detecting-evasion-techniques-in-endpoint-logs

Files (8)

• LICENSE
• SKILL.md
• template.md · assets/
• api-reference.md · references/
• standards.md · references/
• workflows.md · references/
• agent.py · scripts/
• process.py · scripts/

SKILL.md (first lines)

# Detecting Evasion Techniques in Endpoint Logs

## When to Use

Use this skill when:
- Hunting for adversary defense evasion techniques (MITRE ATT&CK TA0005) in endpoint telemetry
- Building detection rules for common evasion methods (process injection, timestomping, log clearing)
- Investigating incidents where adversaries disabled or bypassed security tools
- Analyzing endpoint logs for indicators of living-off-the-land binary (LOLBin) abuse

**Do not use** this skill for network-level evasion (use network traffic analysis) or for malware reverse engineering.

## Prerequisites

- Sysmon installed and configured with comprehensive logging rules (SwiftOnSecurity or Olaf Hartong config)
- Windows Security Event Log with advanced audit policy enabled
- EDR telemetry (CrowdStrike, SentinelOne, Microsoft Defender for Endpoint)
- SIEM platform for log correlation (Splunk, Elastic, Sentinel)
- MITRE ATT&CK Enterprise matrix for technique reference

## Workflow

### Step 1: Detect Log Tampering (T1070)

**Windows Event Log clearing (T1070.001)**:
```
# Sysmon Event ID 1 (Process Create) for wevtutil
EventID: 1
CommandLine contains: "wevtutil cl" OR "wevtutil clear-log"

# Security Event ID 1102 - Audit log was cleared
EventID: 1102
Source: Microsoft-Windows-Eventlog

# System Event ID 104 - Event log was cleared
EventID: 104

# PowerShell log clearing
EventID: 1 (Sysmon)
CommandLine contains: "Clear-EventLog" OR "Remove-EventLog"

# Splunk query:
index=windows (EventCode=1102 OR EventCode=104)
  OR (EventCode=1 CommandLine="*wevtutil*cl*")
  OR (EventCode=1 CommandLine="*Clear-EventLog*")
| table _time host user CommandLine EventCode
```

**Timestomping (T1070.006)**:
```
# Sysmon Event ID 2 - File creation time changed
EventID: 2
# Look for creation times set far in the past on recently-written files
# Correlate with Event ID 11 (FileCreate) - if FileCreate is recent but
# creation time in Event ID 2 is old, timestomping is likely

# MDE Advanced Hunting (KQL):
DeviceFileEvents
| where ActionType == "FileTimestampModified"
| where Timestamp > ago(7d)
| extend TimeDiff = datetime_diff('day', Timestamp, ReportedFileCreationTime)
| where TimeDiff > 30
| project Timestamp, DeviceName, FileName, FolderPath,
    ReportedFileCreationTime, InitiatingProcessFileName
```

### Step 2: Detect Process Injection (T1055)

```
# Sysmon Event ID 8 - CreateRemoteThread
EventID: 8
# Alert when source process is unusual (not system processes)
# Filter out known legitimate: antivirus, debugging tools
SourceImage NOT IN ("C:\Windows\System32\csrss.exe",
                     "C:\Windows\System32\lsass.exe")

# Sysmon Event ID 10 - ProcessAccess with suspicious access masks
EventID: 10
GrantedAccess contains: "0x1F0FFF" OR "0x1FFFFF" OR "0x001F0FFF"
# PROCESS_ALL_ACCESS = 0x1F0FFF (common in injection)
# Filter legitimate: AV accessing all processes

# Sysmon Event ID 25 - Process Tampering
EventID: 25
Type: "Image is replaced"  # Process hollowing indicator

# Splunk detection:
index=sysmon EventCode=8
| where NOT match(SourceImage, "(?i)(csrss|svchost|MsMpEng|defender)")
| stats count by SourceImage TargetImage host
| where count < 5
| sort - count
```

### Step 3: Detect Security Tool Disabling (T1562)

```
# Service stopped events for security services
EventID: 7045 (new service) OR 7036 (service state change)
ServiceName IN ("WinDefend", "Sense", "CrowdStrike Falcon Sensor",
                 "SentinelAgent", "csagent", "MBAMService")

# Sysmon Event ID 1 - Processes that disable Defender
CommandLine contains: "Set-MpPreference -DisableRealtimeMonitoring"
  OR "sc stop WinDefend"
  OR "sc config WinDefend start= disabled"
  OR "net stop" AND ("windefend" OR "sense" OR "csagent")

# Registry modification to disable security features
# Sysmon Event ID 13 - Registry value set
TargetObject contains: "DisableAntiSpyware"
  OR "DisableRealtimeMonitoring"
  OR "DisableBehaviorMonitoring"
Details: "DWORD (0x00000001)"

# MDE KQL:
DeviceRegistryEvents
| where RegistryValueName in ("DisableAntiSpyware", "DisableRealtimeMonitoring")
| where RegistryValueData == "1"
| project Timestamp, DeviceName, RegistryKey, InitiatingProcessFileName

From mukul975/Anthropic-Cybersecurity-Skills, Apache-2.0.

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