Enterprise Endpoint Threat Hunting: Sigma Rules, Memory Forensics & IOC Detection

Modern Advanced Persistent Threats (APTs) and sophisticated ransomware operators frequently bypass traditional signature-based antivirus solutions by executing in-memory code injection, LOLBins (Living Off the Land Binaries), and unbacked execution threads. Proactive Endpoint Threat Hunting combining generic Sigma rules with deep memory forensics is essential for rapid incident containment.

Enterprise Endpoint Threat Hunting and Sigma Detection Architecture — Fig 1: 4-Stage Hunting Pipeline: Telemetry Ingestion, Sigma Engine, Memory Carving & C2 Triage.

1. Sigma Rules: The Universal Detection Standard

Sigma is an open-source, vendor-agnostic signature format allowing security analysts to describe detection logic in standardized YAML. Sigma rules can be dynamically compiled into native SIEM queries (such as Grafana Loki LogQL, Splunk SPL, or Elasticsearch Lucene):

# Sample Sigma Rule: Suspicious PowerShell Process Hollowing
title: Suspicious Process Injection via Encoded PowerShell
status: experimental
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\powershell.exe'
        CommandLine|contains:
            - '-enc '
            - '-EncodedCommand '
            - 'FromBase64String'
    condition: selection
level: high
tags:
    - attack.execution
    - attack.t1059.001

2. Memory Forensics with Volatility 3

When an adversary injects malicious shellcode directly into legitimate Windows processes (e.g. svchost.exe or explorer.exe), raw memory triage via Volatility 3 reveals unbacked Virtual Address Descriptors (VAD):

windows.malfind: Scans memory regions with Page Execute-Read-Write (PAGE_EXECUTE_READWRITE) permissions that lack associated file mappings on disk.
windows.pslist & psscan: Identifies unlinked processes hidden from the Windows Kernel Process Active Process Links list (DKOM attacks).
windows.netscan: Carves active TCP sockets and ephemeral listeners communicating with external Command & Control (C2) servers.