Campaign Identifier: Arsenal-237-New-Files-109.230.231.37

Last Updated: January 27, 2026

Report Context: New Files from Arsenal-237 Directory

This report analyzes 11 NEW malware samples recently added to the same open directory (109.230.231.37) that was previously documented in early January 2026. These newly dropped files represent significant evolution of the Arsenal-237 toolkit with advanced capabilities.

Previous Analysis Coverage:

This Report’s Focus:

  • 11 NEW samples added to the directory after initial discovery
  • Advanced capabilities including BYOVD (Bring Your Own Vulnerable Driver), kernel-mode rootkit, and enterprise-grade ransomware
  • Higher sophistication than original samples, indicating toolkit maturation

Note: If you’re looking for the original Arsenal-237 analysis covering the first 16 samples, please refer to the Executive Overview report. This landing page focuses exclusively on the 11 newly discovered files.

BLUF: The Arsenal-237 Threat

The Arsenal-237 toolkit is a highly sophisticated, multi-stage ransomware attack platform, meticulously engineered for enterprise-level compromise. Its modular design, leveraging modern Rust programming, signifies a professional and well-resourced threat actor. The attack sequence typically initiates with lpe.exe, a privilege escalation wrapper that employs five distinct techniques-including token impersonation from critical Windows processes like lsass.exe and winlogon.exe, registry UAC bypass via fodhelper.exe hijacking, and SYSTEM-level scheduled tasks-to achieve NT AUTHORITY\SYSTEM privileges. This elevated access is crucial for the subsequent defense evasion phase.

Following privilege escalation, the toolkit deploys advanced defense evasion modules designed to blind security infrastructure. killer.dll and its specialized variant killer_crowdstrike.dll (which specifically targets CrowdStrike Falcon processes such as CSFalconService.exe and csagent.exe) utilize a “Bring Your Own Vulnerable Driver” (BYOVD) technique. This involves weaponizing the legitimately signed but vulnerable BdApiUtil64.sys (Baidu antivirus driver) or ProcExpDriver.sys (Process Explorer driver) to execute kernel-mode IOCTL commands (e.g., 0x800024B4) that terminate over 20 different security products. The more evolved rootkit.dll expands on this by integrating additional capabilities like Unicode-based file hiding, API hooking for call interception, and PowerShell integration, alongside anti-forensics measures that target analysis tools such as Process Explorer and Wireshark.

Once defenses are neutralized, the toolkit establishes persistence and harvests credentials. nethost.dll serves as a resilient C2 communication module, using hardcoded TCP targets like 8.8.8.8:53 and 127.0.0.1:53, and is capable of PowerShell execution, system enumeration, and data exfiltration via Base64. chromelevator.exe is a specialized tool for systematically extracting credentials (cookies, passwords, payment data) from Chromium-based browsers (Chrome, Brave, Edge) through reflective DLL injection and direct syscalls to bypass EDR. The ultimate goal is ransomware deployment, with variants like new_enc.exe targeting enterprise backup solutions (e.g., Veritas Backup Exec agents and VSS snapshots) and utilizing a hardcoded ChaCha20key. The most dangerous variant, full_test_enc.exe, employs multi-threaded hybrid encryption (RSA-OAEP + ChaCha20) for irreversible data destruction across all accessible drives and network shares, operating entirely offline without C2 dependence. The existence of dec_fixed.exe, a victim-specific decryptor with a unique hardcoded key, strongly confirms an active Ransomware-as-a-Service (RaaS) model with advanced operational maturity and victim support, solidifying Arsenal-237 as a critical and highly effective threat.

The Organizational Threat in Plain Terms

If Arsenal-237 reaches your infrastructure, attackers gain the ability to:

  1. Disable security products using rootkit techniques (malware that hides at the deepest system level, defeating standard antivirus detection)
  2. Escalate privileges to SYSTEM level (gaining complete administrative control)
  3. Establish persistent backdoor access (maintaining control even after system reboots)
  4. Steal encryption keys from web browsers and credential stores
  5. Deploy ransomware that encrypts critical business data with hybrid cryptography (encryption so strong that even expert cryptographers cannot break it without the attacker’s private decryption key)
  6. Negotiate ransom demands with threat actors maintaining per-victim decryption capabilities

The most alarming aspect: Evidence suggests this toolkit is actively under development (test builds recovered), indicating imminent deployment campaigns.

Executive Risk Summary

Risk Factor Score (1-10) Business Impact
Overall Toolkit Risk 9.5/10 CRITICAL - Requires immediate attention from executive leadership
Data Encryption Risk 10/10 All enterprise data at risk; recovery requires external decryption keys
System Compromise 9.5/10 Complete infrastructure control possible; kernel-level persistence
Detection Evasion 9/10 Kernel rootkit defeats most detection systems; backup targeting
Operational Resilience 9/10 Distributed across multiple components; difficult to fully remediate
Ransomware Recovery 8.5/10 Military-grade hybrid encryption; recovery unlikely without attacker’s decryption keys

Overall Risk Assessment: CRITICAL (9.5/10) - Executive escalation and immediate defensive action required.

Confidence Level Framework

  • CONFIRMED: Malware functionality directly observed in static/dynamic analysis
  • HIGHLY LIKELY (90%+): Multiple samples confirm behavior; attacks probable
  • LIKELY (75-90%): Reasonable inference from code and attack patterns
  • POSSIBLE (50-75%): Analytical judgment; requires additional evidence

Quick Reference: New Files Analysis Resources

Arsenal-237 New Files - Recently Added Malware

Each malware sample analyzed in this investigation has three companion resources: a comprehensive technical report with behavioral analysis and incident response guidance, a detection package with YARA/Sigma rules for hunting and prevention, and a machine-readable IOC feed in JSON format for SIEM/EDR ingestion.

killer.dll (BYOVD Process Termination): Technical Report Detection Package IOC Feed
killer_crowdstrike.dll (CrowdStrike Variant): Technical Report Detection Package IOC Feed
lpe.exe (Privilege Escalation): Technical Report Detection Package IOC Feed
BdApiUtil64.sys (Vulnerable Baidu Driver): Technical Report Detection Package IOC Feed
rootkit.dll (Kernel-Mode Rootkit): Technical Report Detection Package IOC Feed
nethost.dll (DLL Hijacking Persistence): Technical Report Detection Package IOC Feed
chromelevator.exe (Browser Credential Theft): Technical Report Detection Package IOC Feed
enc_c2.exe (Rust Ransomware with Tor C2): Technical Report Detection Package IOC Feed
new_enc.exe (Human-Operated Ransomware): Technical Report Detection Package IOC Feed
dec_fixed.exe (Ransomware Decryptor): Technical Report Detection Package IOC Feed
full_test_enc.exe (Advanced Rust Ransomware): Technical Report Detection Package IOC Feed

Quick Reference: Toolkit Component Overview

This landing page serves as the index to 11 detailed analysis reports covering the complete Arsenal-237 attack chain. Each individual component report includes:

  • Complete file hashes (MD5, SHA1, SHA256) and IOC feeds
  • Detection rules and YARA signatures
  • Detailed behavioral analysis and hunting queries
  • MITRE ATT&CK technique mappings

Phase 1: Defense Evasion & Privilege Escalation (5 Components)

These components disable security products and elevate attacker privileges to kernel level.

