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 the 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.

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

Sigma Rule

title: Suspicious Scribble Activity
id: b283e715491c60f770b24c63d7e01958
status: experimental
description: Detects generic indicators of the scribble malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*scribble*"
    condition: selection
level: medium

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)

Frequently Asked Questions

Related Families (Category: ransomware)

Explore other malware families in the same category:

• Dluca
• Bredavi
• Hbov
• Fadok
• Tracur

Machine-readable

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