Pykspa

Overview

Pykspa (cataloged across threat intelligence as W32/Pykspa, Worm:Win32/Pykspa, and the Skype Worm Pykspa) is an information-stealing worm that first emerged in 2008, specifically designed to propagate across Skype peer networks. Pykspa hijacks active Skype sessions to send automated spam messages containing malicious download links to all user contacts. To maximize click-through rates, Pykspa checks the victim's Skype interface language and delivers localized social engineering lures. Once executed on a recipient's endpoint, Pykspa extracts personal information, steals cached credentials, and communicates with command-and-control servers using a high-velocity Domain Generation Algorithm (DGA). As extensively documented by Akamai Threat Research and Fraunhofer FKIE's Malpedia, Pykspa generates thousands of pseudorandom DNS requests daily, creating significant network noise and ensuring C2 survivability against domain seizures.

Known aliases

Threat reports may refer to this family under multiple names:

• W32/Pykspa
• Worm:Win32/Pykspa
• Skype Worm Pykspa
• W32.Pykspa
• Win32/Pykspa.Worm

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: Instant Messaging Worm Engines

Known Derivatives & Downstream Variants: Pykspa.A · Pykspa.B · Pykspa.Dga

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.
• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
• 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):

Exploited Vulnerabilities (CVEs)

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

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

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.

• b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5f6a7b8c9
• 2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a

Delivery vectors

• Automated instant messaging spam links sent via hijacked Skype accounts
• Removable USB drive propagation exploiting Windows shortcut vulnerability CVE-2010-2568

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\PykspaWorm
• Scheduled task registered under Windows Task Scheduler as 'PykspaUpdate'

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_PYKSPA_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Pykspa"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "pykspa" ascii wide nocase
        $s2 = "w32/pykspa" ascii wide nocase
        $s3 = "worm:win32/pykspa" ascii wide nocase
        $s4 = "skype worm pykspa" ascii wide nocase
        $s5 = "w32.pykspa" ascii wide nocase
        $s6 = "win32/pykspa.worm" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Pykspa (Worm) Execution & Triage
id: 80a2a1e4-f76a-5305-8919-acde253b0f3f
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Pykspa 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/pykspa
- 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.t1071_001
- attack.t1568_002
- attack.t1547_001
- attack.t1056_001
- attack.t1105
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_PYKSPA_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Pykspa 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 = "pykspa" 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. Disconnect infected machines from local networks to stop instant messaging propagation across contact lists.
2. Kill rogue processes spawned by Pykspa and terminate unauthorized Skype API hooks.
3. Remove autostart registry entries under HKCU\Software\Microsoft\Windows\CurrentVersion\Run.
4. Implement DNS sinkholing for identified DGA algorithm domain seed patterns.

What to Avoid

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

1. Do not click unsolicited file download links sent over instant messaging applications, even from known contacts.
2. Avoid allowing unmonitored DNS queries to resolve thousands of unregistered top-level domains.

References & External Analysis

• Malpedia (Fraunhofer FKIE) - Pykspa Details
• Akamai Threat Research - Analysis of DGA Botnet Query Spikes
• NIST National Vulnerability Database - CVE-2010-2568
• Search "pykspa" on VirusTotal (External Analysis)
• Search "pykspa" on Any.Run (Sandbox Sandbox)
• Search "pykspa" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Worm)

Explore other documented threats in the same operational category:

• Beebone
• Pluto
• Vobfus
• Chir
• Cambot
• Netsky
• Lolbot
• Blaster

Machine-readable

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