Phase 2: Persistence & Credential Access (2 Components)

These components maintain access and harvest encryption keys from browsers.

Phase 3: Impact - Ransomware Deployment (4 Components)

These components perform the actual encryption and provide victim-specific decryption capabilities.

Table of Contents

  1. Toolkit Architecture Overview
  2. Component Analysis Index
  3. Attack Chain Integration
  4. Threat Intelligence Summary
  5. Strategic Defensive Recommendations
  6. FAQ - Common Questions
  7. Key Takeaways
  8. Confidence Levels Summary

Toolkit Architecture Overview

Design Philosophy: Professional Ransomware-as-a-Service

The Arsenal-237 toolkit demonstrates characteristics of a mature Ransomware-as-a-Service (RaaS) operation:

  • Modular architecture allowing flexible deployment scenarios
  • Per-victim key management enabling affiliate tracking and decryption licensing
  • Multiple evasion techniques targeting different security products
  • Test/beta variants indicating pre-deployment testing and iteration
  • Rust implementation providing cross-platform capability and advanced language features

Toolkit Structure: Three Operational Phases

PHASE 1: Defense Evasion & Privilege Escalation
+-----------------------------------------------------+
| killer.dll / killer_crowdstrike.dll                 | Terminate security products
| lpe.exe                                             | Escalate to SYSTEM
| BdApiUtil64.sys (vulnerable Baidu driver)           | Acquire kernel access
| rootkit.dll                                         | Hide malware from detection
+-----------------------------------------------------+
                        |
                        v
PHASE 2: Persistence & Credential Access
+-----------------------------------------------------+
| nethost.dll (masquerading .NET loader)              | DLL hijacking persistence
| chromelevator.exe                                   | Browser credential theft
+-----------------------------------------------------+
                        |
                        v
PHASE 3: Impact - Ransomware Deployment
+-----------------------------------------------------+
| enc_c2.exe / new_enc.exe / full_test_enc.exe        | Encrypt critical data
| dec_fixed.exe                                       | Victim-specific decryption
+-----------------------------------------------------+

Key Technical Characteristics

Cryptographic Foundation:

  • RSA-OAEP + ChaCha20 hybrid encryption in advanced variants (impossible to decrypt without private key)
  • Per-victim key architecture enabling RaaS affiliate model
  • Hardcoded keys in test variants revealing operational security weaknesses
  • Different keys across samples suggesting builder/deployment tracking

Evasion Techniques:

  • Kernel-mode rootkit for process/thread/driver hiding
  • BYOVD (Bring Your Own Vulnerable Driver) kernel access
  • Specific CrowdStrike variant indicating EDR product research
  • Anti-VM and anti-analysis detection capabilities

Rust Implementation:

  • Multi-threaded encryption using Rayon library
  • Memory safety and exploitation resilience
  • Cross-platform capability
  • Professional development indicators

Component Analysis Index

All 11 components are documented in individual detailed reports. Click links below to access full technical analysis, IOCs, and detection rules for each component.

PHASE 1: DEFENSE EVASION & PRIVILEGE ESCALATION

1. killer.dll - Basic BYOVD Process Termination

Component Type: Security Product Disabler (BYOVD-based)

Technical Summary:

  • Basic driver-level process termination utility
  • Uses Baidu driver (BdApiUtil64.sys) for kernel access
  • Terminates security product processes
  • Foundation for more sophisticated variants

File Identifiers:

  • MD5: c031054f6140e2c366eaf4263f827dbf
  • SHA256: 10eb1fbb2be3a09eefb3d97112e42bb06cf029e6cac2a9fb891b8b89a25c788d

Confidence Level: CONFIRMED (static and behavioral analysis)

Why This Matters: This component demonstrates the attack chain’s first critical objective: disabling endpoint security. Before encryption begins, threats must eliminate detection capabilities.

Link to Full Report: ./killer-dll.md

2. killer_crowdstrike.dll - CrowdStrike-Specific Process Termination

Component Type: EDR-Specific Defense Disabler

Technical Summary:

  • Variant specifically targeting CrowdStrike Falcon EDR
  • Advanced product knowledge indicating targeted research
  • Kernel-mode termination capability
  • Suggests threat actors prioritize CrowdStrike environments

File Identifiers:

  • MD5: 6926ea1b4c4bff01a23b7e1728583348
  • SHA256: e26e9221f4e9a437716a28c08c5f74c6a2ecae2c47b77091db7d21f36ed2f7d3

Confidence Level: CONFIRMED (product-specific function names and driver interactions)

Why This Matters: The existence of a CrowdStrike-specific variant reveals threat actor knowledge of enterprise security deployments and willingness to customize attack components. This indicates sophisticated operational planning.

Link to Full Report: ./killer_crowdstrike-dll.md

3. lpe.exe - Privilege Escalation Wrapper

Component Type: Privilege Escalation Tool

Technical Summary:

  • Wrapper executable for privilege escalation
  • Elevates command execution to SYSTEM level
  • Required for subsequent kernel-mode operations
  • Critical bridge between user-mode and kernel-mode components

File Identifiers:

  • MD5: 47400a6b7c84847db0513e6dbc04e469
  • SHA256: c4dda7b5c5f6eab49efc86091377ab08275aa951d956a5485665954830d1267e

Confidence Level: CONFIRMED (API calls and capability testing)

Why This Matters: Kernel-mode rootkit and driver operations require SYSTEM-level privileges. This component is essential for the entire attack chain to function. Detection of lpe.exe activity should trigger immediate investigation.

Link to Full Report: ./lpe-exe.md

4. BdApiUtil64.sys - Vulnerable Baidu Driver (BYOVD)

Component Type: Vulnerable Driver for Kernel Access

Technical Summary:

  • Baidu antivirus driver with known privilege escalation vulnerability
  • Exploited for kernel-mode code execution (BYOVD technique)
  • Legitimate driver signature enables Windows acceptance
  • Critical component enabling rootkit deployment

File Identifiers:

  • MD5: ced47b89212f3260ebeb41682a4b95ec
  • SHA256: 47ec51b5f0ede1e70bd66f3f0152f9eb536d534565dbb7fcc3a05f542dbe4428

Confidence Level: CONFIRMED (known CVE and exploitation pattern)

Why This Matters: This represents the “Bring Your Own Vulnerable Driver” technique-using legitimate, signed drivers to bypass kernel protection mechanisms. This technique is increasingly common in sophisticated attacks and extremely difficult to detect.

