building-detection-rule-with-splunk-spl

building-detection-rule-with-splunk-spl is a skill for Claude Code from 26zl/cybersec-toolkit. It costs 35 tokens per session (2,687 once invoked), scanned A, original, MIT.

A set of instructions for writing Splunk SPL correlation searches, which are queries that connect related security events to detect suspicious activity. The searches create notable events for security analysts to investigate.

In plain words
What is it for?
Use it to build Splunk Enterprise Security detections from log sources, correlate events, and generate analyst alerts.
Why use it?
It helps teams detect patterns that may be missed when looking at individual log entries. It also supports adding context and closing gaps in threat detection.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

Part of the cybersec-toolkit plugin — 197 skills, 2 hooks, 1 MCP server shipped together

Good fit Use it to build Splunk Enterprise Security detections from log sources, correlate events, and generate analyst alerts.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/26zl/cybersec-toolkit/building-detection-rule-with-splunk-spl
Install

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.

Any agent
npx skills add 26zl/cybersec-toolkit --skill building-detection-rule-with-splunk-spl
Clone the repo
git clone --depth 1 https://github.com/26zl/cybersec-toolkit

Made for: Claude Code.

Or install cybersec-toolkit, the plugin that ships this one along with the rest of its 197 skills, 2 hooks, 1 MCP server.

Wrote 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.

agentmods badge for building-detection-rule-with-splunk-spl

README.md
[![agentmods](https://agentmods.dev/badge/skills/26zl/cybersec-toolkit/building-detection-rule-with-splunk-spl/github.svg)](https://agentmods.dev/skills/26zl/cybersec-toolkit/building-detection-rule-with-splunk-spl)
Your own site
<a href="https://agentmods.dev/skills/26zl/cybersec-toolkit/building-detection-rule-with-splunk-spl"><img src="https://agentmods.dev/badge/skills/26zl/cybersec-toolkit/building-detection-rule-with-splunk-spl/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for building-detection-rule-with-splunk-spl

Your own site · 80×15
<a href="https://agentmods.dev/skills/26zl/cybersec-toolkit/building-detection-rule-with-splunk-spl"><img src="https://agentmods.dev/badge/skills/26zl/cybersec-toolkit/building-detection-rule-with-splunk-spl.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 35 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,687 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high YARA Match · line 139
    YARA rule matched a known malware signature (reverse shell, backdoor, ransomware, C2 framework, or info stealer).
    Fix: Remove the malware payload or compromised file entirely. Investigate how it entered the skill and audit all other artifacts for additional indicators of compromise.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00035 $0.02687
Opus 5 $0.00017 $0.01344
Sonnet 5 $0.00007 $0.00537
Haiku 4.5 $0.00003 $0.00269

Measured 8d ago against content hash 104efd62ffd7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

building-detection-rule-with-splunk-spl 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.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/agent.py, scripts/process.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

.claude/skills/building-detection-rule-with-splunk-spl/SKILL.md · 262 lines

How it starts

The opening of the file, as written. The whole thing — 262 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Building Detection Rules with Splunk SPL

Overview

Splunk Search Processing Language (SPL) is the primary query language used in Splunk Enterprise Security for building correlation searches that detect suspicious events and patterns. A well-crafted detection rule aggregates, correlates, and enriches security events to generate actionable notable events for SOC analysts. Enterprise SIEMs on average cover only 21% of MITRE ATT&CK techniques, making skilled SPL rule writing essential for closing detection gaps.

When to Use

  • When deploying or configuring building detection rule with splunk spl capabilities in your environment
  • When establishing security controls aligned to compliance requirements
  • When building or improving security architecture for this domain
  • When conducting security assessments that require this implementation

Prerequisites

  • Splunk Enterprise Security (ES) deployed and configured
  • Access to Splunk Search & Reporting app with appropriate roles
  • Understanding of Common Information Model (CIM) data models
  • Familiarity with MITRE ATT&CK framework techniques
  • Knowledge of the organization's log sources and data flows

Core SPL Detection Rule Patterns

1. Threshold-Based Detection

Detects events exceeding a defined count within a time window.

index=wineventlog sourcetype=WinEventLog:Security EventCode=4625
| stats count as failed_logins dc(TargetUserName) as unique_users by src_ip
| where failed_logins > 10 AND unique_users > 3
| eval severity="high"
| eval description="Brute force attack detected from ".src_ip." with ".failed_logins." failed logins across ".unique_users." accounts"

2. Sequence-Based Detection (Failed Login Followed by Success)

Correlates a sequence of events indicating a successful brute force attack.

index=wineventlog sourcetype=WinEventLog:Security (EventCode=4625 OR EventCode=4624)
| eval login_status=case(EventCode=4625, "failure", EventCode=4624, "success")
| stats count(eval(login_status="failure")) as failures count(eval(login_status="success")) as successes latest(_time) as last_event by src_ip, TargetUserName
| where failures > 5 AND successes > 0
| eval description="Account ".TargetUserName." compromised via brute force from ".src_ip
| eval urgency="critical"

Read the full file on GitHub · 262 lines

Files

What ships with it

7 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.

Changes

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.

  1. 8d ago First seen · 262 lines · 35 tokens per session scan A 104efd62ffd7

Subscribe to this mod's changes

building-detection-rule-with-splunk-spl is a skill published in the GitHub repository 26zl/cybersec-toolkit (54 stars, last pushed today), licensed MIT. It adds 35 tokens to every session and 2,687 once invoked, about $0.0002 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 2026-09-03.

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