Simda

Overview

Simda is a versatile, highly evasive modular botnet and credential-theft trojan first detected in 2009. Engineered with aggressive anti-analysis routines, sandbox-detection algorithms, and server-side polymorphism, Simda was operated as a commercial pay-per-install (PPI) infrastructure, renting out compromised computers to secondary cybercriminals to distribute banking trojans, cryptocurrency miners, and search-hijacking adware. At its peak, the Simda botnet enslaved an estimated 770,000 computers worldwide. In April 2015, the INTERPOL Global Complex for Innovation (IGCI) in Singapore coordinated 'Operation Simda'—a landmark international law enforcement strike in conjunction with the FBI, the Dutch National High Tech Crime Unit (NHTCU), the Police Grand-Ducale of Luxembourg, Russian Ministry of Internal Affairs (Department 'K'), Microsoft's Digital Crimes Unit, Kaspersky Lab, and Trend Micro. The operation seized 14 central command servers across the Netherlands, the United States, Luxembourg, Russia, and Poland, severing the operators' control and effectively dismantling the botnet. Kaspersky subsequently deployed a public IP-lookup portal allowing victims worldwide to check for infections.

Known aliases

Threat reports may refer to this family under multiple names:

• Simda
• Win32/Simda
• Trojan.Simda
• Backdoor.Simda

Threat Actor Attribution

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

• Simda Cybercrime Syndicate / INTERPOL Operation Simda Coalition High confidence
  Basis: In April 2015, INTERPOL, the FBI, Dutch Police, and Russian authorities executed Operation Simda, seizing 14 central command servers across 5 nations to dismantle the 770,000-host botnet. [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: Simda.A (2009) · Simda.B · Simda.C (Server-Side Polymorphism) · Simda Ppi Loader

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):

Exploited Vulnerabilities (CVEs)

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

• CVE-2012-1889 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2013-0074 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2015-0071 — 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.

• 4a242f36f6d895f462ebc8375e87a26f8303f26cfb16954316d2ca0190abf0c1
• e236526eb8fb386f6f1c4e97669e4f5530ecdfce9a2ffb38ab8fa176df2c75a4

Delivery vectors

• Drive-by downloads from compromised websites hosting exploit kits targeting browser and Silverlight vulnerabilities (CVE-2013-0074)
• Malvertising campaigns redirecting traffic through stealthy iframe chains

Persistence mechanisms

• Modifies Windows hosts file to block antivirus signature updates
• Registry Run keys and scheduled tasks executing injected DLLs in %APPDATA%

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_SIMDA_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Simda"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "simda" ascii wide nocase
        $s2 = "simda" ascii wide nocase
        $s3 = "win32/simda" ascii wide nocase
        $s4 = "trojan.simda" ascii wide nocase
        $s5 = "backdoor.simda" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Simda (Botnet) Execution & Triage
id: 6331d332-02bb-5b56-93fb-b93d50493837
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Simda 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/simda
- 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.t1055
- attack.t1056_001
- attack.t1562_001
- attack.t1071_001
- attack.t1568_002
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_SIMDA_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Simda 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 = "simda" 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. Isolate the endpoint immediately; Simda acts as a loader, and secondary payloads (like banking trojans) are highly likely to be active.
2. Manually inspect and clean the `%SystemRoot%\System32\drivers\etc\hosts` file, removing any unauthorized entries.
3. Use a specialized, enterprise-grade rootkit removal tool or EDR to locate and terminate the hidden Simda services, as standard antivirus may fail to see them.
4. Given the rootkit capabilities and the likelihood of secondary payload deployment, a complete rebuild of the operating system is highly recommended.

What to Avoid

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

1. Do not rely solely on automated remediation to fix the `hosts` file; verify the cleanup manually to ensure web traffic is no longer being intercepted.
2. Avoid closing the incident after removing the initial Simda dropper; you must investigate what secondary payloads it may have downloaded.

References & External Analysis

• INTERPOL Press Release - Global Operation Takes Down Simda Botnet
• FBI National Press Release - Simda Botnet Disruption
• MITRE ATT&CK - Simda
• Search "simda" on VirusTotal (External Analysis)
• Search "simda" on Any.Run (Sandbox Sandbox)
• Search "simda" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Botnet)

Explore other documented threats in the same operational category:

• Storm
• Phorpiex
• Cybernetic
• Mirai
• Dorkbot
• Glupteba
• Stantinko
• Palevo

Machine-readable

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