Link to Full Report: ./BdApiUtil64-sys.md

5. rootkit.dll - Kernel-Mode Rootkit

Component Type: Kernel-Mode Persistence and Hiding

Technical Summary:

  • Kernel-mode rootkit installed via BYOVD exploitation
  • Hides malware processes, threads, and drivers
  • Maintains persistence across reboots
  • Defeats standard user-mode detection techniques
  • Critical evasion component

File Identifiers:

  • MD5: 674795d4d4ec09372904704633ea0d86
  • SHA256: e71240f26af1052172b5864cdddb78fcb990d7a96d53b7d22d19f5dfccdf9012

Confidence Level: CONFIRMED (kernel driver analysis)

Why This Matters: A kernel-mode rootkit fundamentally changes the security posture of an infected system. Standard antivirus and monitoring tools running in user-mode cannot detect hidden processes. This requires specialized kernel-mode detection tools.

Link to Full Report: ./rootkit-dll.md

PHASE 2: PERSISTENCE & CREDENTIAL ACCESS

6. nethost.dll - Masquerading .NET Loader (DLL Hijacking)

Component Type: Persistence Mechanism (DLL Hijacking)

Technical Summary:

  • Masquerades as legitimate .NET runtime component (nethost.dll)
  • Establishes persistence through DLL hijacking
  • Loads malicious code through legitimate .NET processes
  • Survives security scanning and process analysis

File Identifiers:

  • MD5: f91ff1bb5699524524fff0e2587af040
  • SHA256: 158f61b6d10ea2ce78769703a2ffbba9c08f0172e37013de960d9efe5e9fde14

Confidence Level: CONFIRMED (file analysis and hijacking patterns)

Why This Matters: DLL hijacking persistence ensures malware survives remediation attempts and system reboots. By impersonating legitimate system components, this technique evades detection based on file reputation.

Link to Full Report: ./nethost-dll.md

7. chromelevator.exe - Browser Credential Theft

Component Type: Credential Harvesting Tool

Technical Summary:

  • Specialized tool for extracting credentials from Chromium-based browsers
  • Targets Chrome, Edge, Brave, and related browsers
  • Decrypts stored passwords and authentication tokens
  • Enables account takeover and lateral movement
  • Reveals high-value intelligence about victim organization

File Identifiers:

  • MD5: bc376c951eacb36bf0909a43588e6444
  • SHA256: 92c4f4b7748f23d6dcd5af43595f34e4bb8e284a85d2c1647b189c1bb59a784a

Confidence Level: CONFIRMED (static analysis and behavioral observation)

Why This Matters: Browser credentials provide direct access to cloud accounts, SaaS platforms, and critical services. Compromised credentials enable lateral movement without additional exploitation, making this a high-value component in the attack chain.

Link to Full Report: ./chromelevator-exe.md

PHASE 3: IMPACT - RANSOMWARE DEPLOYMENT

8. enc_c2.exe - Rust Ransomware with Tor C2

Component Type: Ransomware Encryptor (Remote-Controlled Variant)

Technical Summary:

  • Rust-based ransomware with remote C2 control
  • Tor-based command and control communication
  • ChaCha20 encryption for file encryption
  • Builder ID tracking for RaaS affiliate tracking
  • Enables real-time operator control during encryption

File Identifiers:

  • MD5: 32a3497e57604e1037f1ff9993a8fdaa
  • SHA256: 613d4d0f1612686742889e834ebc9ebff6ae021cf81a4c50f66369195ca01899

Confidence Level: CONFIRMED (Rust code analysis and C2 communication)

Why This Matters: This variant enables attackers to monitor encryption progress, abort if detected, and coordinate with victims during the ransom negotiation phase. Tor-based C2 defeats network-level blocking attempts.

Link to Full Report: ./enc_c2-exe.md

9. new_enc.exe - Human-Operated Rust Ransomware (v0.5-beta)

Component Type: Advanced Ransomware Encryptor

Technical Summary:

  • Professional Rust ransomware implementation (v0.5-beta designation)
  • Hardcoded ChaCha20 key (67e6096a…)
  • Enterprise backup targeting
  • Beta version indicates pre-deployment testing
  • Per-victim key architecture

File Identifiers:

  • MD5: a16ba61114fa5a40afce54459bbff21e
  • SHA256: 90d223b70448d68f7f48397df6a9e57de3a6b389d5d8dc0896be633ca95720f2

Confidence Level: CONFIRMED (binary analysis confirms hardcoded key and targeting logic)

Operational Security Warning: HIGHLY LIKELY (95%) - Hardcoded key enables decryption without ransom payment, indicating operational security vulnerability in this variant.

Why This Matters: CRITICAL FINDING: The presence of a hardcoded encryption key in this variant suggests either a development/test build or a significant operational security lapse. However, the “v0.5-beta” designation and enterprise backup targeting indicate this is a deliberate development iteration, not a deployment variant.

Link to Full Report: ./new_enc-exe.md

10. dec_fixed.exe - Ransomware Decryptor

Component Type: Victim-Specific Decryption Tool

Technical Summary:

  • Decryption utility for Arsenal-237 ransomware victims
  • Per-victim key architecture CONFIRMED (different key: 1e0d8597…)
  • Enables RaaS affiliate model with victim-specific decryption
  • Indicates operational maturity of threat actors

File Identifiers:

  • MD5: 7c5493a0a5df52682a5c2ba433634601
  • SHA256: d73c4f127c5c0a7f9bf0f398e95dd55c7e8f6f6a5783c8cb314bd99c2d1c9802

Confidence Level: CONFIRMED (key analysis and decryption verification)

Critical Intelligence: HIGHLY LIKELY (95%) - Per-victim key model confirms RaaS operational structure with affiliate-based ransomware distribution.

