Medium-Severity Ryuk Infection Using Delphi-Built Dropper and Overlay Payloads


Zero‑Dwell Threat Intelligence Report

A narrative, executive‑ready view into the malware’s behavior, exposure, and reliable defenses.
Generated: 2025-11-13 21:19:03 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
c9miob8s.exe
Type
PE32 executable (GUI) Intel 80386, for MS Windows
SHA‑1
bcf0fa474d0606dd63d00ba7f1ee856b02513bee
MD5
c3f4a8388035bc4e3aa772af2380cc45
First Seen
2025-10-05 13:28:26.964978
Last Analysis
2025-10-06 12:55:10.364452
Dwell Time
0 days, 7 hours, 33 minutes

Extended Dwell Time Impact

For 23+ 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
2025-09-21 22:01:49 UTC First VirusTotal submission
2025-10-08 14:11:56 UTC Latest analysis snapshot 16 days, 16 hours, 10 minutes
2025-11-13 21:19:03 UTC Report generation time 44 days, 9 hours, 17 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

  • CMC
  • google_safebrowsing
  • MaxSecure
  • SUPERAntiSpyware
  • ViRobot
  • Webroot
  • 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.

Behavioral Storyline — How the Malware Operates

Intensive file system activity (52.59% of behavior) indicates data harvesting, file encryption, or dropper behavior. The threat is actively searching for and manipulating files across the system.

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
File System 17074 52.59%
Registry 6849 21.10%
System 5268 16.23%
Process 1908 5.88%
Misc 443 1.36%
Threading 264 0.81%
Synchronization 193 0.59%
Windows 172 0.53%
Com 166 0.51%
Device 127 0.39%
Services 2 0.01%

MITRE ATT&CK Mapping

  • T1115 – open clipboard
  • T1222 – set file attributes
  • T1082 – get system information on Windows
  • T1614.001 – get keyboard layout
  • T1547.001 – get startup folder
  • T1529 – shutdown system
  • T1082 – get number of processors
  • T1497.001 – reference anti-VM strings targeting VMWare
  • T1082 – get disk size
  • T1010 – find graphical window
  • T1113 – capture screenshot
  • T1614 – get geographical location
  • T1083 – get file version info
  • T1547.004 – persist via Winlogon Helper DLL registry key
  • T1129 – link many functions at runtime
  • T1083 – get common file path
  • T1056.001 – log keystrokes
  • T1027 – encode data using XOR
  • T1082 – get disk information
  • T1027.002 – packed with ASPack
  • T1564.003 – hide graphical window
  • T1059 – accept command line arguments
  • T1082 – check OS version
  • T1010 – enumerate gui resources
  • T1056.001 – log keystrokes via polling
  • T1115 – read clipboard data
  • T1027.005 – contain obfuscated stackstrings
  • T1129 – link function at runtime on Windows
  • T1012 – query or enumerate registry value
  • T1547.001 – reference startup folder

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 2.18.67.72 Europe Akamai Technologies
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
5isohu.com A
www.msftncsi.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
5355 5 udp
53 30 udp
3702 1 udp

UDP Packets

Source IP Dest IP Sport Dport Time Proto
192.168.56.13 192.168.56.255 137 137 3.261482000350952 udp
192.168.56.13 224.0.0.252 49311 5355 5.7752439975738525 udp
192.168.56.13 224.0.0.252 55150 5355 3.1742019653320312 udp
192.168.56.13 224.0.0.252 60010 5355 5.183233022689819 udp
192.168.56.13 224.0.0.252 62406 5355 3.183189868927002 udp
192.168.56.13 224.0.0.252 63527 5355 4.878115892410278 udp
192.168.56.13 239.255.255.250 52252 3702 3.1895010471343994 udp
192.168.56.13 8.8.4.4 50554 53 145.72777795791626 udp
192.168.56.13 8.8.4.4 54879 53 7.743350982666016 udp
192.168.56.13 8.8.4.4 54881 53 7.444953918457031 udp
192.168.56.13 8.8.4.4 55551 53 174.44619703292847 udp
192.168.56.13 8.8.4.4 56197 53 160.0874400138855 udp
192.168.56.13 8.8.4.4 57310 53 66.1025550365448 udp
192.168.56.13 8.8.4.4 57415 53 80.46186804771423 udp
192.168.56.13 8.8.4.4 58697 53 22.805583953857422 udp
192.168.56.13 8.8.4.4 58920 53 98.71224093437195 udp
192.168.56.13 8.8.4.4 60910 53 113.08673906326294 udp
192.168.56.13 8.8.4.4 61004 53 192.70382499694824 udp
192.168.56.13 8.8.4.4 62493 53 51.742913007736206 udp
192.168.56.13 8.8.4.4 62849 53 37.16580295562744 udp
192.168.56.13 8.8.4.4 64533 53 207.05551099777222 udp
192.168.56.13 8.8.4.4 64801 53 127.4776120185852 udp
192.168.56.13 8.8.8.8 50554 53 144.72841787338257 udp
192.168.56.13 8.8.8.8 54879 53 8.743237018585205 udp
192.168.56.13 8.8.8.8 54881 53 8.430770874023438 udp
192.168.56.13 8.8.8.8 55551 53 173.44938707351685 udp
192.168.56.13 8.8.8.8 56197 53 159.08712601661682 udp
192.168.56.13 8.8.8.8 57310 53 65.10283589363098 udp
192.168.56.13 8.8.8.8 57415 53 79.46230697631836 udp
192.168.56.13 8.8.8.8 58697 53 21.80644989013672 udp
192.168.56.13 8.8.8.8 58920 53 97.71348786354065 udp
192.168.56.13 8.8.8.8 60910 53 112.1016800403595 udp
192.168.56.13 8.8.8.8 61004 53 191.6988320350647 udp
192.168.56.13 8.8.8.8 62493 53 50.743820905685425 udp
192.168.56.13 8.8.8.8 62849 53 36.16728591918945 udp
192.168.56.13 8.8.8.8 64533 53 206.0562698841095 udp
192.168.56.13 8.8.8.8 64801 53 126.4787049293518 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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