Webapp Hunting For Supply Chain Compromise

---
name: webapp-hunting-for-supply-chain-compromise
description: Hunt for supply chain compromise indicators including trojanized software updates, compromised dependencies, unauthorized code modifications, and tampered build artifacts.
domain: webapp
category: threat-intelligence
hide: true
license: Apache-2.0
metadata:
  manifest_entry: src/corpus/webapp-hunting-for-supply-chain-compromise/SKILL.md
---
# 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

1. **Formulate Hypothesis**: Define a testable hypothesis based on threat intelligence or ATT&CK gap analysis.
2. **Identify Data Sources**: Determine which logs and telemetry are needed to validate or refute the hypothesis.
3. **Execute Queries**: Run detection queries against SIEM and EDR platforms to collect relevant events.
4. **Analyze Results**: Examine query results for anomalies, correlating across multiple data sources.
5. **Validate Findings**: Distinguish true positives from false positives through contextual analysis.
6. **Correlate Activity**: Link findings to broader attack chains and threat actor TTPs.
7. **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

1. **Scenario 1**: SolarWinds-style update mechanism compromise
2. **Scenario 2**: Compromised npm/PyPI package with backdoor
3. **Scenario 3**: Tampered build server deploying malicious artifacts
4. **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]
```