xalgord Hunting For Supply Chain Compromise
When to Use
- When proactively hunting for indicators of hunting for supply chain compromise in the environment
- After threat intelligence indicates active campaigns using these techniques
- During incident response to scope compromise related to these techniques
- When EDR or SIEM alerts trigger on related indicators
- During periodic security assessments and purple team exercises
Detection Gaps & Validation
- Signed-but-trojanized updates evade signature checks: SolarWinds-style backdoors pass Authenticode validation — hunt behavioral deviation (a signed app suddenly opening new C2 connections, Sysmon EID 3; spawning script interpreters, EID 1) rather than signature status.
- Wrong scope: dependency compromise (npm/PyPI
postinstall, typosquats) executes at build/install time on developer and CI hosts, not prod endpoints — extend the hunt to build agents. - Trusting attacker-controlled hashes: verifying against the vendor's published hash fails when the vendor is the compromise — compare against an independently captured prior known-good.
- DLL side-loading: a legit signed EXE + malicious DLL in the same directory is a common delivery — watch EID 7 ImageLoad of unsigned/unexpected modules from app dirs.
- Validate: stage a benign "updated" binary that makes a new outbound connection; confirm EID 7 (image load) / EID 3 anomaly fires.
- FP tuning: baseline normal updater network destinations and expected signed-module load paths.
Prerequisites
- EDR platform with process and network telemetry (CrowdStrike, MDE, SentinelOne)
- SIEM with relevant log data ingested (Splunk, Elastic, Sentinel)
- Sysmon deployed with comprehensive configuration
- Windows Security Event Log forwarding enabled
- Threat intelligence feeds for IOC correlation
Workflow
- Formulate Hypothesis: Define a testable hypothesis based on threat intelligence or ATT&CK gap analysis.
- Identify Data Sources: Determine which logs and telemetry are needed to validate or refute the hypothesis.
- Execute Queries: Run detection queries against SIEM and EDR platforms to collect relevant events.
- Analyze Results: Examine query results for anomalies, correlating across multiple data sources.
- Validate Findings: Distinguish true positives from false positives through contextual analysis.
- Correlate Activity: Link findings to broader attack chains and threat actor TTPs.
- Document and Report: Record findings, update detection rules, and recommend response actions.
Key Concepts
| Concept | Description |
|---|---|
| T1195.001 | Compromise Software Dependencies |
| T1195.002 | Compromise Software Supply Chain |
| T1199 | Trusted Relationship |
Tools & Systems
| Tool | Purpose |
|---|---|
| CrowdStrike Falcon | EDR telemetry and threat detection |
| Microsoft Defender for Endpoint | Advanced hunting with KQL |
| Splunk Enterprise | SIEM log analysis with SPL queries |
| Elastic Security | Detection rules and investigation timeline |
| Sysmon | Detailed Windows event monitoring |
| Velociraptor | Endpoint artifact collection and hunting |
| Sigma Rules | Cross-platform detection rule format |
Common Scenarios
- Scenario 1: SolarWinds-style update mechanism compromise
- Scenario 2: Compromised npm/PyPI package with backdoor
- Scenario 3: Tampered build server deploying malicious artifacts
- Scenario 4: Vendor VPN software update delivering malware
Output Format
Hunt ID: TH-HUNTIN-[DATE]-[SEQ]
Technique: T1195.001
Host: [Hostname]
User: [Account context]
Evidence: [Log entries, process trees, network data]
Risk Level: [Critical/High/Medium/Low]
Confidence: [High/Medium/Low]
Recommended Action: [Containment, investigation, monitoring]