Difference between revisions of "Input Validation"

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Check [[:Category:Input Validation]] for contents
Check [[:Category:Input Validation]] for contents
[[Category: Control]]
[[Category:FIXME|This says it's a control, but it's in the principles TOC. Which is it?]]
[[Category:FIXME|This says it's a control, but it's in the principles TOC. Which is it?]]

Revision as of 14:13, 19 October 2008

This is a control. To view all control, please see the Control Category page.

This article is a stub. You can help OWASP by expanding it or discussing it on its Talk page.

ASDR Table of Contents

Using black and/or white lists which defines valid input data. Such approach is more accurate and provides better risk analysis, when there is need of modification of the lists.

E.g. When we expect digits as an input, then we should perform accurate input data validation.

#include <stdio.h>
#include <ctype.h>
#include <string.h>

int main(int argc, char **argv)
       char a[256];
       strncpy(a, argv[1], sizeof(a)-1);

       int b=0;

       for(b=0; b<strlen(a); b++) {
               if(isdigit((int)a[b])) printf("%c", a[b]);

       return 0;

In PHP for input data validation we may use e.g. preg_match() function:

  $clean = array();
  if (preg_match("/^[0-9]+:[X-Z]+$/D", $_GET['var'])) {
     $clean['var'] = $_GET['var'];

For special attention deserves modifier "/D", which additionally protects against HTTP Response Splitting type of attacks.

Avoid using of environment variables if the attacker may alter their values.

Check Category:Input Validation for contents