Hash Investigation

hash-investigation

Investigate a file hash end-to-end. Chain lookups, surface malware family attribution, prioritize infrastructure pivots, and decide whether deeper malware analysis is warranted.

This skill invokes: /lookup-virustotal, /lookup-otx, optionally /lookup-reversinglabs (vendor-authoritative classification + MITRE ATT&CK + sandbox), optionally /lookup-crowdstrike (Falcon Intel verdict + actor/malware attribution), optionally /lookup-misp and/or /lookup-opencti (internal correlation), optionally /malware-analysis, then /source-assessment, /tlp-guide, /confidence-levels.

When to invoke

• User asks to check a hash, identify malware, or enrich a sample
• Another skill surfaces a hash during investigation (e.g., /ip-investigation found communicating files)
• User asks "what is this malware" with a hash as input

Inputs

indicator: 
context: 
tlp_ceiling: 
request_malware_analysis: 

Procedure

1. Validate

• Confirm the hash is a valid length (MD5=32, SHA-1=40, SHA-256=64 hex chars)
• Reject if not; route to correct skill if it looks like a different indicator type

2. Parallel lookups

Always run (free / commonly available):

/lookup-virustotal hash     # detection stats, family, behavior tags
/lookup-otx hash            # community pulses, campaign attribution

Add to the same parallel batch if credentials are configured — don't demote these to "later, maybe":

/lookup-reversinglabs hash  --av-scanners --ticloud   # if $REVERSINGLABS_USER is set. Vendor-authoritative verdict + threat name + AV detection ratio. RL is the strongest single-source verdict on a hash; run it whenever available, not just when VT signal is thin.
/lookup-crowdstrike indicator                         # if $CROWDSTRIKE_CLIENT_ID is set. Falcon Intel verdict — malicious confidence + the threat actors and malware families CrowdStrike links to this hash + report refs. One API call.
/lookup-misp search-attributes --value                # if $MISP_URL + $MISP_KEY are set. Internal correlation against your own catalogued events.
/lookup-opencti lookup                                # if $OPENCTI_URL + $OPENCTI_TOKEN are set. Internal correlation against your OpenCTI knowledge base (observables + indicators in one call).

Escalation lookup (run sequentially after the parallel batch only if the call below is warranted):

/lookup-reversinglabs report  --detailed              # when you need MITRE ATT&CK mapping, sandbox detonation output, or networkthreatintelligence (C2 indicators extracted from the sample). Heavier than `hash` — use when classification alone is not enough.

3. Check if known-benign

If VirusTotal detection ratio is 0/Y with Y>30, AND OTX has no pulses, AND the file has standard legit characteristics (signed by major vendor, common packaging), treat as likely-benign. Stop and summarize. Don't spend analyst time.

4. Consolidate

indicator: 
type: hash
hash_type: md5 | sha1 | sha256
consolidated_verdict: malicious | suspicious | clean | unknown
detection_stats:
  vt_ratio: 
  first_seen: 
  last_analysis: 
  names: []
classification:
  malware_family: 
  tags: []
  attributed_actor: 
file_details:
  type: 
  size: 
  packers: []
  signed: 
  signer: 
behavior_summary:
  sandbox_verdicts: 
  notable_behaviors: []
  mitre_techniques: []
community_context:
  otx_pulse_count: 
  campaign_references: []
pivot_candidates:
  - type: ip
    value: 
    reason: c2_comm
  - type: domain
    value: 
    reason: c2_comm
  - type: hash
    value: 
    reason: child_parent

5. Prioritize pivots

1. C2 IPs / domains from communicatingfiles / contacteddomains — active infrastructure
2. Parent hashes (droppers / packers) — same campaign lineage
3. Dropped hashes (payloads) — behavioral family
4. YARA rule matches (if VT exposes them) — strong family clustering
5. Command-line strings — targeting / configuration hints

6. Decide on deeper analysis

If detection ratio is high and malware family is known, the lookup may be sufficient. If the hash is novel (low VT detection, recent first_seen, no known family), invoke /malware-analysis for a structural and behavioral review.

Also invoke /malware-analysis if:

• User explicitly asked for analysis (request_malware_analysis: true)
• This is part of a targeted incident response, not routine IOC triage

7. Apply rigor

Chain:

• /source-assessment
• /tlp-guide
• /confidence-levels

8. Return

title: "Hash Investigation: "
tlp: AMBER
confidence: 
summary: 
verdict: 
detection_stats: 
classification: 
file_details: 
behavior_summary: 
community_context: 
pivot_candidates: 
source_ratings: 
investigation_date: 
recommended_next_steps:
  - 

Special cases

• Hash not found in VT — doesn't mean clean. Could be very new, rare, or deleted. Check OTX; escalate to /malware-analysis if user has the sample.
• VT detection very low (1-2 engines) — often false positive or generic heuristic. Downgrade source rating; don't alarm the user without corroboration.
• Signed by legit vendor but flagged — possible supply-chain scenario. Flag for special review.

Related skills

• /ip-investigation, /domain-investigation, /url-investigation
• /malware-analysis — for novel or targeted samples
• /yara-writing — if the sample should produce a detection rule
• /indicator-pivoting — multi-hop IOC graphing
• /cti-orchestrator

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Liberty91LTD
• Source: Liberty91LTD/cti-skills
• License: MIT
• Homepage: https://liberty91.com/cti-skills

Install and usage instructions live in the source repository linked above.