Multiple choice technology security

Why is “Black List” input validation considered a weak validation method ?

  1. Because the validation settings are hard coded.

  2. Susceptible to bypass using various forms of character encoding

  3. Because it's difficult to implement a black list filter that also takes into account data sent using the POST method

  4. Because it is typically implemented using regular expressions to match known good data patterns
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Blacklist validation is weak because it tries to block known bad inputs, which attackers can easily bypass using alternative encodings, alternate representations, or obfuscation that the filters do not cover. Distractors incorrectly blame hardcoding, HTTP POST complexity, or confuse blacklists with whitelist-oriented regular expressions.

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