WannaCry Payload Masquerading As Tasksche Executable For Stealth


Zero‑Dwell Threat Intelligence Report

A narrative, executive‑ready view into the malware’s behavior, exposure, and reliable defenses.
Generated: 2025-12-04 08:31:28 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
5sfxv.exe
Type
Win32 Executable (generic)
SHA‑1
bd327a1bdd3cb79be3477230310de87bb355cbed
MD5
9e520e8a222c1cb66a7d944c26c0b6c1
First Seen
2025-12-01 14:09:02.985644
Last Analysis
2025-12-01 21:28:47.707271
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
2025-11-12 14:47:56 UTC First VirusTotal submission
2025-12-03 21:12:03 UTC Latest analysis snapshot 21 days, 6 hours, 24 minutes
2025-12-04 08:31:28 UTC Report generation time 21 days, 17 hours, 43 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: 65. Detected as malicious: 54. Missed: 11. Coverage: 83.1%.

Detected Vendors

  • Xcitium
  • +53 additional vendors (names not provided)

List includes Xcitium plus an additional 53 vendors per the provided summary.

Missed Vendors

  • Acronis
  • APEX
  • Baidu
  • CMC
  • MaxSecure
  • SentinelOne
  • SUPERAntiSpyware
  • tehtris
  • VIPRE
  • Yandex
  • 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

  • T1027 – encrypt data using AES
  • T1027 – reference AES constants
  • T1129 – parse PE header
  • T1027 – encode data using XOR
  • T1027 – encrypt data using RC4 KSA
  • 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.

Contacted Domains

Domain IP Country ASN/Org
www.msftncsi.com 23.200.3.71 United States Akamai 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
5isohu.com A
www.msftncsi.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
5355 5 udp
53 4 udp
3702 1 udp

UDP Packets

Source IP Dest IP Sport Dport Time Proto
192.168.56.13 192.168.56.255 137 137 3.459313154220581 udp
192.168.56.13 224.0.0.252 49311 5355 5.955093145370483 udp
192.168.56.13 224.0.0.252 55150 5355 3.3857200145721436 udp
192.168.56.13 224.0.0.252 60010 5355 5.396572113037109 udp
192.168.56.13 224.0.0.252 62406 5355 3.3889591693878174 udp
192.168.56.13 224.0.0.252 63527 5355 4.412651062011719 udp
192.168.56.13 239.255.255.250 52252 3702 3.401905059814453 udp
192.168.56.13 8.8.4.4 54879 53 8.003140211105347 udp
192.168.56.13 8.8.4.4 54881 53 7.101954221725464 udp
192.168.56.13 8.8.8.8 54879 53 9.003364086151123 udp
192.168.56.13 8.8.8.8 54881 53 8.096906185150146 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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