Why This Matters: The decryptor’s different key from other ransomware variants PROVES that Arsenal-237 uses per-victim key management. This indicates a sophisticated RaaS operation where each victim receives custom encryption keys and corresponding decryption capabilities. This model enables:

  • Affiliate tracking and revenue sharing
  • Victim-specific pricing negotiations
  • Decryption licensing control

Link to Full Report: ./dec_fixed-exe.md

11. full_test_enc.exe - Advanced Rust Ransomware (RSA+ChaCha20)

Component Type: Enterprise-Grade Ransomware Encryptor

Technical Summary:

  • Most sophisticated Arsenal-237 variant recovered
  • Hybrid RSA-OAEP + ChaCha20 encryption (IMPOSSIBLE to decrypt without private key)
  • Multi-threaded encryption using Rayon library
  • Large binary size (15.5 MB) indicating comprehensive functionality
  • Rust implementation with advanced cryptographic libraries
  • Test/beta version designation indicates recent development

File Identifiers:

  • MD5: 1fe8b9a14f9f8435c5fb5156bcbc174e
  • SHA256: 4d1fe7b54a0ce9ce2082c167b662ec138b890e3f305e67bdc13a5e9a24708518
  • Binary Size: 15.5 MB (unusually large, indicating bundled libraries)

Confidence Level: CONFIRMED (cryptographic analysis and hybrid encryption verification)

Decryption Reality: IMPOSSIBLE without access to threat actor’s RSA private key. External decryption services cannot help. Recovery depends entirely on paying ransom or restoring from offline backups.

Why This Matters: CRITICAL: This represents the most dangerous Arsenal-237 variant. The hybrid RSA-OAEP + ChaCha20 encryption creates an asymmetric cryptographic challenge:

  1. RSA-OAEP protects the ChaCha20 symmetric key with threat actor’s public key
  2. Only threat actors with the corresponding private key can decrypt
  3. Brute-force attack is cryptographically infeasible
  4. Recovery without external decryption key is impossible

This is the “point of no return” variant. Organizations hit with this variant face complete data loss unless they have unencrypted offline backups or pay ransom for the decryption key.

Link to Full Report: ./full_test_enc-exe.md

Attack Chain Integration

How Components Work Together: A Complete Attack Scenario

The Arsenal-237 toolkit represents a complete operational workflow from initial compromise to final data encryption:

STAGE 1: Initial Access (Pre-toolkit deployment)

  • Attacker gains initial system access (phishing, RDP, supply chain, etc.)
  • Typically with limited user-level privileges

STAGE 2: Defense Evasion (Phase 1 components)

  1. Deploy lpe.exe -> Escalate to SYSTEM privileges
  2. Load vulnerable BdApiUtil64.sys driver
  3. Use BYOVD exploit to achieve kernel-mode code execution
  4. Inject rootkit.dll into kernel -> Hide malware from detection
  5. Execute killer.dll or killer_crowdstrike.dll -> Disable security products
  6. Security products disabled; attacker now undetectable

STAGE 3: Establish Persistence (Phase 2 components)

  1. Deploy nethost.dll into legitimate Windows processes
  2. Establish persistence through DLL hijacking
  3. Survival across reboots and remediation attempts guaranteed
  4. Execute chromelevator.exe -> Steal browser credentials
  5. Credentials harvested; lateral movement capabilities acquired

STAGE 4: Deploy Ransomware (Phase 3 components)

  1. Activate enc_c2.exe (remote-controlled variant) -> Monitor encryption progress
  2. OR deploy new_enc.exe or full_test_enc.exe -> Begin file encryption
  3. Ransomware encrypts all critical data (documents, databases, backups)
  4. Provide dec_fixed.exe decryptor ONLY after ransom payment
  5. Enterprise unable to recover; business disruption critical

Multi-Phase Attack Characteristics

Phase Objective Components Success Criteria
Phase 1 Establish control, disable defenses killer.dll, lpe.exe, BdApiUtil64.sys, rootkit.dll Security products disabled, malware hidden
Phase 2 Persist and gather intelligence nethost.dll, chromelevator.exe Credentials stolen, persistence established
Phase 3 Execute impact and extort enc_c2.exe, new_enc.exe, full_test_enc.exe, dec_fixed.exe Data encrypted, ransom demand leverage

Operational Maturity Indicators

This toolkit demonstrates characteristics of professional, well-resourced threat actors:

  1. Modular Design - Components can be deployed independently for flexibility
  2. Product-Specific Variants - CrowdStrike-specific killer suggests research investment
  3. Cryptographic Sophistication - RSA-OAEP + ChaCha20 hybrid encryption indicates expertise
  4. Rust Implementation - Modern language choice suggesting professional developers
  5. Per-Victim Key Management - RaaS model with decryptor proves operational maturity
  6. Test Variants - Multiple beta/test builds indicate continuous development
  7. Hardcoded Keys - Operational security lapses suggest rapid development cycles

Threat Intelligence Summary

Arsenal-237 Attribution Context

Threat Tier: PROFESSIONAL RANSOMWARE OPERATION (likely RaaS provider)

Operational Model: HIGHLY LIKELY (90%) - Ransomware-as-a-Service (RaaS)

Evidence:

  • Per-victim key architecture enables affiliate model
  • Builder ID tracking in enc_c2.exe
  • Professional development quality
  • Multiple variants for different scenarios
  • Decryption tool indicates revenue-sharing structure

Geographic Origin: INSUFFICIENT DATA - While Rust implementation and English-language strings are present, these are common across global threat actors and do not provide reliable geographic attribution. Tor-based C2 infrastructure intentionally obscures developer location.

Threat Activity Timeline: LIKELY (80%) - Active development underway

  • Multiple test/beta variants recovered (new_enc.exe v0.5-beta, full_test_enc.exe test version)
  • Indicates pre-deployment testing phase
  • Suggest operational deployment imminent or recently initiated

Infrastructure Assessment

C2 Infrastructure: Tor-based communication (enc_c2.exe)

  • CONFIRMED: Tor C2 beaconing observed in analysis
  • LIKELY (75%): Multiple hidden service addresses for redundancy
  • Reason: Blocks ISP/network-level detection

Hosting Model: LIKELY (75%) - Bulletproof hosting providers

  • Infrastructure resilience indicators suggest abuse-tolerant providers
  • Standard operational model for RaaS platforms

Strategic Defensive Recommendations

For Executive Leadership

Risk Acknowledgment: Arsenal-237 represents an EXISTENTIAL BUSINESS THREAT. If deployed within your infrastructure, this toolkit can:

  • Encrypt critical business data with cryptography that cannot be broken
  • Disable security products, making remediation nearly impossible
  • Persist across attempted cleanup and reboots
  • Enable lateral movement to critical systems
  • Demand ransom with credible threat of permanent data destruction

Recommended Strategic Actions:

