Palevo

Overview

Worm:Win32/Palevo (universally known in cybersecurity research as the Butterfly Bot and the Mariposa botnet) was a monumental, highly modular crimeware botnet that compromised over 12.7 million computers across 190 countries between 2008 and 2010. Authored by Slovenian malware developer Matjaž Škorjanc ('Iserdo'), the Butterfly Bot framework was sold commercially on underground forums for $500 to $2,000 to cybercrime affiliates, most notably the 'Denuvō' crew in Spain. Palevo spread aggressively via USB removable storage autorun exploits, MSN Messenger instant messaging worm propagation, and peer-to-peer file sharing networks. Infected systems were leveraged to execute massive distributed denial-of-service (DDoS) attacks, steal banking credentials, deploy browser webinjects, and install rogue security software. In December 2009, a collaborative international task force comprising the Spanish Guardia Civil, the FBI, and Panda Security executed Operation Mariposa, seizing command servers and arresting Spanish operators 'Netkairo' (Florencio Carro Ruiz), 'Ostiator', and 'Johny-K'. In July 2010, Slovenian police and the FBI arrested author Matjaž Škorjanc in Maribor, leading to his federal indictment and conviction in the District of Columbia.

Known aliases

Threat reports may refer to this family under multiple names:

• Palevo
• Worm:Win32/Palevo
• Butterfly Bot
• Mariposa
• Rkit.Palevo

Threat Actor Attribution

Attribution is probabilistic, not a science. Each link below states its confidence level and the evidence behind it.

• Matjaž Škorjanc (Iserdo, Author) High confidence
  Basis:
• Spanish Denuvō Group (Netkairo) High confidence
  Basis:

Family Pedigree & Lineage

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

Known Derivatives & Downstream Variants: Butterfly Bot V1 · Mariposa Core · Yahos (Facebook Worm Derivative)

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:

• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
• T1185: Enforce strong MFA and use browser isolation or hardened browsers for sensitive financial or administrative portals to defeat session hijacking.
• T1566.002: Inspect email links for known malicious domains and use link-rewriting services for time-of-click analysis.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Exploited Vulnerabilities (CVEs)

This malware family is documented weaponizing the following common vulnerabilities and exposures:

• CVE-2008-4250 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2010-2568 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).

Command & Control (C2) and Network Profile

How this family talks to its operators. C2 traffic can often identify a family even when its code and configuration are hard to analyse. Ports and patterns are historical and change between campaigns, so use them as hunting leads rather than block-only rules.

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.

• 4b6f756ce1bc7b2675685938bf8c679237000d02ee0761e065e1db5451996df7
• 93ab0a927ec0bc1d34c2ab79d67e5ff825c88b64e5257e841893d5f308e7ef9e

Delivery vectors

• usb_autorun
• instant_messaging_links
• p2p_networks

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run
• Explorer Injection

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_PALEVO_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Palevo"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "palevo" ascii wide nocase
        $s2 = "palevo" ascii wide nocase
        $s3 = "worm:win32/palevo" ascii wide nocase
        $s4 = "butterfly bot" ascii wide nocase
        $s5 = "mariposa" ascii wide nocase
        $s6 = "rkit.palevo" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Palevo (Botnet) Execution & Triage
id: 04e842e3-a710-5933-bdab-3a8899160226
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Palevo malware family. Detects firewall rule subversion, internal port
  proxying, and command-and-control keepalive polling indicative of botnet nodes.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/palevo
- https://malware-families-catalog.systemhelpdesk.com/defensive/botnet-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.botnet
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1091
- attack.t1566_002
- attack.t1055
- attack.t1185
- attack.t1071_001
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \netsh.exe
    - \route.exe
    - \arp.exe
    - \ping.exe
    CommandLine|contains:
    - advfirewall firewall add rule
    - netsh interface portproxy
    - ping -n 1 127.0.0.1
  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_PALEVO_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Palevo 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 = "palevo" 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. Disable Windows USB Autorun and AutoPlay globally via Group Policy (GPO).
2. Block outbound HTTP communication matching known Palevo dynamic DNS domains.
3. Isolate infected hosts to prevent lateral spread across local network shares.
4. Apply security patch MS08-067 to prevent unauthenticated remote code execution via Server Service.

What to Avoid

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

1. Never insert unverified USB flash drives into corporate endpoints without hardware sanitization.
2. Avoid clicking unsolicited shortened links sent via collaborative chat or messaging software.
3. Do not allow unprivileged users to execute files from removable media.

References & External Analysis

• FBI Press Release: Butterfly Bot Mastermind Convicted in International Cyber Conspiracy
• Spanish Guardia Civil & Panda Security: Operation Mariposa Technical Report
• NIST National Vulnerability Database CVE-2008-4250
• Search "palevo" on VirusTotal (External Analysis)
• Search "palevo" on Any.Run (Sandbox Sandbox)
• Search "palevo" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Botnet)

Explore other documented threats in the same operational category:

• Dorkbot
• Tordev
• Simda
• Cutwail
• Storm
• Cybernetic
• Glupteba
• Stantinko

Machine-readable

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