Reconyc

Overview

Reconyc (cataloged across security software as Trojan:Win32/Reconyc, Trojan.Win32.Reconyc, and Trojan.Reconyc) is a heavily obfuscated Windows trojan dropper and downloader first discovered around 2014. Engineered as a stealthy initial access vehicle, Reconyc is designed to penetrate perimeter defenses and stage secondary malware payloads (such as banking trojans, ransomware, and spyware) onto compromised systems. Upon initial execution, Reconyc conducts thorough environment and sandbox checks to detect virtual machine artifacts, debugging tools, and analysis environments. If safe execution parameters are confirmed, the trojan extracts an encrypted payload stored within its binary resource section, drops it into user temporary directories, and executes it. Reconyc also creates autostart registry entries under the Windows Run keys and communicates with remote C2 servers via encrypted HTTP requests to retrieve additional malicious modules.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/Reconyc
• Trojan.Win32.Reconyc
• Trojan.Reconyc
• Win32/Reconyc.A
• Reconyc Dropper

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: Win32 Obfuscated Dropper Architectures

Known Derivatives & Downstream Variants: Reconyc.A · Reconyc.Gen · Reconyc.Loader

MITRE ATT&CK Techniques

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

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.

MITRE D3FEND™ Defensive Countermeasures

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

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.

• b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3
• 8e9f0a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f

Delivery vectors

• Drive-by downloads on compromised websites distributing malicious exploit archives
• Phishing campaigns delivering password-protected ZIP droppers

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ReconycUpdate
• %TEMP%\reconyc_inst.exe

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_RECONYC_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Reconyc"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "reconyc" ascii wide nocase
        $s2 = "trojan:win32/reconyc" ascii wide nocase
        $s3 = "trojan.win32.reconyc" ascii wide nocase
        $s4 = "trojan.reconyc" ascii wide nocase
        $s5 = "win32/reconyc.a" ascii wide nocase
        $s6 = "reconyc dropper" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Reconyc (Downloader) Execution & Triage
id: 44103e0c-07f8-5594-ab52-38f877c7e97d
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Reconyc 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/reconyc
- 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.downloader
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1105
- attack.t1547_001
- attack.t1027_002
- attack.t1071_001
- attack.t1083
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_RECONYC_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Reconyc 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 = "reconyc" 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 the affected workstation from the local network to stop secondary payload retrieval.
2. Kill active Reconyc processes executing from user temporary folders.
3. Remove startup keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run\Reconyc.
4. Delete dropped binary payloads from %TEMP% and %LOCALAPPDATA%.

What to Avoid

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

1. Do not allow executable files to run unrestricted from user temp or download directories.
2. Avoid opening unverified email attachments purporting to be invoices or courier notices.

References & External Analysis

• Microsoft Defender Security Intelligence - Trojan:Win32/Reconyc
• Kaspersky Threat Intelligence - Trojan.Win32.Reconyc
• Search "reconyc" on VirusTotal (External Analysis)
• Search "reconyc" on Any.Run (Sandbox Sandbox)
• Search "reconyc" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Downloader)

Explore other documented threats in the same operational category:

• Banload
• Dofoil
• Nymaim
• Bancteian
• Aim_Downloader
• Tempedreve
• Nymeria
• Amonetize

Machine-readable

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