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- Add scripts/agent.py and references/api-reference.md to all remaining skills - Update all 648 LICENSE files: copyright now reads 'Mahipal' - Add implementing-security-monitoring-with-datadog (new skill with full anatomy) - All 649 skills now have: SKILL.md, LICENSE, scripts/agent.py, references/api-reference.md
100 lines
2.5 KiB
Markdown
100 lines
2.5 KiB
Markdown
# API Reference: Suspicious PowerShell Execution Detection
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## Windows PowerShell Event Logs
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### Event IDs
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| Event ID | Log | Description |
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|----------|-----|-------------|
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| 4104 | PowerShell/Operational | Script block logging |
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| 4103 | PowerShell/Operational | Module logging |
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| 800 | PowerShell | Pipeline execution details |
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| 400 | PowerShell | Engine lifecycle (start) |
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| 403 | PowerShell | Engine lifecycle (stop) |
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### Script Block Logging Query
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```powershell
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Get-WinEvent -FilterHashtable @{
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LogName = 'Microsoft-Windows-PowerShell/Operational'
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Id = 4104
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} -MaxEvents 100
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```
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### Event 4104 Properties
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| Index | Field | Description |
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|-------|-------|-------------|
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| 0 | MessageNumber | Block sequence number |
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| 1 | MessageTotal | Total blocks in script |
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| 2 | ScriptBlockText | Actual script content |
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| 3 | ScriptBlockId | Unique script ID |
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| 4 | Path | Script file path |
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## Suspicious PowerShell Patterns
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### Execution Policy Bypass
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```powershell
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powershell -ExecutionPolicy Bypass -File script.ps1
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powershell -ep bypass -nop -w hidden -enc <base64>
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```
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### Common Obfuscation Techniques
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| Technique | Example |
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|-----------|---------|
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| Concatenation | `"Inv"+"oke-Ex"+"pression"` |
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| Variable substitution | `${I`nv`oke-`Ex`pression}` |
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| Encoded commands | `-enc SQBuAHYAbwBrAGUALQA...` |
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| Char array | `[char[]]@(73,69,88) -join ''` |
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## Sigma Detection Rules
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### Suspicious PowerShell Command Line
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```yaml
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title: Suspicious PowerShell Invocation
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logsource:
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product: windows
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category: process_creation
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detection:
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selection:
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CommandLine|contains:
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- '-enc'
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- '-EncodedCommand'
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- 'FromBase64String'
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- 'DownloadString'
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- 'Invoke-Expression'
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condition: selection
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level: high
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```
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## AMSI (Antimalware Scan Interface)
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### AMSI Scan Functions
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```c
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HRESULT AmsiScanBuffer(
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HAMSICONTEXT amsiContext,
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PVOID buffer,
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ULONG length,
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LPCWSTR contentName,
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HAMSISESSION amsiSession,
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AMSI_RESULT *result
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);
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```
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### AMSI Results
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| Value | Meaning |
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|-------|---------|
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| 0 | Clean |
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| 1 | Not Detected |
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| 16384 | Blocked by admin |
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| 32768 | Detected (malware) |
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## Microsoft Defender ATP API
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### Advanced Hunting Query
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```http
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POST https://api.security.microsoft.com/api/advancedqueries/run
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Authorization: Bearer {token}
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{
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"Query": "DeviceProcessEvents | where FileName == 'powershell.exe' | where ProcessCommandLine has_any('encodedcommand','downloadstring','invoke-expression') | project Timestamp, DeviceName, ProcessCommandLine | take 100"
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}
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```
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