  1. Escalate Security Investment to Board Level
    • Arsenal-237 is not a standard malware threat; it’s an operational attack platform
    • Recommend dedicating security resources as business-critical
    • Align with executive risk tolerance and business continuity requirements
  2. Establish Offline Backup Strategy
    • CRITICAL: If Arsenal-237 encrypts data, offline backups are your ONLY recovery option
    • Modern backups (Veeam, Commvault, etc.) should maintain 30-day snapshots
    • Air-gap backup infrastructure from production systems
    • Test recovery procedures quarterly
  3. Incident Response Plan Validation
    • Update IR procedures for ransomware-specific scenarios
    • Define escalation paths and decision-making authority
    • Establish communication protocols with law enforcement and cyber insurance
    • Conduct tabletop exercises at least semi-annually
  4. Cyber Insurance Alignment
    • Ensure coverage includes ransomware incident response and extortion threats
    • Verify policy covers forensic investigation and negotiation support
    • Understand policy exclusions and requirements (e.g., reporting timelines)
  5. Stakeholder Communication Plan
    • Prepare disclosure strategies for potential data loss scenarios
    • Coordinate with legal, PR, and regulatory compliance teams
    • Understand notification requirements under GDPR, CCPA, state laws

For Security Leadership & CISOs

Defensive Priority Framework:

Priority 1: Detection & Prevention (Prevention-First)

  • Objective: Prevent Arsenal-237 deployment before it reaches impact phase
  • Mechanisms:
    • EDR tools with behavioral monitoring and kernel-mode visibility
    • Network-level C2 detection for Tor traffic
    • Process injection detection (CreateRemoteThread, QueueUserAPC)
    • Privileged process elevation monitoring (lpe.exe variants)

Priority 2: Threat Hunting (Assume Breach)

  • Objective: Detect Arsenal-237 if prevention fails
  • Mechanisms:
    • Hunt for BYOVD exploitation attempts (BdApiUtil64.sys loading)
    • Monitor for rootkit installation (driver loading from unusual locations)
    • Behavioral hunt for security product termination
    • DLL hijacking detection (nethost.dll in unexpected locations)

Priority 3: Isolation & Containment (Rapid Response)

  • Objective: Stop ransomware spread once detected
  • Mechanisms:
    • Immediate network isolation of affected systems
    • Disable affected user accounts
    • Block C2 infrastructure at network perimeter
    • Preserve forensic evidence for investigation

Priority 4: Recovery Readiness (Assume Failure)

  • Objective: Minimize downtime if attack succeeds
  • Mechanisms:
    • Offline backup validation and recovery testing
    • System rebuild procedures pre-staged and tested
    • Critical data identification and protection prioritization
    • Business continuity for critical functions identified

For Security Operations Center (SOC) Teams

Detection Rules Priority:

See individual component reports for specific detection rules, YARA signatures, and hunting queries. Key detection areas:

  1. BYOVD Detection (Phase 1, Components 3-4)
    • Monitor for vulnerable driver loading (BdApiUtil64.sys)
    • Track lpe.exe execution and privilege escalation
    • Alert on kernel driver installation from non-system locations
  2. Security Product Termination (Phase 1, Components 1-2)
    • Monitor for taskkill targeting security products
    • Detect kernel-mode process termination
    • Flag unusual termination of EDR/antivirus processes
  3. Persistence Indicators (Phase 2, Components 6-7)
    • DLL hijacking detection (nethost.dll in user-writable locations)
    • Monitor .NET process loading unexpected DLLs
    • Browser process activity with credential access patterns
  4. Ransomware Behavior (Phase 3, Components 8-11)
    • File encryption activity (high entropy writes, file extension changes)
    • Tor traffic from systems (enc_c2.exe C2 communication)
    • Bulk file modification in short timeframes
    • Read-ahead pattern on backup systems

Investigation Procedures:

  1. If killer.dll or killer_crowdstrike.dll detected:
    • IMMEDIATE: Isolate system from network
    • Assume Phase 1 attack chain in progress
    • Begin forensic preservation
    • Escalate to incident response team
  2. If lpe.exe or BYOVD activity detected:
    • CRITICAL: System has likely been compromised with kernel access
    • Assume rootkit presence; standard user-mode tools inadequate
    • Perform forensic imaging before remediation
    • Plan for system rebuild (not cleanup)
  3. If chromelevator.exe or credential theft indicators detected:
    • HIGH: Credential compromise likely
    • Initiate credential rotation for affected users
    • Monitor for lateral movement from compromised accounts
    • Expand threat hunt to systems with credential access
  4. If ransomware encryption behavior detected:
    • CRITICAL: Begin IMMEDIATE isolation procedures
    • STOP: Do not attempt decryption; preserve encrypted files for forensic analysis
    • Identify offline backups for recovery
    • Document encryption patterns for decryption capability assessment

For Threat Hunting Teams

Hunt Scenarios:

  1. Hunt for BYOVD Exploitation Attempts
    • Search for unusual driver loading from temporary directories
    • Monitor kernel callback registrations
    • Track kernel mode code execution origins
    • See BdApiUtil64-sys.md report for detailed signatures
  2. Hunt for Rootkit Persistence Indicators
    • Kernel object hiding indicators (threads/processes enumeration gaps)
    • Driver installation anomalies
    • Unusual kernel API hooking patterns
    • See rootkit-dll.md report for indicators
  3. Hunt for DLL Hijacking Persistence
    • Monitor for nethost.dll in non-system directories
    • Track .NET process loading from user-writable paths
    • Identify unusual DLL version signatures
    • See nethost-dll.md report for signatures
  4. Hunt for Browser Credential Theft
    • Monitor browser process activity with file system access
    • Track credential store access patterns
    • Identify SQLite database reads (Chrome/Edge credential store)
    • See chromelevator-exe.md report for indicators
  5. Hunt for Ransomware Encryption Patterns
    • Monitor for bulk file access and modification
    • Track entropy patterns in file writes
    • Identify file extension changes or file system enumeration
    • See Phase 3 ransomware reports for encryption behavior signatures

FAQ - Addressing Common Questions

Technical Questions

Q1: “How is Arsenal-237 different from other ransomware families?”

Short Answer: Arsenal-237 is a complete operational attack platform, not just ransomware. It includes rootkit components (malware that operates at the deepest system level and hides itself from security tools) that make detection and remediation nearly impossible.

Detailed Explanation: Traditional ransomware families (like LockBit, BlackCat) focus primarily on encryption. Arsenal-237 is fundamentally different-it’s a multi-phase system designed to:

  1. Disable security products before encryption begins
  2. Establish deep system-level persistence that survives cleanup attempts
  3. Steal credentials for lateral movement
  4. Deploy highly sophisticated ransomware variants

The rootkit component (rootkit.dll) is the game-changer. While other ransomware can be removed by cleanup tools, Arsenal-237’s rootkit operates at the kernel level (the core of the operating system) and hides the malware itself from detection tools, making traditional remediation inadequate. This forces organizations toward complete system rebuild rather than cleanup.

Q2: “Can we decrypt files encrypted with full_test_enc.exe?”

Short Answer: NO. The military-grade hybrid encryption is cryptographically unbreakable without the threat actor’s private decryption key.

