Cerbu

Overview

Cerbu (cataloged across security vendors under detections including Backdoor:Win32/Cerbu, Trojan:Win32/Cerbu, and Win32/Cerbu) is a covert Windows remote access trojan and backdoor active since 2013. Infiltrating endpoints primarily through deceptive freeware installers, weaponized phishing email attachments, and compromised website drive-by downloads, Cerbu establishes unauthorized background access to victim machines. Upon execution, Cerbu copies its executable stub into hidden user directories (such as %AppData% or %Temp%) and secures persistence via Windows Registry Run keys and scheduled tasks. The backdoor establishes encrypted command-and-control communication with attacker-controlled servers, allowing unauthorized operators to execute arbitrary shell commands, exfiltrate confidential files, harvest web browser credentials and session tokens, log user keystrokes, and download secondary malware frameworks.

Known aliases

Threat reports may refer to this family under multiple names:

• Backdoor:Win32/Cerbu
• Trojan:Win32/Cerbu
• Win32/Cerbu

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: Generic Win32 Backdoors

Known Derivatives & Downstream Variants: Cerbu.A · Cerbu.B

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:

• 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.

• 4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c
• 9a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b

Delivery vectors

• invoice_doc.exe
• cerbu_setup.exe

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\CerbuSvc
• %AppData%\Cerbu\cerbu_client.exe

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_CERBU_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Cerbu"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "cerbu" ascii wide nocase
        $s2 = "backdoor:win32/cerbu" ascii wide nocase
        $s3 = "trojan:win32/cerbu" ascii wide nocase
        $s4 = "win32/cerbu" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Cerbu (Backdoor) Execution & Triage
id: ff3c8a80-aed1-51d5-b559-7a4dfb436d62
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Cerbu malware family. Detects proxy execution, reflective DLL loading,
  and remote command injection associated with modular enterprise backdoors.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/cerbu
- https://malware-families-catalog.systemhelpdesk.com/defensive/backdoor-rat-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.backdoor
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1566_001
- attack.t1059_003
- attack.t1547_001
- attack.t1056_001
- attack.t1113
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \powershell.exe
    - \cmd.exe
    - \rundll32.exe
    - \regsvr32.exe
    CommandLine|contains:
    - DownloadString
    - IEX(
    - '/s /n /u /i:'
    - sc create
    - start-process
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: high

rule MALWARE_WIN_CERBU_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Cerbu 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 = "cerbu" 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 Cerbu payload and its C2 configuration.
3. Audit the Windows Task Scheduler and Registry Run keys to identify and remove the Cerbu persistence mechanisms.
4. Assume total endpoint compromise; perform a clean OS rebuild and force 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 manual file deletion, as the injected processes will likely just recreate the dropped binaries.

References & External Analysis

• Microsoft Defender Security Intelligence - Backdoor:Win32/Cerbu
• CISA Cybersecurity Advisories & Threat Telemetry
• Search "cerbu" on VirusTotal (External Analysis)
• Search "cerbu" on Any.Run (Sandbox Sandbox)
• Search "cerbu" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Backdoor)

Explore other documented threats in the same operational category:

• Rozena
• Bersek
• Orcusrot
• Bagle
• Tick
• Hacdef
• Vixenpanda
• Rbot

Machine-readable

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