{
  "family": "delfidelfi",
  "sample_count": 6,
  "category": "trojan",
  "description": "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.<br><br><b>Understanding the Delphi Threat Landscape</b><br>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.<br><br><b>Execution and Evasion Mechanics</b><br>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`).<br><br><b>Indicators of Compromise & Impact</b><br>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`).",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Delfidelfi and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Delfidelfi is classified as a Trojan. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments."
      }
    },
    {
      "@type": "Question",
      "name": "How does Delfidelfi establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Delfidelfi typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks."
      }
    },
    {
      "@type": "Question",
      "name": "What are the essential incident response steps for mitigating a Delfidelfi compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Delfidelfi should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups."
      }
    },
    {
      "@type": "Question",
      "name": "What secondary payloads and staging behaviors are commonly associated with Delfidelfi?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Delfidelfi frequently operates as a loader or dropper designed to establish a foothold before downloading and executing secondary high-impact malware payloads. Depending on the threat actor's objectives, these dropped modules can range from ransomware and banking injects to modular infostealers and remote management backdoors."
      }
    },
    {
      "@type": "Question",
      "name": "How can security operations teams effectively detect and hunt for Delfidelfi across enterprise endpoints?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Defenders should hunt for Delfidelfi by deploying behavioral endpoint detection and response (EDR) rules that monitor suspicious process spawning (such as cmd.exe or powershell.exe spawned from office documents or temporary directories), anomalous outbound network connections from non-browser binaries, and unauthorized modifications to Windows Run keys and scheduled task registries."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1566.001",
    "T1204.002",
    "T1055",
    "T1027"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information (Delphi packing/bloating)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1055",
      "name": "Process Injection (Common in Delphi banking trojans)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1566.001",
      "name": "Phishing: Spearphishing Attachment",
      "tactic": "Initial Access"
    },
    {
      "id": "T1204.002",
      "name": "User Execution: Malicious File",
      "tactic": "Execution"
    }
  ],
  "containment_steps": [
    "Treat the detection as a high-severity threat, as Delphi is the primary language for devastating banking trojans.",
    "Isolate the endpoint and utilize EDR to trace the execution chain to identify any secondary payloads downloaded or injected.",
    "Submit the executable to a specialized malware sandbox for dynamic analysis, ensuring the sandbox can handle artificially bloated file sizes.",
    "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": [
    "Do not assume the file is benign simply because it is large; file bloating is a specific tactic to bypass AV scanning limits.",
    "Avoid relying on static analysis alone; Delphi malware frequently decrypts its core logic only during runtime."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "execution",
    "persistence"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows 7"
  ]
}