Large WannaCry Variant Triggering Extensive Multi-Engine Detections


Zero‑Dwell Threat Intelligence Report

A narrative, executive‑ready view into the malware’s behavior, exposure, and reliable defenses.
Generated: 2025-12-04 08:28:53 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
21m5kb.exe
Type
Win32 Executable MS Visual C++ (generic)
SHA‑1
a382af5fda696b81b8ce7e23f194737dd53d5f62
MD5
8ae11bdabb3c09eefdb460ce86afd44b
First Seen
2025-12-01 14:07:47.867422
Last Analysis
2025-12-01 21:28:47.266264
Dwell Time
0 days, 7 hours, 33 minutes

Extended Dwell Time Impact

For 7+ hours, this malware remained undetected — a several-hour window that allowed the adversary to complete initial compromise and begin early-stage persistence establishment.

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
2025-11-11 00:32:57 UTC First VirusTotal submission
2025-12-03 21:11:47 UTC Latest analysis snapshot 22 days, 20 hours, 38 minutes
2025-12-04 08:28:53 UTC Report generation time 23 days, 7 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: 72. Detected as malicious: 64. Missed: 8. Coverage: 88.9%.

Detected Vendors

  • Xcitium
  • +63 additional vendors (names not provided)

List includes Xcitium plus an additional 63 vendors per the provided summary.

Missed Vendors

  • Acronis
  • CMC
  • Google
  • google_safebrowsing
  • SUPERAntiSpyware
  • TACHYON
  • tehtris
  • VirIT

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.

Behavioral Storyline — How the Malware Operates

This threat shows heavy registry manipulation (48.93% of total behavior), indicating persistent backdoor installation, configuration tampering, or system policy modification attempts. The malware likely establishes persistence mechanisms and modifies security settings to maintain long-term access.

Behavior Categories (weighted)

Weight values represent the frequency and intensity of malware interactions with specific system components. Higher weights indicate more aggressive targeting of that category. Each operation (registry access, file modification, network connection, etc.) contributes to the category’s total weight, providing a quantitative measure of the malware’s behavioral focus.

Category Weight Percentage
Registry 275 48.93%
System 217 38.61%
Threading 32 5.69%
File System 13 2.31%
Network 9 1.60%
Services 7 1.25%
Process 6 1.07%
Hooking 1 0.18%
Crypto 1 0.18%
Synchronization 1 0.18%

MITRE ATT&CK Mapping

  • T1543.003 – start service
  • T1543.003 – modify service
  • T1569.002 – modify service
  • T1027.005 – contain obfuscated stackstrings
  • T1082 – get number of processors
  • T1129 – link function at runtime on Windows
  • T1016 – get socket status
  • T1543.003 – persist via Windows service
  • T1569.002 – persist via Windows service
  • T1083 – get file size
  • T1543.003 – create service
  • T1569.002 – create service

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.

Contacted Domains

Domain IP Country ASN/Org
www.msftncsi.com 23.200.3.9 United States Akamai Technologies, Inc.
www.aieov.com 13.248.169.48 United States Amazon Technologies Inc.

Observed IPs

IP Country ASN/Org
224.0.0.252
239.255.255.250
8.8.4.4 United States Google LLC
8.8.8.8 United States Google LLC

DNS Queries

Request Type
www.msftncsi.com A
5isohu.com A
www.aieov.com A

Contacted IPs

IP Country ASN/Org
224.0.0.252
239.255.255.250
8.8.4.4 United States Google LLC
8.8.8.8 United States Google LLC

Port Distribution

Port Count Protocols
137 1 udp
138 1 udp
5355 5 udp
53 16 udp
3702 1 udp

UDP Packets

Source IP Dest IP Sport Dport Time Proto
192.168.56.13 192.168.56.255 137 137 3.243760824203491 udp
192.168.56.13 192.168.56.255 138 138 9.257421970367432 udp
192.168.56.13 224.0.0.252 49311 5355 5.732597827911377 udp
192.168.56.13 224.0.0.252 55150 5355 3.171013832092285 udp
192.168.56.13 224.0.0.252 60010 5355 5.181556940078735 udp
192.168.56.13 224.0.0.252 62406 5355 3.1732969284057617 udp
192.168.56.13 224.0.0.252 63527 5355 5.117609024047852 udp
192.168.56.13 239.255.255.250 52252 3702 3.18064284324646 udp
192.168.56.13 8.8.4.4 54879 53 7.793844938278198 udp
192.168.56.13 8.8.4.4 54881 53 7.747525930404663 udp
192.168.56.13 8.8.4.4 57310 53 66.60091590881348 udp
192.168.56.13 8.8.4.4 57415 53 81.02266001701355 udp
192.168.56.13 8.8.4.4 58697 53 23.163968801498413 udp
192.168.56.13 8.8.4.4 58920 53 99.35136699676514 udp
192.168.56.13 8.8.4.4 62493 53 52.22613000869751 udp
192.168.56.13 8.8.4.4 62849 53 37.5700249671936 udp
192.168.56.13 8.8.8.8 54879 53 8.788395881652832 udp
192.168.56.13 8.8.8.8 54881 53 8.742156028747559 udp
192.168.56.13 8.8.8.8 57310 53 65.60104584693909 udp
192.168.56.13 8.8.8.8 57415 53 80.02307391166687 udp
192.168.56.13 8.8.8.8 58697 53 22.16399884223938 udp
192.168.56.13 8.8.8.8 58920 53 98.35130286216736 udp
192.168.56.13 8.8.8.8 62493 53 51.2265408039093 udp
192.168.56.13 8.8.8.8 62849 53 36.57001090049744 udp

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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