name: hunting-for-webshell-activity description: Runs a hypothesis-driven threat hunt for web shell deployment (T1505.003) on internet-facing servers by analyzing file creation in web directories, suspicious child-process spawning from web server processes, and anomalous HTTP request patterns. Use when hunting for web shells after a public-facing app compromise, when EDR/SIEM alerts fire on webserver process anomalies, or during incident response on internet-facing infrastructure. domain: cybersecurity subdomain: threat-hunting tags:

• threat-hunting
• mitre-attack
• webshell
• persistence
• web-server
• t1505
• proactive-detection

version: '1.0' author: mahipal license: Apache-2.0 d3fend_techniques:

• Executable Denylisting
• Execution Isolation
• File Metadata Consistency Validation
• Restore Access
• Process Termination

nist_csf:

• DE.CM-01
• DE.AE-02
• DE.AE-07
• ID.RA-05

mitre_attack:

• T1046
• T1057
• T1082
• T1083
• T1547

Hunting For Webshell Activity

When to Use

• When proactively hunting for indicators of hunting for webshell activity 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

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

Tools & Systems

Common Scenarios

1. Scenario 1: China Chopper web shell via IIS vulnerability
2. Scenario 2: ASPXSpy through vulnerable upload
3. Scenario 3: PHP shell hidden in image file
4. Scenario 4: JSP shell via Tomcat manager console

Output Format

Hunt ID: TH-HUNTIN-[DATE]-[SEQ]
Technique: T1505.003
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]