fix(csv): prevent formula injection in CSV exports (CWE-1236) - #926
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When exporting benchmark results to CSV, hyperfine writes the command string and parameter values verbatim. Spreadsheet applications like Excel, LibreOffice Calc, and Google Sheets interpret cells beginning with '=', '+', '-', '@', tab, or carriage return as formulas, which can lead to formula injection (CWE-1236) when parameter values come from external input. This change adds a sanitize_csv_value() helper that prefixes such values with a single quote to force literal text interpretation, and applies it to both the command field and all parameter_* columns. Fixes sharkdp#915 Signed-off-by: Nikolas Sapa <84yk8btb9f@privaterelay.appleid.com>
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Problem
When exporting benchmark results to CSV, hyperfine writes the command string and parameter values verbatim into CSV cells. Spreadsheet applications (Excel, LibreOffice Calc, Google Sheets) interpret cells beginning with
=,+,-,@, tab, or carriage return as formulas, which can lead to formula injection (CWE-1236) when parameter values come from external input.For example,
--parameter-list payload '=1+1'exported to CSV contains the literal, unescaped text=1+1, which is evaluated as a live formula when the file is opened in a spreadsheet.Fix
Add a
sanitize_csv_value()helper that prefixes values beginning with formula-triggering characters with a single quote ('), forcing spreadsheet applications to display them as literal text. The helper is applied to both thecommandfield and allparameter_*columns.This is the standard mitigation for CWE-1236 and does not affect values that don't begin with dangerous characters. Numeric fields (mean, stddev, etc.) are unaffected since they are serialized from
f64values which cannot produce formula-interpretable strings.Testing
Added two new tests:
test_csv_formula_injection_sanitization: Integration test that verifies a parameter value of=1+1is properly escaped in the CSV output as'=1+1.test_sanitize_csv_value: Unit test covering all six dangerous prefixes (=,+,-,@,\t,\r) and several safe values that should pass through unchanged.All existing tests pass (3 unit + 39 integration).