analyzing-prefetch-files-for-execution-history

analyzing-prefetch-files-for-execution-history is a skill for Claude Code, Codex from xalgorix/xalgorix. It costs 34 tokens per session (3,606 once invoked), scanned A, original, Apache-2.0.

A guide to reading Windows Prefetch files, which record information about programs that may have run, including run times, counts, and files they loaded. It also explains how to account for systems where Prefetch is disabled or unavailable.

In plain words
What is it for?
Use it during malware or incident investigations to confirm suspicious program use, identify unauthorized tools, and correlate execution with other forensic records.
Why use it?
It helps investigators build a program-execution timeline without treating missing Prefetch files as proof that nothing ran. Findings can be checked against other Windows evidence.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it during malware or incident investigations to confirm suspicious program use, identify unauthorized tools, and correlate execution with other forensic records.

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Install with agentmods
npx agentmods add skills/xalgorix/xalgorix/analyzing-prefetch-files-for-execution-history
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 xalgorix/xalgorix --skill analyzing-prefetch-files-for-execution-history
Clone the repo
git clone --depth 1 https://github.com/xalgorix/xalgorix

Made for: Claude Code, Codex.

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 analyzing-prefetch-files-for-execution-history

README.md
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Your own site
<a href="https://agentmods.dev/skills/xalgorix/xalgorix/analyzing-prefetch-files-for-execution-history"><img src="https://agentmods.dev/badge/skills/xalgorix/xalgorix/analyzing-prefetch-files-for-execution-history/github.svg" alt="Measured on agentmods" height="20"></a>

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Your own site · 80×15
<a href="https://agentmods.dev/skills/xalgorix/xalgorix/analyzing-prefetch-files-for-execution-history"><img src="https://agentmods.dev/badge/skills/xalgorix/xalgorix/analyzing-prefetch-files-for-execution-history.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,606 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: 2 findings, 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 194
    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.
  • high YARA Match · line 194
    YARA rule matched a hack tool or exploit indicator (offensive tools, reconnaissance, privilege escalation, or exploit frameworks).
    Fix: Remove offensive tool references and exploit code. Legitimate agent skills should not contain penetration testing tools, exploit frameworks, or reconnaissance utilities.
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 $0.00034 $0.03606
Opus 5 $0.00017 $0.01803
Sonnet 5 $0.00007 $0.00721
Haiku 4.5 $0.00003 $0.00361

Measured 8d ago against content hash 7d521b76ebc3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

analyzing-prefetch-files-for-execution-history 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.

internal/tools/skills/data/digital-forensics/analyzing-prefetch-files-for-execution-history/SKILL.md · 332 lines

How it starts

The opening of the file, as written. The whole thing — 332 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Analyzing Prefetch Files for Execution History

When to Use

  • When determining which programs were executed on a Windows system and when
  • During malware investigations to confirm execution of suspicious binaries
  • For establishing a timeline of application usage during an incident
  • When correlating program execution with other forensic artifacts
  • To identify anti-forensic tools or unauthorized software that was run

Detection Gaps & Validation

  • Prefetch disabled or absent != no execution: Prefetch is off by default on Windows Server, and on SSD systems EnablePrefetcher is often set to 0. An empty or sparse C:\Windows\Prefetch\ does not mean nothing ran - confirm the policy at HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters before concluding "no execution," then pivot to Amcache/ShimCache/SRUM/Event Logs.
  • Most-missed details inside the .pf: parse the up-to-8 last-run timestamps (not just the most recent), the run count, and the referenced-file list (loaded DLLs, opened data files). The embedded path hash matters: a hash that doesn't match the on-disk path means the binary ran from a different location (USB, deleted folder) than where it now sits.
  • Anti-forensics that defeats this analysis: attackers delete individual .pf files or clear the folder - a present executable with no Prefetch, or a folder with fewer files than an active system accumulates, is itself suspicious. Recover deleted .pf from $MFT/unallocated and Volume Shadow Copies, and corroborate the gap with USN delete events.
  • Validate with a second source: Prefetch proves a binary executed at least once - confirm the what/when against Amcache (Amcache.hve), ShimCache (AppCompatCache), SRUM, Security 4688 / Sysmon 1 process-creation events, and the on-disk file's $MFT times before attributing a run to a user or time.
  • Interpretation pitfalls (false positives): the last-run time is when the prefetch was written (~10s after launch start, with historical caveats), run count can reset, and renamed malware (e.g. svchost.exe from %TEMP%) hides behind a trusted name - check the path hash and referenced files, not the filename. Confirm system timezone and clock skew.

Read the full file on GitHub · 332 lines

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 · 332 lines · 34 tokens per session scan A 7d521b76ebc3

Subscribe to this mod's changes

analyzing-prefetch-files-for-execution-history is a skill published in the GitHub repository xalgorix/xalgorix (975 stars, last pushed 2d ago), licensed Apache-2.0. It adds 34 tokens to every session and 3,606 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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