High-Confidence Lynx Ransomware Sample Detected Across Multiple Vendors


Zero‑Dwell Threat Intelligence Report

A narrative, executive‑ready view into the malware’s behavior, exposure, and reliable defenses.
Generated: 2026-01-09 15:08:25 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
f2spvsh.exe
Type
Generic CIL Executable (.NET, Mono, etc.)
SHA‑1
4a7a7d594689dad7b38ce0b83272c90d66394995
MD5
f6328c2ac8921a9a3d30f7bed1fb88bf
First Seen
2026-01-08 13:01:39.085500
Last Analysis
2026-01-08 13:06:37.405004
Dwell Time
0 days, 7 hours, 33 minutes

Extended Dwell Time Impact

For 4+ minutes, this malware was rapidly detected — demonstrating excellent security controls that intercepted the threat during initial execution phases, severely limiting adversary capabilities.

Comparative Context

Industry studies report a median dwell time closer to 21–24 days. This case represents extremely rapid detection within minutes.

Timeline

Time (UTC) Event Elapsed
2025-12-09 21:50:18 UTC First VirusTotal submission
2026-01-09 14:19:02 UTC Latest analysis snapshot 30 days, 16 hours, 28 minutes
2026-01-09 15:08:25 UTC Report generation time 30 days, 17 hours, 18 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: 53. Missed: 19. Coverage: 73.6%.

Detected Vendors

  • Xcitium
  • +52 additional vendors (names not provided)

List includes Xcitium plus an additional 52 vendors per the provided summary.

Missed Vendors

  • Acronis
  • Antiy-AVL
  • Baidu
  • CAT-QuickHeal
  • CMC
  • Cynet
  • DrWeb
  • google_safebrowsing
  • Gridinsoft
  • Jiangmin
  • Skyhigh
  • SUPERAntiSpyware
  • TACHYON
  • tehtris
  • TrendMicro
  • Webroot
  • Yandex
  • 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

  • T1083 – check if file exists
  • T1027 – obfuscated with Dotfuscator
  • T1070.004 – self delete
  • T1027 – obfuscated with Yano
  • T1140 – decode data using Base64 in .NET
  • T1057 – find process by name
  • T1083 – get common file path
  • T1620 – load .NET assembly
  • T1027 – obfuscated with SmartAssembly
  • T1129 – link function at runtime on Windows
  • T1497.001 – reference anti-VM strings targeting Xen

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.

Observed IPs

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

DNS Queries

Request Type
5isohu.com A

Contacted IPs

IP Country ASN/Org
224.0.0.252
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 4 udp
53 2 udp

UDP Packets

Source IP Dest IP Sport Dport Time Proto
192.168.56.14 192.168.56.255 137 137 3.0808889865875244 udp
192.168.56.14 224.0.0.252 51209 5355 3.041736125946045 udp
192.168.56.14 224.0.0.252 53401 5355 4.212809085845947 udp
192.168.56.14 224.0.0.252 55094 5355 5.610068082809448 udp
192.168.56.14 224.0.0.252 55848 5355 3.050938129425049 udp
192.168.56.14 8.8.4.4 52815 53 6.92547607421875 udp
192.168.56.14 8.8.8.8 52815 53 7.922399044036865 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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