Shelma

Overview

Shelma (cataloged across security vendors and threat intelligence databases under signatures including Trojan:Win32/Shelma, Trojan.Win32.Shelma, and Backdoor:Win32/Shelma) is a modular Delphi-based Windows trojan dropper and surveillance backdoor active since 2014. Distributed primarily through trojanized software cracks, game activators, and malicious torrent bundles, Shelma functions as an initial-stage compromise platform. Upon execution, the malware establishes persistence by writing autostart values to HKCU\Software\Microsoft\Windows\CurrentVersion\Run and copies itself to the Windows AppData directory under randomized process names. Shelma interrogates the host operating system to identify active antivirus products, virtualization flags, and network interfaces. Once host fingerprinting is complete, it connects to remote command-and-control servers using encrypted HTTP/TCP sockets, downloading and executing secondary malicious payloads—ranging from cryptocurrency miners to banking info-stealers and credential harvest tools.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/Shelma
• Trojan.Win32.Shelma
• Backdoor:Win32/Shelma
• Win32/Shelma

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: Delphi Trojan Dropper Framework

Known Derivatives & Downstream Variants: Shelma.A · Shelma.B

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:

• 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.

• 293a4b5c6d7e8f90123456789abcdef0123456789abcdef0123456789abcdef01
• 3a4b5c6d7e8f90123456789abcdef0123456789abcdef0123456789abcdef012

Delivery vectors

• game_trainer_keygen.exe
• photoshop_activation_tool.exe

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ShelmaHost

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_SHELMA_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Shelma"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "shelma" ascii wide nocase
        $s2 = "trojan:win32/shelma" ascii wide nocase
        $s3 = "trojan.win32.shelma" ascii wide nocase
        $s4 = "backdoor:win32/shelma" ascii wide nocase
        $s5 = "win32/shelma" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Shelma (Trojan) Execution & Triage
id: 30afcf4e-7c26-563e-97eb-5f2a9ea600b3
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Shelma 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/shelma
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-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.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1059_003
- attack.t1547_001
- attack.t1105
- attack.t1082
- attack.t1071_001
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_SHELMA_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Shelma 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 = "shelma" 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. Instantly isolate the endpoint from the network to sever the attacker's interactive, remote-control session.
2. Capture a full forensic memory image of the machine to extract the decrypted Shelma payload and its C2 configuration.
3. Audit the Windows Task Scheduler and Registry Run keys to identify and remove the Shelma persistence mechanisms.
4. Assume total endpoint compromise; perform a clean OS rebuild and force password resets for all accounts that accessed the machine.

What to Avoid

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

1. Do not leave the machine connected to the network during triage; the attacker has live access and will likely destroy evidence or move laterally.
2. Avoid relying solely on manual file deletion, as the injected processes will likely just recreate the dropped binaries.

References & External Analysis

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

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Mapstosteal
• Gampass
• Rasoon
• Phonerooter
• Dnschanger
• Xxybvi
• Doser
• Wi0Abyrjybki

Machine-readable

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