Nightspire — Technical Analysis / Cti Report

Scope statement: this analysis covers a single Go-compiled sample (SHA-256 in §1). Findings describe what was observed in this binary; they do not imply that all NightSpire deployments share identical implementation details. Family-level claims are restricted to indicators flagged as Family in §13.

Reading convention: the markers **Observed:** and **Inferred:** are used throughout this brief to separate facts read directly from the binary from analytical extrapolation.

1. Executive Summary

2. Notable Observations

2.1 Intermittent encryption exposes file size intelligence

Observed: function main.getEncryptionType @ 0x50fc80 implements three-tier file processing based on file size thresholds: - Type 1: Files ≤100MB (0x6400000) — complete encryption in sequential 1MB chunks - Type 2: 100MB-1.6TB (0x1900000000) — first 1GB complete + distributed 1MB chunks with calculated spacing - Type 3: Files >1.6TB — first 1GB complete + distributed 1GB chunks with calculated spacing

Observed: the algorithm reveals organizational data structure through encryption timing patterns. Function main.startEncrypting @ 0x510aa0 shows distinct code paths: Type 1 uses 0x100000 (1MB) chunk size in sequential loop, Type 2/3 use 0x40000000 (1GB) for initial complete encryption followed by distributed chunk processing.

Inferred — operational implication: large file processing creates distinct behavioral signatures. Database files, backup archives, and media collections receive partial encryption, enabling defender triage based on encryption duration patterns.

2.2 Parallel goroutine architecture creates detection window

Observed: main execution in main.main @ 0x511d40 spawns 26 concurrent goroutines via Go's sync.WaitGroup, one per Windows drive letter (A: through Z:). Each goroutine calls main.EncryptDir @ 0x511260 for recursive directory processing.

Observed: volume enumeration occurs via sequential FindFirstVolumeW/FindNextVolumeW calls before goroutine spawn, creating burst of volume API activity measurable via ETW/EDR telemetry.

Inferred — operational implication: the sequential volume enumeration phase provides a detection window before parallel encryption begins. High-volume calls to Windows volume APIs from a single process create distinctive behavioral signature.

2.3 Configuration stored as plaintext Go strings

Observed: all infrastructure and configuration elements stored as cleartext strings in PE .rdata section without encryption or obfuscation: - Onion URLs: literal strings at 0x5a24cb range - Authentication credentials: NSPIRE830NPH7ZLBRW39 / 769FZisalII12Rph at static offsets - RSA public key: base64 blob at 0x5afa9e - File extension: .nspire string literal - Contact emails: full addresses as string constants

Inferred — operational implication: static string extraction enables complete infrastructure mapping without dynamic analysis or decryption. YARA signatures can reliably target these embedded constants across builds.

2.4 File signature system prevents double-encryption

Observed: function main.checkPossibility @ 0x50f8c0 implements signature checking by seeking to file end and reading for "sNightspire" marker. Function main.writeToTail @ 0x50ffa0 appends this signature after encryption.

Observed: the signature check occurs before encryption logic in main.startEncrypting, creating early-exit path for files already processed.

Inferred — operational implication: the signature system enables identification of encrypted files and prevents encryption loops. The "sNightspire" marker is visible in hex editors at file tail, providing forensic pivot for encrypted file identification.

2.5 CLI configuration suggests automation

Observed: extensive command-line argument parsing in main.main with 7 distinct flags: - -p <path>: target specific directory - -e <mode>: encryption method toggle (0/1) - -s <flag>: AppData folder skip control - -r <mode>: ransom note placement method - -t <seconds>: throttling via sleep intervals - -k <count>: thread/goroutine count control - -noreadme: disable ransom note creation

Inferred — operational implication: the extensive CLI interface suggests deployment automation or affiliate model usage. The -k thread count parameter includes corruption warnings in help text, indicating operational risk awareness.

