Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add willwebster5/agent-skills --skill behavioral-detectionsgit clone --depth 1 https://github.com/willwebster5/agent-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/willwebster5/agent-skills/behavioral-detections)<a href="https://agentmods.dev/skills/willwebster5/agent-skills/behavioral-detections"><img src="https://agentmods.dev/badge/skills/willwebster5/agent-skills/behavioral-detections.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00061 | $0.01886 |
| Opus 5 | $0.00030 | $0.00943 |
| Sonnet 5 | $0.00012 | $0.00377 |
| Haiku 4.5 | $0.00006 | $0.00189 |
Grade A, and why
behavioral-detections scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 235 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Behavioral Detection Engineering
Design and implement behavioral detection rules that identify attack patterns across multiple events using CrowdStrike NG-SIEM's correlate() function.
When to Use This Skill
Use this skill when you need to:
- Design attack chain detections (recon → escalation → persistence)
- Build behavioral rules that span multiple events over time
- Create compound detections from multiple rule triggers
- Correlate events across different data sources (AWS + EntraID + CrowdStrike)
- Detect multi-stage attacks that single-event rules would miss
Quick Start: Your First Behavioral Rule
// Detect failed logins followed by successful access
correlate(
FailedLogins: {
event.outcome="failure"
event.action=/UserLogon|Sign-in/
},
SuccessfulLogin: {
event.outcome="success"
event.action=/UserLogon|Sign-in/
| user.email <=> FailedLogins.user.email
},
sequence=true,
within=30m,
globalConstraints=[user.email]
)
| table([SuccessfulLogin.user.email, FailedLogins.source.ip])
Core Concepts
Behavioral vs Correlation Rules
| Type | Function | Use Case |
|---|---|---|
| Correlation Rule | Single-event threshold | "Alert on 50+ failed logins" |
| Behavioral Rule | Multi-event pattern via correlate() |
"Alert on failed logins FOLLOWED BY success" |
correlate() Key Components
-
Named Queries: Each event pattern has a unique name
QueryName: { filter_expression } -
Link Operator
<=>: Correlates fields between queries| user.email <=> OtherQuery.user.email -
Sequence: Enforce chronological order
sequence=true // Events must occur in order -
Time Window: Constrain event timing
within=1h // All events within 1 hour -
Global Constraints: Fields all events must share
globalConstraints=[user.email, cloud.account.id]
Attack Pattern Design Workflow
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 235 lines · 61 tokens per session scan A 2bb9c569ac7e
behavioral-detections is a skill published in the GitHub repository willwebster5/agent-skills (12 stars, last pushed 4mo ago), licensed MIT. It adds 61 tokens to every session and 1,886 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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