miscmedium

Flask Calculator

duckerz

Task: exploit a Flask calculator that uses eval() with a character filter blocking ASCII letters and underscores. Solution: bypass the filter using fullwidth Unicode characters for eval (which Python normalizes to built-in names) and octal escape sequences to construct arbitrary strings.

$ ls tags/ techniques/
unicode_normalization_bypasseval_injectionfullwidth_charactersoctal_escape_sequences

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