2.6 No anti-analysis or evasion techniques

Observed: binary analysis reveals no dedicated anti-analysis implementations: - No string obfuscation (all constants in cleartext) - No API hashing or import obfuscation - No debugging detection logic - No virtual machine detection - No process injection or hollowing - No persistence mechanisms - Standard Go runtime with unmodified entry point _rt0_amd64_windows @ 0x4749a0

Inferred — operational implication: transparent implementation suggests confidence in cryptographic strength over evasion. Detection and analysis remain straightforward without anti-analysis circumvention requirements.

3. Code-level fingerprints

Stable artefacts observable across builds of this family:

Sample-specific (non-stable across builds):

Observed: the chat credentials appear to be per-sample unique based on the specific UUID/password combination embedded in this binary.

4. Execution Timeline (T0 → encryption)

Observed sequential operations from code analysis:

T+0.0   Go runtime initialization (_rt0_amd64_windows entry point)
T+0.1   Command-line argument parsing (flag package)  
T+0.2   Drive enumeration via FindFirstVolumeW/FindNextVolumeW sequence
T+0.5   Goroutine spawn (26 parallel workers, A: through Z: drives)
T+1.0   sync.WaitGroup initialization for goroutine coordination
T+2.0   Parallel directory walking begins (main.EncryptDir per goroutine)
T+3.0   File extension filtering and exclusion logic per file
T+5.0   File signature checking (main.checkPossibility) 
T+10.0  AES key generation (main.GenerateRandomKey @ 0x50f480)
T+10.1  AES nonce generation (main.GenerateRandomNonce @ 0x50f500)
T+10.2  RSA key wrapping (main.EncryptRSA @ 0x50f7a0)
T+10.5  File encryption begins (main.encryptMethod @ 0x50f620)
        ├ Type 1: Sequential 1MB chunks
        ├ Type 2: First 1GB + distributed 1MB chunks  
        └ Type 3: First 1GB + distributed 1GB chunks
T+N     File signature append (main.writeToTail)
T+N+0.1 Extension change to .nspire (main.changeFileName @ 0x510260)
T+N+0.2 Icon configuration (optional, main.setFileIcon @ 0x50eae0)
T+N+1.0 Ransom note creation (main.MakeReadMeFile @ 0x510860)
T+Final Windows Explorer refresh (main.refreshWindowsExplorer @ 0x50ef00)

Inferred timing: volume enumeration burst (T+0.2) provides earliest detection opportunity. Execution timing varies significantly based on filesystem size, file count, and storage performance.

5. TTP Highlights for Defender Workflow

5.1 Pre-encryption indicators (high precision, low FP)

Observed: the volume enumeration phase provides the most reliable early detection signal before file modification begins.

5.2 During-encryption indicators

6. MITRE ATT&CK Matrix

Observed techniques in this binary:

Notably absent: - T1055 (Process Injection) — No injection capabilities observed - T1112 (Modify Registry) — Minimal registry interaction beyond file associations - T1490 (Inhibit System Recovery) — No VSS deletion or backup removal - T1562 (Impair Defenses) — No security tool disabling - T1059 (Command Line Scripting) — Go binary, not script-based

7. Hunting Queries

7.1 Splunk SPL — Volume enumeration detection

index=sysmon EventCode=1 
| where match(Image, "(?i).*\.exe$")
| where match(CommandLine, "(?i).*(FindFirstVolume|FindNextVolume|GetVolumeInformation).*") OR match(ProcessName, "(?i).*go.*")
| stats count, values(CommandLine) by Computer, ParentImage, ProcessName
| where count >= 10

7.2 KQL — File extension mass change

DeviceFileEvents
| where Timestamp > ago(1h)
| where FileName endswith ".nspire"
| summarize NspireFiles = count(), 
            FirstFile = min(Timestamp),
            LastFile = max(Timestamp),
            SamplePaths = make_set(FolderPath, 10)
            by DeviceName
| where NspireFiles >= 50
| extend EncryptionDuration = LastFile - FirstFile

7.3 KQL — Go runtime process detection

DeviceProcessEvents
| where Timestamp > ago(24h)
| where ProcessCommandLine contains "_rt0_amd64_windows" 
     or InitiatingProcessCommandLine contains "go run"
     or ProcessVersionInfoOriginalFileName contains "go"
| join kind=leftouter (
    DeviceFileEvents 
    | where FileName endswith ".nspire"
) on DeviceName
| where isnotnull(FileName)

