malware-analyst

by solomonneas

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SKILL.md About

---
name: malware-analyst
version: 1.0.0
description: "Expert malware analysis for defensive security research. Static and dynamic analysis, sandbox triage, IOC extraction, unpacking, and malware family identification. Covers string extraction, import analysis, behavioral analysis, and incident response workflows."
metadata:
  model: opus
---

# File identification
file sample.exe
sha256sum sample.exe

# String extraction
strings -a sample.exe | head -100
FLOSS sample.exe  # Obfuscated strings

# Packer detection
diec sample.exe   # Detect It Easy
exeinfope sample.exe

# Import analysis
rabin2 -i sample.exe
dumpbin /imports sample.exe
```

### Phase 3: Static Analysis
1. **Load in disassembler**: IDA Pro, Ghidra, or Binary Ninja
2. **Identify main functionality**: Entry point, WinMain, DllMain
3. **Map execution flow**: Key decision points, loops
4. **Identify capabilities**: Network, file, registry, process operations
5. **Extract IOCs**: C2 addresses, file paths, mutex names

### Phase 4: Dynamic Analysis
```
1. Environment Setup:
   - Windows VM with common software installed
   - Process Monitor, Wireshark, Regshot
   - API Monitor or x64dbg with logging
   - INetSim or FakeNet for network simulation

2. Execution:
   - Start monitoring tools
   - Execute sample
   - Observe behavior for 5-10 minutes
   - Trigger functionality (connect to network, etc.)

3. Documentation:
   - Network connections attempted
   - Files created/modified
   - Registry changes
   - Processes spawned
   - Persistence mechanisms
```

## Use this skill when

- Working on file identification tasks or workflows
- Needing guidance, best practices, or checklists for file identification

## Do not use this skill when

- The task is unrelated to file identification
- You need a different domain or tool outside this scope

## Instructions

- Clarify goals, constraints, and required inputs.
- Apply relevant best practices and validate outcomes.
- Provide actionable steps and verification.
- If detailed examples are required, open `resources/implementation-playbook.md`.

## Common Malware Techniques

### Persistence Mechanisms
```
Registry Run keys       - HKCU/HKLM\Software\Microsoft\Windows\CurrentVersion\Run
Scheduled tasks         - schtasks, Task Scheduler
Services               - CreateService, sc.exe
WMI subscriptions      - Event subscriptions for execution
DLL hijacking          - Plant DLLs in search path
COM hijacking          - Registry CLSID modifications
Startup folder         - %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup
Boot records           - MBR/VBR modification
```

### Evasion Techniques
```
Anti-VM                - CPUID, registry checks, timing
Anti-debugging         - IsDebuggerPresent, NtQueryInformationProcess
Anti-sandbox           - Sleep acceleration detection, mouse movement
Packing                - UPX, Themida, VMProtect, custom packers
Obfuscation           - String encryption, control flow flattening
Process hollowing      - Inject into legitimate process
Living-off-the-land    - Use built-in tools (PowerShell, certutil)
```

### C2 Communication
```
HTTP/HTTPS            - Web traffic to blend in
DNS tunneling         - Data exfil via DNS queries
Domain generation     - DGA for resilient C2
Fast flux             - Rapidly changing DNS
Tor/I2P               - Anonymity networks
Social media          - Twitter, Pastebin as C2 channels
Cloud services        - Legitimate services as C2
```

## Tool Proficiency

### Analysis Platforms
```
Cuckoo Sandbox       - Open-source automated analysis
ANY.RUN              - Interactive cloud sandbox
Hybrid Analysis      - VirusTotal alternative
Joe Sandbox          - Enterprise sandbox solution
CAPE                 - Cuckoo fork with enhancements
```

### Monitoring Tools
```
Process Monitor      - File, registry, process activity
Process Hacker       - Advanced process management
Wireshark            - Network packet capture
API Monitor          - Win32 API call logging
Regshot              - Registry change comparison
```

### Unpacking Tools
```
Unipacker            - Automated unpacking framework
x64dbg + plugins     - Scylla for IAT reconstruction
OllyDumpEx           - Memory dump and rebuild
PE-sieve             - Detect hollowed processes
UPX                  - For UPX-packed samples
```

## IOC Extraction

### Indicators to Extract
```yaml
Network:
  - IP addresses (C2 servers)
  - Domain names
  - URLs
  - User-Agent strings
  - JA3/JA3S fingerprints

File System:
  - File paths created
  - File hashes (MD5, SHA1, SHA256)
  - File names
  - Mutex names

Registry:
  - Registry keys modified
  - Persistence locations

Process:
  - Process names
  - Command line arguments
  - Injected processes
```

### YARA Rules
```yara
rule Malware_Generic_Packer
{
    meta:
        description = "Detects common packer characteristics"
        author = "Security Analyst"

strings:
        $mz = { 4D 5A }
        $upx = "UPX!" ascii
        $section = ".packed" ascii

condition:
        $mz at 0 and ($upx or $section)
}
```

## Reporting Framework

### Analysis Report Structure
```markdown
# Malware Analysis Report

## Executive Summary
- Sample identification
- Key findings
- Threat level assessment

## Sample Information
- Hashes (MD5, SHA1, SHA256)
- File type and size
- Compilation timestamp
- Packer information

## Static Analysis
- Imports and exports
- Strings of interest
- Code analysis findings

## Dynamic Analysis
- Execution behavior
- Network activity
- Persistence mechanisms
- Evasion techniques

## Indicators of Compromise
- Network IOCs
- File system IOCs
- Registry IOCs

## Recommendations
- Detection rules
- Mitigation steps
- Remediation guidance
```

## Ethical Guidelines

### Appropriate Use
- Incident response and forensics
- Threat intelligence research
- Security product development
- Academic research
- CTF competitions

### Never Assist With
- Creating or distributing malware
- Attacking systems without authorization
- Evading security products maliciously
- Building botnets or C2 infrastructure
- Any offensive operations without proper authorization

## Response Approach

1. **Verify context**: Ensure defensive/authorized purpose
2. **Assess sample**: Quick triage to understand what we're dealing with
3. **Recommend approach**: Appropriate analysis methodology
4. **Guide analysis**: Step-by-step instructions with safety considerations
5. **Extract value**: IOCs, detection rules, understanding
6. **Document findings**: Clear reporting for stakeholders

_meta.json Metadata

{
  "ownerId": "kn74rr89530csqv49yzqn2htd1837ktx",
  "publishedAt": 1774008962227,
  "slug": "malware-analyst",
  "version": "1.0.1"
}