Ramnit

Overview

Ramnit (also known as Nimnul or Cosmu) is a devastating, multi-faceted banking trojan and worm that first emerged in 2010. Originally conceived as a Windows file infector that appended malicious code to executable (EXE, DLL, SCR) and HTML files, its operators subsequently integrated Zeus banking trojan components, transforming it into an aggressive financial fraud engine capable of man-in-the-browser (MitB) attacks. Ramnit is characterized by its aggressive self-propagating worm mechanisms: it spreads across local area networks, infects removable USB storage drives by exploiting Windows Shell shortcut vulnerabilities (CVE-2010-2568), and injects malicious script hooks into stored HTML files. For command and control, Ramnit utilizes a Domain Generation Algorithm (DGA) capable of generating hundreds of candidate domains per day to bypass static firewall blocks. In February 2015, Europol's European Cybercrime Centre (EC3), in collaboration with the FBI, the UK National Crime Agency (NCA), and Germany's BKA, executed an international disruption operation that seized 300 C2 domain names, liberating an estimated 3.2 million compromised computers from the botnet's control.

Known aliases

Threat reports may refer to this family under multiple names:

• Ramnit
• Nimnul
• Cosmu

Threat Actor Attribution

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

• Ramnit Cybercrime Syndicate High confidence
  Basis: Dismantled in February 2015 via a major multinational law enforcement operation led by Europol EC3, the FBI, the UK National Crime Agency (NCA), and German BKA, which seized 300 C2 domain names controlling an estimated 3.2 million infected computers worldwide. [source]

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: Zbot

Known Derivatives & Downstream Variants: Ramnit V1 · Ramnit V2 · Blackhole_Integration

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-2010-2568 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2014-1761 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2013-2551 — 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

• Detect and block DGA-generated domain queries characteristic of Ramnit domain seeds
• Inspect HTTP/HTTPS traffic for known webinject patterns targeting online banking URLs
• Monitor removable storage activity for suspicious .lnk shortcut creation exploiting CVE-2010-2568

Sources: Europol Ramnit Takedown Announcement, CISA Alert TA15-058A

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.

• 7b11545efec11e4f454a88f5d083bc3df426c117dcf46820c78a087e59b21a8a
• d69455325ff2e81177651a02796245d8b8e0b65672d5c314a5116752762a3449

Delivery vectors

• Drive-by download compromises via exploit kits (Angler, Blackhole)
• USB worm propagation using weaponized .lnk shortcut files

Persistence mechanisms

• AppInit_DLLs or Winlogon Userinit registry tampering
• Infection of local EXE and HTML files on all mounted storage volumes

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_RAMNIT_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Ramnit"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "ramnit" ascii wide nocase
        $s2 = "ramnit" ascii wide nocase
        $s3 = "nimnul" ascii wide nocase
        $s4 = "cosmu" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Ramnit (Worm Banker) Execution & Triage
id: fd5cbcc7-87e9-5c0f-92d9-8d1280766908
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Ramnit 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/ramnit
- 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-banker
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1091
- attack.t1547_001
- attack.t1185
- attack.t1055
- attack.t1566_002
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_RAMNIT_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Ramnit 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 = "ramnit" 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 from the corporate network to prevent Ramnit from executing real-time Automated Transfer System (ATS) fraudulent transactions or web injections.
2. Revoke all active online banking sessions, treasury management credentials, and accounting administrator sessions accessed from the machine.
3. Analyze browser process memory (hooks on wininet.dll, ws2_32.dll, nspr4.dll) to detect and eradicate injected Ramnit fraud modules.
4. Notify internal financial compliance and partner banking institutions to place temporary fraud holds or elevated monitoring on relevant accounts.

What to Avoid

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

1. Do not permit financial transactions or banking portal access from any machine in the same broadcast domain until Ramnit network activity is cleared.
2. Avoid relying solely on antivirus scans, as banking trojans frequently hook browser API calls directly in user-mode memory.

References & External Analysis

• Malwarebytes: Worm.Ramnit
• CISA Advisory: CISA Alert TA15-058A (Ramnit Malware Takedown)
• Search "ramnit" on VirusTotal (External Analysis)
• Search "ramnit" on Any.Run (Sandbox Sandbox)
• Search "ramnit" 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 TA15-058A (Ramnit Malware Takedown) ↗

Frequently Asked Questions

Related Threats (Category: Banking Trojan)

Explore other documented threats in the same operational category:

• Carbanak
• Shiotob
• Blackmoon
• Guildma
• Tinynuke
• Sinowal
• Trickster
• Bancos

Machine-readable

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