disk access, often requiring SYSTEM-level access.
  3. Disable Security Controls: Attempts to disable or evade security products that might interfere with disk access (e.g., anti-virus, endpoint detection and response (EDR)).
  4. Raw Disk Access: A malicious process initiates raw disk access using Windows APIs to directly read or write to the disk volume partitions (Sysmon EventCode 9). Example: \\Device\\HarddiskVolume1.
  5. Boot Sector Modification: The attacker overwrites the Master Boot Record (MBR) or other critical boot sectors with malicious code.
  6. Data Wiping/Encryption: The attacker uses raw disk access to wipe partitions by overwriting data with random bytes or encrypting data without providing a recovery key.
  7. System Crash/Reboot: The compromised system crashes or is forced to reboot.
  8. Denial of Service: Upon reboot, the system fails to start due to the corrupted boot sector or wiped partitions, resulting in a denial-of-service condition.

Impact

Successful raw disk access attacks can result in complete data loss, system inoperability, and significant operational disruption. The HermeticWiper attack in 2022 impacted hundreds of systems across multiple organizations, primarily in Ukraine, causing widespread data destruction and hindering critical services. Organizations across all sectors are potentially vulnerable, with financial, government, and critical infrastructure entities being prime targets. The cost of remediation can range from tens of thousands to millions of dollars, depending on the scale of the attack and the complexity of the recovery process.

Recommendation

  • Enable Sysmon Event ID 9 logging to capture raw disk access events. This will activate the core detection mechanism (Sysmon EventID 9).
  • Deploy the provided Sigma rule Raw Disk Access Outside System Paths to detect processes accessing disk volumes from unusual locations. Tune the filters based on your environment.
  • Investigate any alerts generated by the Sigma rule Raw Disk Access by Unusual Processes for processes not commonly associated with disk operations to identify potentially malicious activity.
  • Implement application control policies to restrict which processes can execute and access sensitive resources, mitigating the risk of unauthorized disk access.
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