Killmbr

Overview

Trojan:Win32/Killmbr (or KillDisk) is a classification for destructive 'Wiper' malware whose primary function is to obliterate the Master Boot Record (MBR) (`T1561.002`) and/or the Master File Table (MFT). Unlike ransomware, which encrypts data to extort money, the sole purpose of a wiper is sabotage—to render the host completely unbootable and the data permanently unrecoverable.

Understanding Killmbr (Destructive Wiper)
To an end-user, the machine suddenly blue-screens and upon reboot, displays a 'Missing Operating System' or a custom, mocking message from the attackers. For a SOC analyst, a wiper attack is a worst-case scenario, often deployed by nation-state actors (like the NotPetya or HermeticWiper attacks) to disrupt critical infrastructure or deployed by ransomware gangs to cover their tracks if a victim refuses to pay.

Execution and Destruction Mechanics
To execute its destructive payload, Killmbr *must* obtain high-level administrative or SYSTEM privileges (`T1068`). Once elevated, it uses low-level Windows APIs (like `DeviceIoControl`) to open a direct handle to the physical hard drive (e.g., `\\.\PhysicalDrive0`). It then overwrites the first sector (Sector 0, the MBR) with zeroes or random garbage. Advanced variants will also overwrite the MFT and the partition tables. When the machine inevitably reboots (often forced by the malware), the BIOS cannot locate the bootloader, effectively bricking the OS.

Indicators of Compromise & Impact
The impact is a total loss of system availability and data. Host-based IoCs include EDR alerts for a process attempting to open a handle to `\\.\PhysicalDrive0` with write permissions. Attackers often use living-off-the-land tools like `vssadmin.exe` to delete shadow copies before initiating the wipe. Once the wipe occurs, the primary indicator is the physical inability to boot the machine.

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the MITRE ATT&CK framework:

Generated Detections (Boilerplate)

These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.

YARA Rule

rule MALWARE_WIN_KILLMBR {
    meta:
        description = "Detects Killmbr (ransomware)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "killmbr" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Killmbr Activity
id: 03bf39670a7e0c1f90a80eec6ac6ca0e
status: experimental
description: Detects generic indicators of the killmbr malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*killmbr*"
    condition: selection
level: medium

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. If a wiper attack is suspected and currently in progress, IMMEDIATELY power off the machine (hard shutdown) to halt the overwriting process.
2. Do not attempt to reboot the machine normally; boot from a forensic live USB or WinPE environment to assess the damage.
3. If only the MBR is overwritten, use tools like `bootrec /fixmbr` (though advanced wipers destroy the partition table as well).
4. Restore the system from an offline, read-only backup.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not perform a graceful shutdown if you suspect a wiper; simply pull the power cord to preserve whatever data hasn't been overwritten yet.
2. Avoid relying solely on Volume Shadow Copies for recovery, as wipers almost universally delete these first.

References & External Analysis

• Search "killmbr" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: ransomware)

Explore other malware families in the same category:

• Wraut
• Scoopy
• Kgen
• Genericrxdw
• Reveton

Machine-readable

Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/api/killmbr.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.