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Difference between revisions of "Improper signedness"
From NetSec
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| − | Improper signedness | + | '''Improper signedness''' is caused by allowing signed data when expecting unsigned data. This can cause information disclosure or even code execution in extreme circumstances. Our previous "fixed" code in the "Integer Handled as String" section does still have this problem. It is handled as an integer but the sign is not considered, as "-10" is still a valid integer, this will slip through the (int) cast. Therefore, we need to pass this to the abs() function which takes the absolute value of the data. |
| − | + | ||
Mitigation: | Mitigation: | ||
PHP: | PHP: | ||
| + | {{code|text=<source lang="php"> | ||
<?php | <?php | ||
$id = abs((int)$_GET['id']); | $id = abs((int)$_GET['id']); | ||
@mysql_query("SELECT * FROM user WHERE user_id = " . $id . " LIMIT 1"); | @mysql_query("SELECT * FROM user WHERE user_id = " . $id . " LIMIT 1"); | ||
| − | ?> | + | ?></source>}} |
Auditing: | Auditing: | ||
| Line 16: | Line 16: | ||
Mitigation: | Mitigation: | ||
| − | Rails: | + | Rails:{{code|text=<source lang="ruby"> |
| − | user = User.Find(:conditions => ['id = ?', params[id]] | + | user = User.Find(:conditions => ['id = ?', params[id].abs]) |
| + | </source>}} | ||
Auditing: | Auditing: | ||
[[Category:Secure programming]] | [[Category:Secure programming]] | ||
Revision as of 00:46, 12 May 2013
Improper signedness is caused by allowing signed data when expecting unsigned data. This can cause information disclosure or even code execution in extreme circumstances. Our previous "fixed" code in the "Integer Handled as String" section does still have this problem. It is handled as an integer but the sign is not considered, as "-10" is still a valid integer, this will slip through the (int) cast. Therefore, we need to pass this to the abs() function which takes the absolute value of the data.
Mitigation:
PHP:
<?php
$id = abs((int)$_GET['id']);
@mysql_query("SELECT * FROM user WHERE user_id = " . $id . " LIMIT 1");
?>
|
Auditing:
Unparamaterized Statements:
Examples:
Mitigation:
Rails:
user = User.Find(:conditions => ['id = ?', params[id].abs])
|
Auditing:
