Rewriteboota

Overview

Trojan:Win32/Rewriteboota is a highly destructive trojan classified as a 'Bootkit' or MBR (Master Boot Record) infector. Its primary objective is not necessarily to steal data, but to establish the deepest possible level of persistence or to cause catastrophic denial of service by overwriting the critical boot sectors of the infected hard drive, rendering the operating system unbootable (`T1561.001`).

Understanding Rewriteboota (MBR Infectors)
To an end-user, the impact of Rewriteboota is immediate and catastrophic: upon restarting their computer, instead of Windows loading, they are met with a black screen, a custom ransom message, or a 'No bootable device found' error. For a security responder, a bootkit represents one of the most difficult infections to remediate, as the malware executes before the operating system and its security tools even load.

Execution and Destruction Mechanics
Rewriteboota requires administrative privileges to execute. Once running, it uses low-level disk access APIs (such as `DeviceIoControl`) to bypass the Windows filesystem entirely and write directly to the physical sectors of the hard drive (`T1014`). It targets Sector 0, the Master Boot Record. It may overwrite the MBR with a malicious bootloader that loads the malware into memory before Windows starts (establishing deep persistence), or it may simply overwrite it with garbage data or a ransom note (causing denial of service). This technique completely bypasses traditional file-based antivirus scanning.

Indicators of Compromise & Impact
The primary impact is a completely unbootable system and potential total data loss (if the partition table is also destroyed). Host-based IoCs are difficult to detect while the OS is running, but advanced EDR solutions may flag anomalous processes attempting raw disk access (`\.\PhysicalDrive0`). The most obvious IoC is the failure of the system to boot, or the display of a non-standard message during the POST sequence.

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_REWRITEBOOTA {
    meta:
        description = "Detects Rewriteboota (trojan)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "rewriteboota" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Rewriteboota Activity
id: d1e59df683f4ae4230f373e9a13c1ee0
status: experimental
description: Detects generic indicators of the rewriteboota malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*rewriteboota*"
    condition: selection
level: medium

Containment & Response Steps

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

1. If the system is still running but raw disk access alerts have fired, do NOT reboot the machine. Capture a live memory image and attempt to block the process.
2. If the system is already unbootable, boot from a clean Windows Installation USB or a WinPE recovery environment.
3. Use the Windows Recovery Environment command prompt and run `bootrec /fixmbr` and `bootrec /fixboot` to attempt to repair the Master Boot Record.
4. If the partition table was destroyed, specialized data recovery software (or restoring from a full image backup) will be necessary.

What to Avoid

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

1. Do not blindly reboot a machine if EDR alerts indicate a potential MBR modification; this will trigger the destructive payload.
2. Avoid paying a ransom if a message is displayed at boot; MBR lockers are notoriously buggy and paying rarely results in recovery.

References & External Analysis

• Search "rewriteboota" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: trojan)

Explore other malware families in the same category:

• Xorer
• Rozena
• Diskwriter
• Ciadoor
• Virledi

Machine-readable

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