Detailed Explanation: The advanced ransomware variant (full_test_enc.exe) uses a two-layer encryption scheme that combines the strengths of two different encryption methods:

  1. Each file is encrypted with a symmetric key (like a master padlock key)
  2. That symmetric key is then encrypted using asymmetric cryptography (like locking the padlock key in a safe that only the attacker can open)
  3. Only the threat actor’s private key can unlock the safe to retrieve the padlock key
  4. Without the private key, the symmetric key remains locked
  5. Without the symmetric key, the file content remains encrypted

This is mathematically proven to be unbreakable. Decryption requires either:

  • Paying ransom for the threat actor’s private key (via dec_fixed.exe)
  • Restoring from offline backups
  • Law enforcement obtaining the private key (unlikely)

External decryption services CANNOT help. Brute-force is cryptographically infeasible (2^256 possible keys).

Q3: “Does the hardcoded key in new_enc.exe mean we can decrypt those files?”

Short Answer: POSSIBLY, but only if your organization was attacked with new_enc.exe specifically (a test/beta variant).

Detailed Explanation: The new_enc.exe variant contains a hardcoded ChaCha20 key (67e6096a…), which is a significant operational security failure. However:

  1. This variant is marked as “v0.5-beta,” indicating it’s a development version
  2. If this beta variant was used in actual attacks, affected organizations could potentially decrypt files
  3. Advanced variants like full_test_enc.exe do NOT have hardcoded keys; they use per-victim hybrid encryption
  4. Most operational deployments likely use the advanced variants, not the test versions

Check your files: If encrypted files are present, analysis can determine which variant was used. Early-stage attacks may have used test versions; later deployments almost certainly use advanced variants.

Q4: “What is RaaS (Ransomware-as-a-Service) and why does it matter?”

Short Answer: RaaS is a business model where threat actors provide ransomware and infrastructure to affiliates, similar to legitimate SaaS. It matters because Arsenal-237 is likely operating this way, which affects how the threat evolves.

Detailed Explanation: RaaS operations work like this:

  1. Core threat actor develops ransomware platform and maintains C2 infrastructure
  2. Affiliates purchase or are recruited to use the platform
  3. Core actor takes percentage of ransom payments (typically 30-40%)
  4. Affiliates conduct targeting and social engineering
  5. Each victim gets unique encryption keys and decryption tools

Arsenal-237’s evidence of RaaS:

  • Per-victim key architecture in dec_fixed.exe (different key from other samples)
  • Builder ID tracking in enc_c2.exe (enables affiliate tracking)
  • Multiple variants for different scenarios (flexibility for affiliates)

Why this matters for defenders:

  • RaaS = scalability, meaning more organizations attacked
  • Multiple affiliates = varied targeting and operational patterns
  • Per-victim keys = ransom payment is the only decryption option
  • Business model sustainability = ongoing development and improvement

Q5: “The reports mention ‘test builds’-does this mean the threat isn’t real yet?”

Short Answer: NO. Test builds indicate IMMINENT or RECENT operational deployment, not that the threat is theoretical.

Detailed Explanation: Test/beta builds (new_enc.exe v0.5-beta, full_test_enc.exe test version) mean:

  1. Threat actors are actively developing and testing variants
  2. Pre-deployment testing is underway or recently completed
  3. Operational deployment could begin/has begun shortly
  4. Indicates this is an ACTIVE threat, not a future concern

Timeline assessment: LIKELY (80%)

  • Test variants recovered suggests pre-deployment phase
  • Multiple variants under development simultaneously
  • Suggests operational timeline measured in weeks/months, not years

Operational Questions

Q6: “What should we do immediately if we detect Arsenal-237?”

Short Answer: (1) Isolate the affected system, (2) Preserve forensic evidence, (3) Assume worst-case impact (ransomware deployed), (4) Activate incident response plan.

Detailed Explanation: If ANY Arsenal-237 component is detected:

IMMEDIATE ACTIONS (Priority: CRITICAL):

  • Network isolation of affected system (physical disconnect or VLAN isolation)
  • Disable affected user accounts
  • Assume breach; activate IR team
  • Preserve system snapshot for forensics

INVESTIGATION PHASE (Priority: CRITICAL):

  • Search for related systems (same user account, similar attack patterns)
  • Identify credential compromise scope
  • Block known C2 infrastructure at network perimeter
  • Engage forensic team for evidence preservation

REMEDIATION PHASE (Priority: HIGH):

  • Forensic imaging of affected systems
  • Credential rotation for compromised accounts
  • Threat hunt across infrastructure for lateral movement
  • Engage cyber insurance and legal teams

See detailed procedures in individual component reports and Incident Response section below.

Q7: “Should we rebuild systems or attempt cleanup if Arsenal-237 is detected?”

Short Answer: REBUILD. The rootkit operates at the deepest system level, making standard cleanup inadequate for Arsenal-237 infections.

Detailed Explanation: Two options exist for remediation:

OPTION A: Complete System Rebuild (STRONGLY RECOMMENDED)

  • Wipe system and reinstall from clean media
  • Ensures rootkit removal (cannot be verified as removed from compromised system)
  • Only reliable method for kernel-mode malware
  • Business impact: 4-8 hour recovery per system
  • Recommendation: REQUIRED for systems with kernel-mode compromise

OPTION B: Aggressive Cleanup (SIGNIFICANTLY HIGHER RISK)

  • Attempt to remove malware files and registry entries
  • Risk: Rootkit remains undetected, malware persists
  • Risk: Cannot verify rootkit removal from compromised system
  • Not recommended for Arsenal-237 due to kernel-mode component

Rebuild is mandatory for any system where Phase 1 components (rootkit.dll, BYOVD exploitation) are confirmed. Cleanup is inadequate due to rootkit’s ability to hide itself.

Q8: “How long will it take to recover from an Arsenal-237 attack?”

Short Answer: Recovery time depends on backup strategy and ransomware variant used.

Detailed Explanation: Recovery timeline varies:

Best Case (Offline Backups Available):

  • System rebuild: 4-8 hours per system
  • Data restoration from backup: 24-72 hours depending on data volume
  • Verification and validation: 24-48 hours
  • Total: 3-7 days for organization-wide recovery

Worst Case (No Offline Backups):

  • Option 1: Ransom payment and decryption key usage (financial negotiation timeline, typically 2-7 days)
  • Option 2: Data loss and business disruption (indefinite; depends on business continuity alternatives)
  • Data reconstruction: weeks to months depending on recovery procedures

Critical factor: Offline backup strategy determines recovery speed and success. Organizations without offline backups have only two options: pay ransom or lose data.

Q9: “What is ‘offline backup’ and how do we implement it?”

Short Answer: Offline backup means backup storage that’s not connected to the network and cannot be encrypted by ransomware. Implement using air-gapped systems or cloud with immutable snapshots.

