Delfidelfi

Overview

Trojan:Win32/Delfidelfi is a generic heuristic detection used by antivirus engines to classify a wide variety of malware that has been written or heavily packed using the **Delphi** programming language (or specifically, the Embarcadero Delphi IDE). Delphi is highly favored by malware authors in certain regions (particularly South America and Eastern Europe) for writing banking trojans, RATs, and crypters because it compiles to standalone, dependency-free executables that are easy to obfuscate.

Understanding the Delphi Threat Landscape
To an end-user, the infection is invisible until the payload executes. For a security analyst, a Delfidelfi detection indicates the presence of a compiled executable actively attempting to evade analysis (`T1027`). Because this is a generic detection based on the language/compiler fingerprint and suspicious API calls, the actual threat could range from a simple keylogger to a sophisticated, multi-stage banking trojan like Grandoreiro or Mekotio.

Execution and Evasion Mechanics
Delfidelfi-flagged malware is frequently distributed via localized phishing campaigns containing weaponized ZIP or ISO files (`T1566.001`). When the user executes the Delphi binary (`T1204.002`), it often employs massive, bloated resource sections (sometimes pushing the file size over 100MB) to break standard AV emulator sandboxes (`T1497.001`). Once executing, Delphi trojans heavily utilize API hooking and process injection (`T1055`) to intercept credentials from web browsers (`T1555.003`) and establish persistence via the Registry Run keys or Startup folders (`T1547.001`).

Indicators of Compromise & Impact
The impact depends entirely on the specific payload, but Delphi malware frequently targets financial credentials. Host-based IoCs include EDR alerts for newly created, unusually large executables (often disguised as PDF or Excel icons) in the user's `AppData` folder. Network IoCs often involve outbound traffic to compromised WordPress sites or cloud storage providers (Dropbox/Azure) used as C2 infrastructure. Statically analyzing the file will reveal classic Delphi compiler artifacts (e.g., strings like `PACKAGEINFO`, `TApplication`).

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the MITRE ATT&CK framework:

Tactical Mitigations

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

• T1566.001: Scan email attachments for malicious macros, scripts, or suspicious archive files.

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

Sigma Rule

title: Suspicious Delfidelfi Activity
id: 361a5dc4158ce8e5b271184c6632fc76
status: experimental
description: Detects generic indicators of the delfidelfi malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*delfidelfi*"
    condition: selection
level: medium

Containment & Response Steps

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

1. Treat the detection as a high-severity threat, as Delphi is the primary language for devastating banking trojans.
2. Isolate the endpoint and utilize EDR to trace the execution chain to identify any secondary payloads downloaded or injected.
3. Submit the executable to a specialized malware sandbox for dynamic analysis, ensuring the sandbox can handle artificially bloated file sizes.
4. If banking portals were accessed during the infection window, force an immediate password reset and closely monitor the accounts for fraudulent activity.

What to Avoid

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

1. Do not assume the file is benign simply because it is large; file bloating is a specific tactic to bypass AV scanning limits.
2. Avoid relying on static analysis alone; Delphi malware frequently decrypts its core logic only during runtime.

References & External Analysis

• Search "delfidelfi" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: trojan)

Explore other malware families in the same category:

• Hmgfa45Id4O
• Collector
• Kwampirs
• Netshadow
• Look2Me

Machine-readable

Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/delfidelfi.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.