Disfa

Overview

Disfa (cataloged in antivirus telemetry as Trojan:Win32/Disfa, Trojan.MSIL.Disfa, and recognized as a variant of the Bladabindi / njRAT malware family) is a .NET-based remote access trojan (RAT) and information stealer discovered in circulation around 2013. Developed in Microsoft Intermediate Language (MSIL), Disfa allows threat actors to establish complete remote control over compromised Windows endpoints through encrypted reverse TCP connections. Upon execution, Disfa copies its payload into %APPDATA%, creates autostart registry entries under the Windows Run key, and establishes API hooks to capture user keystrokes, clipboard contents, and stored web browser credentials. In addition to info-stealing capabilities, Disfa features modular remote administration functions, including live webcam and microphone surveillance, remote desktop viewing, command shell execution, registry manipulation, and the capability to download and execute secondary malware payloads.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/Disfa
• Trojan.MSIL.Disfa
• Backdoor:MSIL/Bladabindi
• Disfa.RAT
• Win32/Disfa

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: Bladabindi / Njrat Framework

Known Derivatives & Downstream Variants: Disfa.A · Disfa.Msil · Disfa.Gen

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:

• T1056.001: Implement Endpoint Detection and Response (EDR) to monitor for suspicious API calls related to keystroke interception. Enforce Multi-Factor Authentication (MFA) to render stolen passwords useless.
• T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.
• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
• T1113: Monitor for frequent or unauthorized screen captures or clipboard reads. Restrict background applications from accessing desktop APIs.

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.

• f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2
• 5b6c7d8e9f0a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c

Delivery vectors

• Phishing emails with compressed ZIP archives containing compiled .NET executables
• Malicious USB drive infection leveraging deceptive shortcut links

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\DisfaService
• %APPDATA%\Disfa\disfa_srv.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_DISFA_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Disfa"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "disfa" ascii wide nocase
        $s2 = "trojan:win32/disfa" ascii wide nocase
        $s3 = "trojan.msil.disfa" ascii wide nocase
        $s4 = "backdoor:msil/bladabindi" ascii wide nocase
        $s5 = "disfa.rat" ascii wide nocase
        $s6 = "win32/disfa" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Disfa (Trojan) Execution & Triage
id: bb40e310-dd26-5ad1-add3-78ca377adcd5
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Disfa 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/disfa
- 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.t1056_001
- attack.t1113
- 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_DISFA_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Disfa 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 = "disfa" 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 infected endpoint from the network to terminate active reverse TCP command sessions.
2. Identify and kill active .NET executable processes running from %APPDATA% or %TEMP%.
3. Remove startup registry entries under HKCU\Software\Microsoft\Windows\CurrentVersion\Run.
4. Rotate all corporate, email, and banking credentials accessed from the infected workstation.

What to Avoid

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

1. Do not execute suspicious executable attachments received from unverified email senders.
2. Avoid inserting unencrypted USB drives into workstations without endpoint scanning enabled.

References & External Analysis

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

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Imqaaem1Agai
• Enfal
• Garrun
• Look2Me
• Wizrem
• Keylogr
• Infinitetear
• Infector_Ng_2004

Machine-readable

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