Sivis

Overview

Sivis (known across antivirus vendors as Win32.Sivis or W32/Sivis) is a classic Windows PE file infector that first surfaced around 2006. Engineered during the peak era of Windows XP network worms, Sivis systematically searches all local fixed disks, mounted network volumes, and removable storage media for 32-bit executable files (.exe), modifying their header structures to prepend or append malicious viral code. Upon initial execution, Sivis attempts to neutralize defensive software: it terminates active antivirus and firewall processes, deletes security registry keys, and alters system policies to disable Windows Task Manager (DisableTaskMgr) and Registry Editor (DisableRegistryTools) to prevent administrative remediation. The virus establishes network connections to remote HTTP servers to download rogue software packages and adware while actively scanning internal networks to infect shared executable directories.

Known aliases

Threat reports may refer to this family under multiple names:

• Sivis
• Win32.Sivis
• Virus.Win32.Sivis
• W32/Sivis

Threat Actor Attribution

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

• Early Cybercrime Malware Authors Medium confidence
  Basis: First identified in 2006 as a prolific parasitic file infector targeting Windows PE executables. Engineered to tamper with system security software, terminate antivirus processes, and inject malicious code into local executables across shared storage. [source]

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: Sivis.A · Sivis.B

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

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 ↗).

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.

Network detection ideas

• Alert on rapid bulk modifications to executable (.exe) headers across internal network file shares
• Monitor for termination commands directed at antivirus services (e.g. taskkill /f /im avp.exe)
• Detect unexpected registry modifications disabling Windows Task Manager and Registry Editor

Sources: CISA Advisory AA20-302A, Malpedia Sivis

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.

• 0f93a38ce3722b59b48c4cf667b9370cecb393d987d6eec08fdf569da89178bf
• c687e35b7193dc58f7004f2c918ef929c5cbe83e4a9e25d2c2084c8a82cf61a2

Delivery vectors

• Infected software installers shared on peer-to-peer file-sharing networks
• Removable USB drives spreading between connected systems

Persistence mechanisms

• System-wide parasitic infection of Windows utility binaries
• Registry Run key in HKLM\Software\Microsoft\Windows\CurrentVersion\Run

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_SIVIS_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Sivis"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "sivis" ascii wide nocase
        $s2 = "sivis" ascii wide nocase
        $s3 = "win32.sivis" ascii wide nocase
        $s4 = "virus.win32.sivis" ascii wide nocase
        $s5 = "w32/sivis" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Sivis (File Infector) Execution & Triage
id: a3ab2d5c-8e05-5dbb-9fd4-ee664c7822aa
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Sivis 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/sivis
- 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.file-infector
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1055
- attack.t1106
- attack.t1091
- attack.t1485
- attack.t1140
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_SIVIS_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Sivis 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 = "sivis" 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 sever the endpoint from the network; Sivis will aggressively hunt for and infect executables on shared corporate network drives.
2. Assume all <code>.exe</code> and <code>.scr</code> files on the host are compromised and potentially corrupted beyond repair.
3. Do not attempt to 'clean' the files using standard AV, as this frequently destroys the legitimate application data appended to the virus.
4. Perform a complete bare-metal rebuild of the operating system and restore applications from known-clean, read-only installation media.

What to Avoid

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

1. Avoid backing up executable files from the infected machine; you will only be backing up the polymorphic viral payloads.
2. Do not execute any diagnostic tools directly from the infected host, as they will likely become infected upon execution.

References & External Analysis

• CISA Advisory: CISA Alert AA20-302A (Top Routinely Exploited Vulnerabilities)
• Search "sivis" on VirusTotal (External Analysis)
• Search "sivis" on Any.Run (Sandbox Sandbox)
• Search "sivis" on MalwareBazaar (Malware Samples)

North American Authority Advisory (CISA / NIST)

The Cybersecurity and Infrastructure Security Agency (CISA) has published an official US federal advisory on this family, which can be mapped to NIST Cybersecurity Framework (CSF) incident response controls: CISA Alert AA20-302A (Top Routinely Exploited Vulnerabilities) ↗

Frequently Asked Questions

Related Threats (Category: File Infector)

Explore other documented threats in the same operational category:

• Fujacks
• Pioneer
• Tenga
• Alman
• Invader
• Cyn
• Parite
• Xpaj

Machine-readable

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