Malicious .NET Executable Exhibiting WannaCry-Themed Ransomware Traits


Zero‑Dwell Threat Intelligence Report

A narrative, executive‑ready view into the malware’s behavior, exposure, and reliable defenses.
Generated: 2025-12-04 08:22:58 UTC

Executive Overview — What We’re Dealing With

This specimen has persisted long enough to matter. Human experts classified it as Malware, and the telemetry confirms a capable, evasive Trojan with real impact potential.

File
2025-11-16_b984a3fe2735852bb3d6bf3c9695f21c_elex_wannacry_xworm
Type
Generic CIL Executable (.NET, Mono, etc.)
SHA‑1
5d216b72cc3728e9dabc4f9e0f99b837268e4a9b
MD5
b984a3fe2735852bb3d6bf3c9695f21c
First Seen
2025-12-01 14:07:47.891915
Last Analysis
2025-12-02 10:08:42.211980
Dwell Time
0 days, 7 hours, 33 minutes

Extended Dwell Time Impact

For 20+ hours, this malware remained undetected — a half-day window that permitted the adversary to complete initial execution, establish basic persistence, and perform initial system enumeration.

Comparative Context

Industry studies report a median dwell time closer to 21–24 days. This case represents rapid detection and containment within hours rather than days.

Timeline

Time (UTC) Event Elapsed
2025-11-14 20:27:03 UTC First VirusTotal submission
2025-12-03 21:12:59 UTC Latest analysis snapshot 19 days, 0 hours, 45 minutes
2025-12-04 08:22:58 UTC Report generation time 19 days, 11 hours, 55 minutes

Why It Matters

Every additional day of dwell time is not just an abstract number — it is attacker opportunity. Each day equates to more time for lateral movement, stealth persistence, and intelligence gathering.

Global Detection Posture — Who Caught It, Who Missed It

VirusTotal engines: 67. Detected as malicious: 29. Missed: 38. Coverage: 43.3%.

Detected Vendors

  • Xcitium
  • +28 additional vendors (names not provided)

List includes Xcitium plus an additional 28 vendors per the provided summary.

Missed Vendors

  • Acronis
  • AhnLab-V3
  • Alibaba
  • ALYac
  • Antiy-AVL
  • Arcabit
  • Avira
  • Baidu
  • BitDefender
  • CMC
  • Emsisoft
  • ESET-NOD32
  • F-Secure
  • Fortinet
  • google_safebrowsing
  • Gridinsoft
  • Jiangmin
  • K7AntiVirus
  • K7GW
  • Kaspersky
  • Kingsoft
  • MicroWorld-eScan
  • NANO-Antivirus
  • Panda
  • SUPERAntiSpyware
  • TACHYON
  • tehtris
  • TrendMicro
  • TrendMicro-HouseCall
  • VBA32
  • VIPRE
  • VirIT
  • ViRobot
  • Webroot
  • Yandex
  • Zillya
  • ZoneAlarm
  • Zoner

Why it matters: if any endpoint relies solely on a missed engine, this malware can operate with zero alerts. Prevention‑first controls close that gap regardless of signature lag.

MITRE ATT&CK Mapping

  • T1071 – The PE file contains an overlay
  • T1027 – The binary likely contains encrypted or compressed data
  • T1027.002 – The binary likely contains encrypted or compressed data

Following the Trail — Network & DNS Activity

Outbound activity leans on reputable infrastructure (e.g., CDNs, cloud endpoints) to blend in. TLS sessions and
HTTP calls show routine beaconing and IP‑lookup behavior that can masquerade as normal browsing.

Hunting tip: alert on unknown binaries initiating TLS to IP‑lookup services or unusual CDN endpoints — especially early in execution.

What To Do Now — Practical Defense Playbook

  • Contain unknowns: block first‑run binaries by default — signatures catch up, containment works now.
  • EDR controls: alert on keyboard hooks, screen capture APIs, VM/sandbox checks, and command‑shell launches.
  • Registry watch: flag queries/sets under policy paths (e.g., …\FipsAlgorithmPolicy\*).
  • Network rules: inspect outbound TLS to IP‑lookup services and unexpected CDN endpoints.
  • Hunt broadly: sweep endpoints for the indicators above and quarantine positives immediately.

Dwell time equals attacker opportunity. Reducing execution privileges and egress shrinks that window even when vendors disagree.

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