Wapomi

Overview

Wapomi (widely documented by antivirus laboratories as Virus.Wapomi or Otwycal) is a parasitic polymorphic PE file infector and worm that first surfaced in 2010. Engineered with advanced polymorphic encryption and opcode substitution engines, Wapomi scans local hard drives, removable USB storage media, and mapped enterprise network shares, prepending or appending its viral code to legitimate 32-bit Portable Executable (.exe) files. Upon execution of an infected host binary, Wapomi's decryptor stub extracts the original executable into memory to ensure uninterrupted user operation while covertly injecting malicious payloads into system processes (such as explorer.exe). The worm acts as a dual-threat mechanism: in addition to self-propagating across network volumes, it establishes an outbound backdoor connection to compromised web servers, downloading secondary cybercrime payloads including banking trojans, infostealers, and click-fraud utilities. To preserve network connectivity, Wapomi automatically adds itself to the Windows Firewall authorized applications list.

Known aliases

Threat reports may refer to this family under multiple names:

• Wapomi
• Virus.Wapomi
• W32.Wapomi
• PE_WAPOMI
• Otwycal

Threat Actor Attribution

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

• Polymorphic Cybercrime Group / Independent Authors Medium confidence
  Basis: Surfaced in 2010 as a parasitic polymorphic PE file infector and network worm. Engineered with complex opcode substitution and garbage instructions, it acts as an infection multiplier by appending code to clean executables while establishing backdoors to download financial malware. [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: Wapomi.A · Wapomi.B · Wapomi.C

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-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.

Network detection ideas

• Detect non-browser Windows system binaries (e.g. explorer.exe) issuing direct HTTP GET requests to download executable binaries
• Alert on bulk file modification events appending code to .exe and .scr files on local and shared storage
• Monitor for unauthorized additions to Windows Firewall allowed program exceptions

Sources: CISA Advisory AA20-302A, Malpedia Wapomi

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.

• a3b95764d7df7f73db17f18b3dcaecdf0e1fe6b77ae4b0d0092cce53df4a6138
• 0a0b9875e6382a17cfc1f44d82ef2b0cbe7a13d31707963d4e0ce1d0449265f2

Delivery vectors

• Removable USB drives spreading via .lnk shortcut exploits and autorun
• Execution of infected host application binaries downloaded from peer-to-peer networks

Persistence mechanisms

• System-wide file infection ensuring execution whenever any infected application is launched
• Registry Run key in HKCU\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_WAPOMI_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Wapomi"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "wapomi" ascii wide nocase
        $s2 = "wapomi" ascii wide nocase
        $s3 = "virus.wapomi" ascii wide nocase
        $s4 = "w32.wapomi" ascii wide nocase
        $s5 = "pe_wapomi" ascii wide nocase
        $s6 = "otwycal" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Wapomi (Worm Banker) Execution & Triage
id: df629dbf-1347-5723-8017-c952b1845a0e
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Wapomi 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/wapomi
- 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.t1055_009
- attack.t1105
- attack.t1027_001
- attack.t1562_004
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_WAPOMI_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Wapomi 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 = "wapomi" 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 Wapomi 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 Wapomi 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 Wapomi 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

• CISA Advisory: CISA Alert AA20-302A (Top Routinely Exploited Vulnerabilities)
• Search "wapomi" on VirusTotal (External Analysis)
• Search "wapomi" on Any.Run (Sandbox Sandbox)
• Search "wapomi" 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: Banking Trojan)

Explore other documented threats in the same operational category:

• Guildma
• Gozi
• Danabot
• Tinba
• Clipbanker
• Shiz
• Bancos
• Snifula

Machine-readable

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