Detailed Explanation: Modern ransomware targets backup systems as part of attack (see Arsenal-237’s backup targeting in new_enc.exe). Offline backup strategies:

  1. Air-Gapped Local Backups
    • Daily/weekly backup to external storage
    • Storage physically disconnected after backup completes
    • Cannot be encrypted even if ransomware gains network access
    • Cost: Reasonable (external drives, tape systems)
    • Recovery time: 4-12 hours per system
  2. Cloud Backups with Immutability
    • Cloud provider (AWS, Azure, Google Cloud) with immutable snapshots
    • Immutability means backups cannot be deleted/encrypted once created
    • Requires proper permission segregation (ransomware cannot reach backup APIs)
    • Cost: Moderate (cloud storage costs)
    • Recovery time: 2-4 hours per system
  3. Hybrid Approach
    • Daily incremental backups to cloud (immutable)
    • Weekly full backups to air-gapped external storage
    • Combines availability (cloud) with security (air-gap)
    • Cost: Moderate
    • Recovery time: 2-4 hours (cloud) or 12-24 hours (external storage)

Recommendation: Implement both cloud immutable backups AND air-gapped external storage. Test recovery procedures quarterly.

Q10: “Can we detect Arsenal-237 before the ransomware phase?”

Short Answer: YES, if you have proper EDR, behavioral monitoring, and threat hunting programs.

Detailed Explanation: Detection opportunities exist at multiple phases:

Phase 1 (Best Detection Opportunity):

  • BYOVD exploitation attempts
  • Kernel driver loading from unusual locations
  • Privilege escalation attempts
  • Security product process termination

Phase 2 (Good Detection Opportunity):

  • DLL hijacking indicators
  • Browser credential access patterns
  • Unusual process loading behavior

Phase 3 (Last Detection Opportunity):

  • File encryption behavior
  • Bulk file system access
  • Tor C2 traffic (enc_c2.exe)

Requirements for detection:

  • EDR Tool with kernel-mode visibility (CrowdStrike, Microsoft Defender, SentinelOne, etc.)
  • Behavioral Monitoring for suspicious privilege escalation and process injection
  • Threat Hunting Program actively searching for indicators
  • Network Monitoring for C2 traffic detection

Confidence level: HIGH (85%) - Organized, mature detection programs will identify Arsenal-237 during Phase 1 or Phase 2 before encryption begins.

Business/Risk Questions

Q11: “What’s the financial impact if we’re attacked with Arsenal-237?”

Short Answer: Business impact varies from millions (if ransomware deploys) to tens of millions (if critical data is permanently lost).

Detailed Explanation: Financial impact categories:

  1. Direct Ransom Cost
    • Typical ransomware ransom: Negotiated (varies 5x to 100x+ based on organization size)
    • Statistical estimate: Most organizations pay rather than face permanent data loss
  2. Incident Response Costs
    • Forensic investigation: 2-4 weeks, specialized teams
    • Legal/compliance consultation: Breach notification, regulatory reporting
    • PR/reputation management: Potential lasting damage
    • Estimate: Hundreds of thousands to millions
  3. Business Disruption Costs
    • Operational downtime: 3-7 days during recovery
    • Lost productivity: All affected systems offline
    • Customer/partner impact: SLAs violated, relationships damaged
    • Estimate: Millions depending on industry and organization size
  4. Long-Term Impacts
    • Compliance violations: Regulatory fines (GDPR, HIPAA, etc.)
    • Customer/partner liability: Contractual penalties
    • Reputation damage: Market perception, future business impact
    • Insurance costs: Premiums increase post-incident

Total estimated impact: 5M to 50M+ depending on industry, organization size, and recovery success.

Critical factor: Offline backup strategy reduces financial impact dramatically (recovery vs. ransom payment).

Key Takeaways

What Arsenal-237 Means for Your Organization

1. This Is a Professional Attack Platform, Not Just Malware Arsenal-237 is a complete operational system designed by sophisticated threat actors. It’s not a single malware variant but a coordinated toolkit spanning from initial compromise to final impact. This level of sophistication indicates well-resourced threat actors with professional development processes.

Implication: Standard remediation procedures and general security controls are inadequate. Organizations must implement defense-in-depth strategies accounting for deep system-level threats and sophisticated evasion techniques.

2. Your Backups Are the Only Reliable Recovery Option The advanced ransomware variants use military-grade hybrid encryption that is cryptographically impossible to break-not by security researchers, government agencies, or any commercial service. There is no “magic” decryption solution. Recovery depends entirely on:

  • Offline, air-gapped backup systems
  • Successful ransom negotiation and key payment
  • Law enforcement intervention (unlikely)

Implication: Organizations without robust offline backups face binary choice: pay ransom or lose data permanently. Backup strategy is now a critical business continuity component.

3. Prevention Is Possible But Requires Advanced Capabilities Detection of Arsenal-237 is achievable during Phase 1 or Phase 2 (before ransomware encryption) IF organizations have:

  • Modern EDR (Endpoint Detection and Response) tools with deep system visibility
  • Behavioral monitoring and threat hunting capabilities
  • Incident response procedures for rapid isolation

Implication: Investing in EDR, behavioral monitoring, and threat hunting programs provides concrete protection against this threat. Detection before Phase 3 prevents encryption and makes recovery simple.

4. Time-to-Remediation Is Critical The toolkit’s multi-phase design means there are multiple opportunities for detection and stopping the attack:

  • Phase 1: Privilege escalation and security product disabling
  • Phase 2: Persistence and credential theft
  • Phase 3: Ransomware encryption (last chance before impact)

Early detection dramatically reduces impact. Each phase takes hours to days, providing incident response teams with opportunity windows.

Implication: Mature incident response capabilities and threat hunting programs are essential. Organizations that can detect and isolate during Phase 1 or Phase 2 will avoid the costly Phase 3 impact.

5. This Attack Is Likely Targeted at Your Industry The Arsenal-237 toolkit’s sophistication and development investment indicates threat actors are targeting organizations where ransom payments are economically viable. Industries at highest risk:

  • Healthcare (ransomware disruption = patient care impact, higher ransom)
  • Financial services (regulatory pressure, economic leverage)
  • Manufacturing (production disruption, supply chain impact)
  • Large enterprises (resources to pay ransom)

Implication: If your organization is in a high-value industry or has significant operational data, Arsenal-237 should be prioritized in your threat model. Assume targeted interest and adjust defenses accordingly.

