Scribble

Overview

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.

Understanding Macro Downloaders (Scribble)
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.

Execution and Payload Delivery Mechanics
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.

Indicators of Compromise & Impact
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.

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:

• T1059.005: Restrict execution of scripting languages such as PowerShell, VBScript, or Python to authorized administrators. Enforce Script Block Logging.
• 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):

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_SCRIBBLE_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Scribble"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "scribble" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Scribble (Ransomware) Execution & Triage
id: 23658366-f91e-5ae6-8d8d-098cc897652d
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Scribble malware family. Detects volume shadow copy deletion, boot status
  tampering, and recovery inhibition characteristic of modern ransomware operations.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/scribble
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-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.ransomware
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1059_005
- attack.t1105
- attack.t1027
- attack.t1204_002
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \vssadmin.exe
    - \wmic.exe
    - \wbadmin.exe
    - \bcdedit.exe
    CommandLine|contains:
    - delete shadows
    - shadowcopy delete
    - resize shadowstorage
    - recoveryenabled no
    - ignoreallfailures
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: critical

rule MALWARE_WIN_SCRIBBLE_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Scribble 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 = "scribble" 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 endpoint immediately to prevent the downloaded payload from executing or spreading laterally.
2. Examine the EDR process tree to determine exactly what payload `powershell.exe` or `cmd.exe` downloaded and executed.
3. Extract the malicious macro (using tools like `olevba`) to identify the C2 URLs, and block them enterprise-wide.
4. Use email security gateways to identify and purge the original phishing email from all other user inboxes to prevent further infections.

What to Avoid

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

1. 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).
2. 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.

References & External Analysis

• Search "scribble" on VirusTotal (External Analysis)
• Search "scribble" on Any.Run (Sandbox Sandbox)
• Search "scribble" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Sokuxuan
• Potukorp
• Hg8Absxocmcj
• Genericrxet
• Smalo
• Crysis
• Jigsaw
• Genericrxcr

Machine-readable

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