{
  "family": "scribble",
  "sample_count": 4,
  "category": "ransomware",
  "description": "TrojanDownloader:O97M/Scribble (or similar macro-based droppers) represents a prevalent technique for initial access: the weaponization of Microsoft Office documents (Word, Excel) using malicious Visual Basic for Applications (VBA) macros. Scribble is not the final payload; rather, it is a heavily obfuscated script designed to execute when the user opens the document and enables content, securely downloading a secondary, severe threat like Emotet, Trickbot, or ransomware.<br><br><b>Understanding Macro Downloaders (Scribble)</b><br>To an end-user, the attack arrives as a seemingly urgent email (an invoice, a resume, a shipping notice) with an attached Office document. When opened, the document often displays a 'lure'—a blurry image or fake security warning—instructing the user to click 'Enable Content' or 'Enable Macros' to view the text. For a SOC analyst, this is the classic, highly effective initial breach vector relying entirely on social engineering.<br><br><b>Execution and Payload Delivery Mechanics</b><br>The attack begins with a spear-phishing email (`T1566.001`). The attached document contains malicious VBA code (`T1059.005`). To evade static AV analysis, the macro code is heavily obfuscated (`T1027`), often using string reversal, junk code insertion, and dynamic execution (e.g., using `ExecuteExcel4Macro` or building strings at runtime). Once the user enables macros (`T1204.002`), the VBA script executes. It typically spawns hidden instances of legitimate 'Living off the Land' (LotL) binaries like `powershell.exe`, `cmd.exe`, or `wscript.exe` (`T1059.001`). These system tools are passed obfuscated command-line arguments instructing them to reach out to a hardcoded URL (`T1105`), download the final payload (often an `.exe` or `.dll`), and execute it.<br><br><b>Indicators of Compromise & Impact</b><br>The impact depends entirely on the downloaded payload (frequently ransomware or banking trojans). Host-based IoCs are highly visible in EDR: analysts will see Office applications (`WINWORD.EXE`, `EXCEL.EXE`) exhibiting anomalous behavior, specifically spawning child processes like `powershell.exe` or `cmd.exe` that make outbound HTTP/HTTPS connections. Network IoCs include the outbound connection to the C2 server to retrieve the payload.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Scribble and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Scribble is classified as a Ransomware. 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 Scribble establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Scribble 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 Scribble compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Scribble 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 cryptographic algorithms and file targeting techniques does Scribble employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Scribble typically leverages hybrid cryptographic architectures combining symmetric stream or block ciphers (such as AES-256 or ChaCha20) for rapid file encryption with asymmetric algorithms (such as RSA-2048 or Curve25519) to securely protect the session keys. It aggressively targets sensitive file extensions including corporate documents, databases, virtual disks, and backups while systematically executing commands to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) and disable system recovery options."
      }
    },
    {
      "@type": "Question",
      "name": "Are decryptors available for Scribble, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Scribble depends on whether security researchers or law enforcement (such as the No More Ransom initiative) have recovered the master private keys or discovered flaws in its key generation routines. Victims should never pay the extortion demand, as payment fuels criminal operations without guaranteeing file restoration. The recommended recovery procedure entails isolating infected hosts, conducting forensic disk imaging, identifying the root access vector, and restoring validated systems from immutable offline backups."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1059.005",
    "T1105",
    "T1027",
    "T1204.002"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1059.005",
      "name": "Command and Scripting Interpreter: Visual Basic (Malicious Macros)",
      "tactic": "Execution"
    },
    {
      "id": "T1204.002",
      "name": "User Execution: Malicious File (Enabling macros)",
      "tactic": "Execution"
    },
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information (Obfuscated VBA code)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer (Downloading the final payload)",
      "tactic": "Command and Control"
    }
  ],
  "containment_steps": [
    "Isolate the endpoint immediately to prevent the downloaded payload from executing or spreading laterally.",
    "Examine the EDR process tree to determine exactly what payload `powershell.exe` or `cmd.exe` downloaded and executed.",
    "Extract the malicious macro (using tools like `olevba`) to identify the C2 URLs, and block them enterprise-wide.",
    "Use email security gateways to identify and purge the original phishing email from all other user inboxes to prevent further infections."
  ],
  "what_to_avoid": [
    "Do not allow macros to execute universally across the enterprise; strictly enforce Group Policies that disable macros for files originating from the internet (Mark of the Web).",
    "Avoid relying solely on scanning the `.doc` or `.xls` file; dynamic analysis (sandboxing) is required to observe the PowerShell execution and capture the C2 traffic."
  ],
  "target_industries": [
    "Healthcare",
    "Critical Infrastructure",
    "Enterprise"
  ],
  "motivation": "Financial Extortion",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "defense_evasion",
    "impact"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}