6. User Training Alone Is Inadequate Defense Some organizations assume “our users are trained” or “our culture prevents clicking links” provides protection. Arsenal-237 demonstrates that traditional security assumptions are insufficient:

  • BYOVD (Bring Your Own Vulnerable Driver) techniques use legitimate, signed drivers that bypass signature-based detection
  • Credential theft (chromelevator.exe) enables inside-the-perimeter attacks
  • The rootkit operates at a level deeper than standard security controls can detect
  • Social engineering is only one attack vector among many

Implication: Defense-in-depth, technical controls, and detection capabilities are non-negotiable. User training is necessary but insufficient. Implement technical compensating controls for human error.

Confidence Levels Summary

Findings Organized by Confidence Level

CONFIRMED (Highest Confidence - Direct Observation)

  • Arsenal-237 toolkit contains 11 distinct malware components
  • BYOVD exploitation using BdApiUtil64.sys driver confirmed
  • Rootkit (rootkit.dll) capable of process/thread/driver hiding at the kernel level
  • Military-grade hybrid encryption in full_test_enc.exe (combines two encryption methods for maximum strength)
  • Hardcoded encryption key in new_enc.exe (67e6096a… - a significant security flaw in this test variant)
  • Per-victim decryption keys in dec_fixed.exe (different key: 1e0d8597…)
  • Tor-based C2 communication in enc_c2.exe
  • Rust implementation across ransomware components
  • Security product termination capability via killer.dll and killer_crowdstrike.dll
  • DLL hijacking persistence via nethost.dll

HIGHLY LIKELY (90-95% Confidence - Strong Corroborating Evidence)

  • Arsenal-237 operates as Ransomware-as-a-Service platform (per-victim key model, affiliate tracking)
  • Threat actors have professional development capabilities (multiple variants, iterative testing)
  • CrowdStrike-specific targeting indicates research investment in EDR products
  • Test/beta variants indicate pre-deployment testing phase
  • Operational timeline: Active development underway (likely weeks/months before major deployment campaign)
  • Kernel-mode rootkit defeats standard user-mode detection tools (makes remediation require full rebuild)

LIKELY (75-90% Confidence - Reasonable Inference)

  • Threat actors are US/EU based or operating from jurisdiction with lower law enforcement risk
  • Multiple affiliate groups likely using Arsenal-237 platform for decentralized attacks
  • Enterprise organizations are primary targets (backup targeting, employee credential theft)
  • Tor infrastructure suggests persistent threat actor operation (not one-off campaign)

POSSIBLE (50-75% Confidence - Analytical Judgment)

  • Arsenal-237 may be associated with specific known threat actor group (insufficient attribution evidence)
  • Development team size likely 5-15 people (code sophistication and multi-variant development)
  • Operational timeline: First major campaign deployment possible within 60 days of report date

Incident Response Procedures

If Arsenal-237 Has Been Detected (CONFIRMED Infection)

**IMMEDIATE ACTIONS (Priority: CRITICAL Resource Intensity: CRITICAL)**
  • ISOLATE SYSTEM - Disconnect affected system from network (physical disconnect preferred)
  • NOTIFY IR TEAM - Alert incident response leadership; activate IR procedures
  • DISABLE ACCOUNT - Disable user account of affected system from domain controller
  • PRESERVE EVIDENCE - DO NOT REBOOT SYSTEM; begin forensic image capture
  • BLOCK C2 - If C2 IP/domain identified, add to firewall block list immediately
  • ESCALATE - Notify CISO, legal team, and cyber insurance provider
**PRIORITY 1: INVESTIGATION (Priority: CRITICAL Resource Intensity: HIGH)**
  • Determine which Arsenal-237 components are present (Phase 1, 2, or 3)
  • Search network for related systems (same user, same timing, lateral movement indicators)
  • If Phase 3 detected: DO NOT ATTEMPT DECRYPTION; preserve encrypted files for forensics
  • Identify scope of compromise (other systems, affected users)
  • Assess impact: Are critical files encrypted? Is ransomware progressing?
**PRIORITY 2: CONTAINMENT (Priority: CRITICAL Resource Intensity: HIGH)**
  • Isolation procedures:
    • Affected systems isolated from network
    • Compromised user accounts disabled
    • Lateral movement containment (block credential access from affected systems)
  • Threat hunting across infrastructure:
    • Search for other Phase 1 indicators (BYOVD, kernel driver loading)
    • Search for Phase 2 indicators (DLL hijacking, credential access)
    • Search for Phase 3 indicators (encryption behavior, Tor traffic)
  • Forensic imaging of affected systems (before remediation attempts)
**PRIORITY 3: REMEDIATION DECISION (Priority: CRITICAL Resource Intensity: CRITICAL)**

Determine remediation approach based on compromise phase:

  • If ONLY Phase 1-2 detected (no encryption observed yet):
    • Kernel-mode rootkit may be present
    • RECOMMENDED: Complete system rebuild (do not attempt cleanup)
    • Monitor for Phase 3 indicators in parallel
  • If Phase 3 detected (encryption in progress or completed):
    • CRITICAL: Assume data loss; offline backups are recovery option
    • Isolate backup systems immediately (prevent encryption spread)
    • Initiate backup restoration procedures
    • Determine: Rebuild vs. Cleanup decision (see below)

PHASE 3 REMEDIATION DECISION MATRIX:

Factor Rebuild Recommended Cleanup Possible (Higher Risk)
Kernel-mode rootkit present YES (mandatory rebuild) NO (cleanup inadequate)
Phase 3 ransomware detected PREFERRED (faster, safer) POSSIBLE (if offline backups available)
Backup restoration available PREFERRED (rebuild + restore) ACCEPTABLE (parallel approach)
No backup available STILL RECOMMENDED ONLY OPTION (if not paying ransom)

Related Resources & Further Reading

Individual Component Reports

Access detailed technical analysis for each toolkit component:

  1. Phase 1 - Defense Evasion Components:
  2. Phase 2 - Persistence & Credential Access Components:
  3. Phase 3 - Ransomware Components:

Detection & Hunting Resources

  • IOC Feeds: See individual component reports for file hashes, C2 infrastructure, and behavioral indicators
  • YARA Rules: See individual component reports for malware detection signatures
  • Hunting Queries: See individual component reports for SIEM/EDR hunting procedures
  • Network Signatures: See individual component reports for Suricata/Snort rules

External References

  • MITRE ATT&CK: Framework for mapping Arsenal-237 techniques to standard threat categories
    • Privilege Escalation (T1134, T1543)
    • Persistence (T1547, T1574, T1547.014)
    • Credential Access (T1555, T1040)
    • Impact (T1486, T1491)
  • Ransomware-as-a-Service Research:
    • Provides context for Arsenal-237’s operational model
    • Documents typical RaaS platform architecture and affiliate structures
    • Reference: Ongoing threat intelligence from CISA, FBI, Europol

License

(c) 2026 Arsenal-237 Malware Analysis. All rights reserved.

This report is provided for informational and defensive purposes. Reuse or distribution requires written permission.