Bootkit
A bootkit is a malware variant that modifies the boot sectors of a hard drive, including the Master Boot Record (MBR) and Volume Boot Record (VBR). (Citation: MTrends 2016) Adversaries may use bootkits to persist on systems at a layer below the operating system, which may make it difficult to perform full remediation unless an organization suspects one was used and can act accordingly. ### Master Boot Record The MBR is the section of disk that is first loaded after completing hardware initialization by the BIOS. It is the location of the boot loader. An adversary who has raw access to the boot drive may overwrite this area, diverting execution during startup from the normal boot loader to adversary code. (Citation: Lau 2011) ### Volume Boot Record The MBR passes control of the boot process to the VBR. Similar to the case of MBR, an adversary who has raw access to the boot drive may overwrite the VBR to divert execution during startup to adversary code.
Mitigations |
|
| Mitigation | Description |
|---|---|
| Bootkit Mitigation |
Ensure proper permissions are in place to help prevent adversary access to privileged accounts necessary to perform this action. Use Trusted Platform Module technology and a secure or trusted boot process to prevent system integrity from being compromised. (Citation: TCG Trusted Platform Module) (Citation: TechNet Secure Boot Process) |
| Privileged Account Management |
Manage the creation, modification, use, and permissions associated to privileged accounts, including SYSTEM and root. |
| Boot Integrity |
Use secure methods to boot a system and verify the integrity of the operating system and loading mechanisms. |
Detection
Perform integrity checking on MBR and VBR. Take snapshots of MBR and VBR and compare against known good samples. Report changes to MBR and VBR as they occur for indicators of suspicious activity and further analysis.
References
- Lau, H. (2011, August 8). Are MBR Infections Back in Fashion? (Infographic). Retrieved November 13, 2014.
- Mandiant. (2016, February). M-Trends 2016. Retrieved January 4, 2017.
- Microsoft. (n.d.). Secure the Windows 10 boot process. Retrieved April 23, 2020.
- Trusted Computing Group. (2008, April 29). Trusted Platform Module (TPM) Summary. Retrieved June 8, 2016.
Связанные риски
Каталоги
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