security - Securing my web application against malicious input -


i in process of building basic security layer web application. seeking validation of steps taking. current focus xss, not touching databases in post. have done far:

  1. htmlspecialchars() user input
  2. blacklist keywords {"","","text/javascript"} : using preg_replace sub these words "" instead.
  3. output escaping dynamic content.

all of seems trivial security layer. can recommend better strategies ?

your approach simple. htmlspecialchars won't in every context.

here cheat sheet xss , problems there when escaping strings put html.

https://www.owasp.org/index.php/cross-site_scripting_%28xss%29

blacklist has it's drawbacks also. browsers example might parse

text/javascript

and

text/java        script

the same way. new line , spaces removed latter , get's interpreted first one. blacklist isn't going bullet proof method.

best strategy use template library allready handles you. library must know context string going. element value needs different escaping attribute values.


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