8. Sigma Rules

title: NightSpire Volume Enumeration Pattern
id: a1b2c3d4-e5f6-7890-abcd-ef1234567890
status: experimental
description: |
  Detects NightSpire ransomware volume enumeration phase through high-frequency
  Windows volume API calls from a single process, preceding .nspire file creation
logsource:
  product: windows
  category: process_creation
detection:
  selection_volume_apis:
    EventID: 1
    Image: '*'
  condition: selection_volume_apis
falsepositives:
  - Disk management utilities
  - System maintenance tools
level: high
tags:
  - attack.discovery
  - attack.t1083

---
title: NightSpire File Extension Creation
id: b2c3d4e5-f6g7-8901-bcde-f23456789012  
description: Mass creation of .nspire file extensions
logsource:
  product: windows
  category: file_event
detection:
  selection:
    EventID: 11
    TargetFilename: '*.nspire'
  condition: selection
level: critical
tags:
  - attack.impact
  - attack.t1486

9. Detection Confidence Matrix

10. Memory Artefacts (DFIR / live response)

Observed artefacts present in running process memory:

Live-response priority: if the process can be memory-imaged during encryption, individual file AES keys may be recoverable from the Go runtime heap, enabling decryption of files being processed at capture time.

Technical caveat: Go's garbage collector and memory layout make key recovery challenging compared to C/C++ implementations. Success depends on capture timing and heap analysis tools capable of parsing Go runtime structures.

11. Defender Priority Queue

P0 (immediate)

1. Isolate any host showing volume enumeration burst pattern or .nspire file creation
2. Memory dump active Go processes matching runtime signature before self-termination
3. Block outbound connections to .onion domains at network boundary
4. Preserve any /[NSPIRE_MSG].txt files for infrastructure intelligence

P1 (≤1 h)

1. Hunt for additional .nspire files across file shares and network storage
2. Audit volume enumeration patterns across SIEM for additional compromised hosts
3. Collect disk forensics images before encrypted file overwrite
4. Monitor network traffic for qTox protocol usage (backup communication channel)

P2 (≤24 h)

1. Reconstruct attack timeline using volume API call timestamps
2. Correlate file modification times to identify encryption sequence and duration
3. Test backup integrity and develop recovery procedures
4. Update detection signatures based on observed IOCs

P3 (post-incident)

1. Analyze encryption algorithm implementation for recovery possibilities
2. Cross-reference infrastructure IOCs with external threat intelligence
3. Develop long-term monitoring for NightSpire family evolution
4. Document lessons learned for incident response procedures

12. Observables Summary

13. Conclusion

Observed facts about this sample:

• Self-identified as NightSpire.Team via embedded strings (.nspire extension, team identifier in attack banner, contact emails, dual onion infrastructure for negotiation and data leak operations).
• Go 1.24.11 compilation with transparent string storage and no obfuscation techniques; standard Go runtime initialization via _rt0_amd64_windows entry point.
• Hybrid encryption: AES-256-CTR for file content with per-file key generation, RSA-4096-OAEP-SHA512 for key wrapping using embedded public key, intermittent encryption algorithm with three file-size tiers (100MB, 1.6TB thresholds).
• Parallel execution architecture: 26 goroutines for simultaneous drive processing (A: through Z:), configurable threading via CLI parameters, sync.WaitGroup coordination.
• File signature system: "sNightspire" marker appended to prevent double-encryption, signature checking in main.checkPossibility before processing.
• No lateral movement, no exfiltration code, no anti-analysis techniques, no persistence mechanisms — focused single-stage encryption payload.

Inferred: the implementation is consistent with modern ransomware development using Go for cross-platform compatibility and memory safety. The extensive CLI interface suggests deployment automation or affiliate distribution models.

Sample-specific artifacts (not portable to other builds): the RSA-4096 public key, chat credentials UUID/password pair, and qTox IDs embedded in this sample. Infrastructure elements (onion URLs, email addresses) may persist across builds but require validation per sample.