Shellcode Executed via Custom Loader Component by Lynx Ransomware


Zero‑Dwell Threat Intelligence Report

A narrative, executive‑ready view into the malware’s behavior, exposure, and reliable defenses.
Generated: 2026-01-09 15:11:26 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
c4xfzub.exe
Type
Win64 Executable (generic)
SHA‑1
90c072b9d286be8bb253eea6856b38fc9aa8c77b
MD5
983d64677241d705d6a4475bb0e1be22
First Seen
2026-01-08 13:02:38.552818
Last Analysis
2026-01-08 13:06:37.874033
Dwell Time
0 days, 7 hours, 33 minutes

Extended Dwell Time Impact

For 3+ 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
2025-12-27 17:13:01 UTC First VirusTotal submission
2026-01-09 14:20:22 UTC Latest analysis snapshot 12 days, 21 hours, 7 minutes
2026-01-09 15:11:26 UTC Report generation time 12 days, 21 hours, 58 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: 50. Missed: 22. Coverage: 69.4%.

Detected Vendors

  • Xcitium
  • +49 additional vendors (names not provided)

List includes Xcitium plus an additional 49 vendors per the provided summary.

Missed Vendors

  • Acronis
  • AhnLab-V3
  • Antiy-AVL
  • Baidu
  • CMC
  • google_safebrowsing
  • huorong
  • Jiangmin
  • Kaspersky
  • Kingsoft
  • Panda
  • SUPERAntiSpyware
  • TACHYON
  • tehtris
  • Trapmine
  • TrendMicro
  • VirIT
  • 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

  • T1129 – link function at runtime on Windows
  • T1129 – parse PE header
  • T1083 – get file size

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 23.44.129.57 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
www.msftncsi.com A
5isohu.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
192.168.56.11 192.168.56.255 137 137 3.241029977798462 udp
192.168.56.11 224.0.0.252 49563 5355 3.1761679649353027 udp
192.168.56.11 224.0.0.252 54650 5355 3.185724973678589 udp
192.168.56.11 224.0.0.252 55601 5355 4.728033065795898 udp
192.168.56.11 224.0.0.252 60205 5355 3.2222189903259277 udp
192.168.56.11 224.0.0.252 62798 5355 5.7478790283203125 udp
192.168.56.11 239.255.255.250 62184 3702 3.2252559661865234 udp
192.168.56.11 8.8.4.4 51690 53 7.301781177520752 udp
192.168.56.11 8.8.4.4 51899 53 5.77257513999939 udp
192.168.56.11 8.8.8.8 51690 53 8.288195133209229 udp
192.168.56.11 8.8.8.8 51899 53 6.772080183029175 udp

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

Persistence & Policy — Registry and Services

Registry and service telemetry points to policy awareness and environment reconnaissance rather than noisy persistence. Below is a compact view of the most relevant keys and handles; expand to see the full lists where available.

Registry Opened

8

Registry Set

0

Services Started

0

Services Opened

0

Registry Opened (Top 25)

Key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Segment Heap
HKEY_LOCAL_MACHINE\OSDATA\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\SdbUpdates
HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\Safer\CodeIdentifiers
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\SdbUpdates\ManifestedMergeStubSdbs
Show all (8 total)

Registry Set (Top 25)

Services Started (Top 15)

Services Opened (Top 15)

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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