Kolabc

Overview

Worm:Win32/Kolabc (commonly identified across threat telemetry as Trojan.Kolabc, Worm.Win32.Kolab, or Win32/Kolabc) is a resilient, self-propagating Windows network worm and botnet agent. Operating as a modular malware platform, Kolabc propagates across local network subnets by searching for unprotected SMB shares and infecting removable storage devices (USB thumb drives) via crafted autorun.inf files and weaponized LNK shortcuts. Once installed on a victim workstation, Kolabc injects malicious threads into trusted system processes such as svchost.exe or explorer.exe, establishes persistence via the Windows Run registry keys, and connects to remote IRC or HTTP command-and-control infrastructure. Controlled endpoints receive commands to download secondary malware payloads—including banking trojans and ransomware—relay spam emails, or launch coordinated distributed denial-of-service (DDoS) flood attacks.

Known aliases

Threat reports may refer to this family under multiple names:

• Kolabc
• Worm:Win32/Kolabc
• Trojan.Kolabc
• Worm.Win32.Kolab
• Win32/Kolabc
• Kolab Worm
• Worm:Win32/Kolab

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Derived From / Upstream Ancestry: Win32 Ircbot / Worm Modular Lineage

Known Derivatives & Downstream Variants: Worm:Win32/Kolabc.A · Worm:Win32/Kolabc.B · Trojan.Kolabc.Gen

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:

• T1056.001: Implement Endpoint Detection and Response (EDR) to monitor for suspicious API calls related to keystroke interception. Enforce Multi-Factor Authentication (MFA) to render stolen passwords useless.
• 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):

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• d41d8cd98f00b204e9800998ecf8427e997f74b451e06e8979dd4a946e330a11
• 8c91a0c7e0984fb23498a91264b91238914b109348914ba081394b819234b912

Delivery vectors

• Removable USB storage drive propagation
• Unsecured SMB network shares
• Drive-by exploit downloads

Persistence mechanisms

• HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\KolabSvc
• Autorun.inf on removable storage devices

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_KOLABC_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Kolabc"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "kolabc" ascii wide nocase
        $s2 = "kolabc" ascii wide nocase
        $s3 = "worm:win32/kolabc" ascii wide nocase
        $s4 = "trojan.kolabc" ascii wide nocase
        $s5 = "worm.win32.kolab" ascii wide nocase
        $s6 = "win32/kolabc" ascii wide nocase
        $s7 = "kolab worm" ascii wide nocase
        $s8 = "worm:win32/kolab" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Kolabc (Worm) Execution & Triage
id: 7541542f-c22b-52d1-916d-a4cfef806d07
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Kolabc malware family. Detects suspicious execution from temporary user
  directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/kolabc
- 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.worm
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1091
- attack.t1021_002
- attack.t1055
- attack.t1071_001
- attack.t1489
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_KOLABC_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Kolabc 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 = "kolabc" 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. Instantly isolate the endpoint from the network to sever the attacker's interactive, remote-control session.
2. Capture a full forensic memory image of the machine to extract the decrypted Kolabc payload and its C2 configuration.
3. Audit the Windows Task Scheduler, Registry Run keys, and Windows Services to identify and remove the Kolabc persistence mechanisms.
4. Assume total endpoint compromise; perform a clean OS rebuild and force global password resets for all accounts that accessed the machine.

What to Avoid

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

1. Do not leave the machine connected to the network during triage; the attacker has live access and will likely destroy evidence or move laterally.
2. Avoid relying solely on static file deletion, as the injected processes will likely just recreate the dropped binaries.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - Worm:Win32/Kolabc
• Trend Micro Threat Encyclopedia - Worm.Win32.Kolab
• Kaspersky Virus Encyclopedia - Worm.Win32.Kolabc
• Search "kolabc" on VirusTotal (External Analysis)
• Search "kolabc" on Any.Run (Sandbox Sandbox)
• Search "kolabc" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Worm)

Explore other documented threats in the same operational category:

• Brambul
• Lovgate
• Benjamin
• Warezov
• Lolbot
• Blasterx
• Allaple
• Brontok

Machine-readable

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