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Echo Response - Week 8 Last Ascent

Echo Response - Week 8 Last Ascent#

Quick Navigation#


README#

Week 8 - Last Ascent#

Challenge Overview#

Challenge Name: Last Ascent
Category: ICS/SCADA Forensics, Incident Response, Privilege Escalation
Difficulty: Insane
Status: COMPLETED


Scenario#

At the culmination of the Proving Grounds: The Gauntlet event, we face the Last Ascent - a critical incident response scenario targeting Megacorp One’s Energy Systems Division. Autonomous wind turbines have been manipulated and taken out of MegaCorp One’s control.

The power stabilization layer has been compromised, and the Codex Circuit’s protective perimeter is now vulnerable. The threat actor has achieved the unthinkable - complete control over critical infrastructure through a sophisticated multi-stage attack.


Challenge Questions#

Q1: Powergrid Shutdown Analysis#

Question: Identify how the Powergrid was shut down. State the technical status of the turbines after the attack (flags, control bits, output states) and provide the IP address of the system from which the attack was performed.

Answer:

  • Turbine Status: Turbines forced into STOP state, run=0, speed register=0, lockout bit=1
  • Attacker IP: 192.168.1.253

Q2: Attacker Knowledge Source#

Question: From where did the attacker gain the knowledge necessary to perform this attack? If from a file, include the complete filename and its SHA-256 hash. If from a website, provide the full URL beginning with “https://”.

Answer:

  • File: WT-PLC_Turbine_Control_Manual.pdf
  • SHA-256: 635598615d4a9823b36163796fdc3c45702280097bad8df23fc1b8c39c9d7101

Q3: RESOURCES Machine Compromise#

Question: How was the attacker able to compromise the RESOURCES machine? Provide the name of the exploited program and the SHA-256 hash of the malicious file used in the compromise.

Answer:

  • Exploited Program: MonitorTool.exe
  • Malicious File SHA-256: E6E4D51009F5EFE2FA1FA112C3FDEEA381AB06C4609945B056763B401C4F3333

Q4: Pivot Information#

Question: What two pieces of information did the attacker obtain on the RESOURCES system that enabled them to pivot to the next system in the attack path?

Answer:

  • SSH Username: vyos
  • SSH Private Key: router2.privkey (for host 192.168.1.253)

Q5: Credential Harvesting#

Question: Enter the username and password of the user that performed the attack in question 3, and the SHA-256 hash of the program responsible for capturing or collecting these login credentials.

Answer:

  • Username: carmen.santos (or MEGACORPONE\carmen.santos)
  • Password: Qwerty09!
  • Program: ssp.dll (Security Support Provider)
  • SHA-256: 566DEE9A89CE772E640CDB1126480F83EE048CEA4B7661A9427AF42A9FAB8B46

Q6: Initial Access Vector#

Question: Identify and analyze the initial access vector. Provide the domain (without suffixes or prefixes) where the payload for initial access was loaded from and the program (including its version) that was exploited or targeted.

Answer:

  • Domain: microsoft-login (full domain: microsoft-login.com)
  • Exploited Program: Chrome version 137.0.7151.56

Q7: Privilege Escalation#

Question: How did the attacker elevate their privileges on CLIENT8? Provide the name and SHA-256 hash of the program responsible for privilege escalation, and the CVE related to the vulnerability used.

Answer:

  • Program: BitLockerDeviceEncrypton.exe (note the typo - masquerading technique!)
  • SHA-256: 20DA751A1B158693C04A392FD499898B055E059EC273841E5026C15E691B6AEA
  • CVE: CVE-2024-35250

Complete Attack Chain#

Phishing (microsoft-login.com)
Initial Access (Chrome 137.0.7151.56)
Privilege Escalation (CVE-2024-35250)
BitLockerDeviceEncrypton.exe ks.sys/MSKSSRV
Credential Harvesting (ssp.dll LSASS)
Captured: carmen.santos:Qwerty09!
Lateral Movement (SSH via router2.privkey)
CLIENT8 Router2 (192.168.1.253)
SCADA Compromise (MonitorTool.exe exploit)
Access to RESOURCES server
ICS Manipulation (Modbus commands)
PLCs forced into 24-hour lockout
TURBINES SHUTDOWN

Key Skills Demonstrated#

  • ICS/SCADA Forensics - Modbus protocol analysis, PLC manipulation detection
  • Windows Forensics - Sysmon log analysis, registry examination
  • Privilege Escalation Analysis - CVE-2024-35250 kernel exploitation
  • Credential Theft Detection - SSP DLL injection into LSASS
  • Browser Forensics - Chrome history and artifact analysis
  • Network Forensics - SSH pivot detection, Modbus traffic analysis
  • Binary Analysis - Masquerading technique detection
  • MITRE ATT&CK Mapping - Comprehensive technique identification

Files#

FileDescription
INVESTIGATION_REPORT.mdComplete forensic investigation report
README.mdThis file - challenge overview

Key Findings#

Novel Techniques Discovered#

  • Typo-squatting in filenames - BitLockerDeviceEncrypton.exe (missing ‘i’)
  • CVE-2024-35250 - Kernel Streaming driver vulnerability exploitation
  • SSP credential harvesting - Malicious DLL injection into LSASS
  • IT-OT pivot attack - From workstation to SCADA through SSH
  • Modbus protocol abuse - Triggering protective lockout intentionally

Indicators of Compromise (IOCs)#

TypeValue
Malicious Domainmicrosoft-login.com
CVECVE-2024-35250
Attacker IP192.168.1.253
ssp.dll Hash566DEE9A89CE772E640CDB1126480F83EE048CEA4B7661A9427AF42A9FAB8B46
Exploit Hash20DA751A1B158693C04A392FD499898B055E059EC273841E5026C15E691B6AEA

References#


Challenge Completed: November 26, 2025
Investigator: MR. Umair


Echo Response - Week 8 Last Ascent
https://ctf-writeups-webb.vercel.app/posts/events-season1-week8-last-ascent/
Author
Umair Aziz
Published at
2026-04-02
License
CC BY-NC-SA 4.0