Vbkryjetor

Overview

Vbkryjetor (identified across commercial security telemetry as Packer:Win32/Vbkryjetor, Trojan:Win32/Vbkryjetor, and Crypter.Vbkryjetor) is a specialized Visual Basic-based software obfuscator, crypter, and runtime packer extensively abused by cybercriminal threat actors. Its primary function is to shield commodity malware families—including remote access trojans (RATs like njRAT and DarkComet), infostealers, and keyloggers—from static antivirus detection and automated sandbox analysis. Vbkryjetor wraps malicious payloads inside multi-layered encrypted resources and decoy Visual Basic 6 code blocks. During initial execution, Vbkryjetor evaluates system parameters to detect virtual machines, debugging environments, and sandbox hooks. If defensive instrumentation is absent, the packer dynamically allocates executable memory, decrypts the embedded payload using custom XOR or RC4 algorithms, and injects it into legitimate Windows processes (such as svchost.exe or explorer.exe) via process hollowing.

Known aliases

Threat reports may refer to this family under multiple names:

• Packer:Win32/Vbkryjetor
• Trojan:Win32/Vbkryjetor
• Crypter.Vbkryjetor
• Win32/Vbkryjetor.Packer
• Trojan.VB.Kryjetor

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Derived From / Upstream Ancestry: Visual Basic Crypter Frameworks

Known Derivatives & Downstream Variants: Vbkryjetor.A · Vbkryjetor.B · Vbkryjetor.Gen

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Exploited Vulnerabilities (CVEs)

This malware family is documented weaponizing the following common vulnerabilities and exposures:

• CVE-2012-0158 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2017-11882 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• 5c4d3e2b1a0f9e8d7c6b5a4f3e2d1c0b9a8f7e6d5c4b3a2f1e0d9c8b7a6f5e4d
• 3b2a1c0f9e8d7c6b5a4f3e2d1c0b9a8f7e6d5c4b3a2f1e0d9c8b7a6f5e4d3c2b

Delivery vectors

• Phishing emails with malicious Office attachments exploiting CVE-2017-11882
• Compromised software distribution portals and torrent-delivered utility installers

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run entry pointing to packed payload binary
• Process injection into svchost.exe or explorer.exe executing continuously across user sessions

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_VBKRYJETOR_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Vbkryjetor"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "vbkryjetor" ascii wide nocase
        $s2 = "packer:win32/vbkryjetor" ascii wide nocase
        $s3 = "trojan:win32/vbkryjetor" ascii wide nocase
        $s4 = "crypter.vbkryjetor" ascii wide nocase
        $s5 = "win32/vbkryjetor.packer" ascii wide nocase
        $s6 = "trojan.vb.kryjetor" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Vbkryjetor (Packer) Execution & Triage
id: 8acb5584-0e52-51b9-b81c-7df980afc6eb
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Vbkryjetor malware family. Detects suspicious execution from temporary
  user directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/vbkryjetor
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.packer
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1027_002
- attack.t1055_012
- attack.t1497_001
- attack.t1112
- attack.t1106
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_VBKRYJETOR_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Vbkryjetor tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "vbkryjetor" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

Containment & Response Steps

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

1. Isolate endpoints displaying unexpected process injection or hollowed legitimate Windows processes.
2. Terminate suspicious host processes executing out of temporary or non-standard user profile paths.
3. Capture volatile physical memory to dump decrypted underlying trojan payloads for malware reverse engineering.
4. Audit firewall logs for anomalous outbound C2 communication originating from hollowed system executables.

What to Avoid

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

1. Do not rely solely on static file hashes for detection, as crypters produce unique hashes for every packed binary.
2. Avoid analyzing samples in unsophisticated sandboxes, as Vbkryjetor detects virtual machine artifacts and remains dormant.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - Packer:Win32/Vbkryjetor Details
• Trend Micro Threat Encyclopedia - Packer.Win32.Vbkryjetor
• NIST National Vulnerability Database - CVE-2017-11882
• Search "vbkryjetor" on VirusTotal (External Analysis)
• Search "vbkryjetor" on Any.Run (Sandbox Sandbox)
• Search "vbkryjetor" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Packer)

Explore other documented threats in the same operational category:

• Packedent
• Confuser
• Packy
• Flystudio
• Multipacked
• Noobyprotect
• Enigmaprotector
• Obsidium

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/vbkryjetor.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.