Vbcryptor

Overview

Ransomware:Win32/Vbcryptor is a broad detection name applied to various strains of ransomware, file encoders, and malicious crypters that are compiled using Microsoft Visual Basic (VB) or Visual Basic .NET (VB.NET). Because VB executables are often heavily dependent on the .NET framework and are relatively easy to decompile, malware authors use 'Vbcryptor' wrapper tools to heavily obfuscate their actual payloads, making static analysis extremely difficult.

Understanding Vbcryptor (Visual Basic Crypters)
To an end-user, an encounter with Vbcryptor usually ends in tragedy: personal files are suddenly appended with strange extensions (like `.locked` or `.crypto`), and a ransom note demands cryptocurrency to restore access. For a malware analyst, encountering a Vbcryptor file means the first step is unpacking. The outer VB layer is rarely the actual ransomware; instead, it is a highly obfuscated 'packer' or 'crypter' designed solely to evade antivirus (`T1027.002`). The true payload (which could be anything from a banking trojan to a well-known ransomware family like Locky or Cerber) is hidden inside, encrypted.

Execution and Unpacking Mechanics
Vbcryptor variants are distributed via phishing (`T1566.001`), drive-by downloads, or RDP brute-forcing. Upon execution (`T1204.002`), the VB executable loads into memory. It then executes a decryption routine to unpack its hidden payload directly into a hollowed-out process (Process Hollowing - `T1055.012`) like `svchost.exe` or `vbc.exe`. By running the payload exclusively in memory, the malware avoids dropping the true ransomware binary to the disk, bypassing many legacy, signature-based AV scanners. Once the hidden ransomware executes, it begins iterating through local and network drives (`T1083`), encrypting user files (`T1486`).

Indicators of Compromise & Impact
The impact is catastrophic data loss or severe operational downtime. Host-based IoCs include anomalous child processes spawning from generic Windows executables, mass file modifications (`T1486`), and the dropping of ransom notes (e.g., `DECRYPT_FILES.txt`). Network IoCs may include the payload attempting to communicate with Tor gateways or known C2 infrastructure.

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

Sigma Rule

title: Suspicious Vbcryptor Activity
id: 6a0e93d27ee3426e089bcde4c0e03e29
status: experimental
description: Detects generic indicators of the vbcryptor malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*vbcryptor*"
    condition: selection
level: medium

Containment & Response Steps

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

1. Immediately disconnect the infected endpoint from the network (unplug ethernet, disable Wi-Fi) to stop the ransomware from encrypting shared network drives.
2. Do not immediately reboot the machine; if the ransomware is currently executing, a reboot might destroy the encryption keys temporarily held in RAM.
3. Capture a full memory dump; analysts can often extract the unpacked payload and sometimes the encryption keys directly from the hollowed process.
4. Restore affected files from an offline, verified backup solution.

What to Avoid

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

1. Do not pay the ransom; paying funds criminal organizations and there is no guarantee the decryptor provided will actually work.
2. Avoid relying on static AV scans of the original Vbcryptor file; the outer VB shell is often highly polymorphic and changes its hash constantly.

References & External Analysis

• Search "vbcryptor" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: ransomware)

Explore other malware families in the same category:

• Gendwnurl
• Redlonam
• Hidcon
• Honk
• Emotetn

Machine-readable

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