Poor code quality leads to unpredictable behavior. From a user's perspective that often manifests itself as poor usability. For an attacker it provides an opportunity to stress the system in unexpected ways.
...
var file:File = new File(directoryName + "\\" + fileName);
...
...
FileStream f = File.Create(directoryName + "\\" + fileName);
...
...
File file = new File(directoryName + "\\" + fileName);
...
...
os.open(directoryName + "\\" + fileName);
...
<script> tag.
...
public String tagProcessor(String tag){
if (tag.toUpperCase().equals("SCRIPT")){
return null;
}
//does not contain SCRIPT tag, keep processing input
...
}
...
Example 1 is that java.lang.String.toUpperCase() when used without a locale uses the rules of the default locale. Using the Turkish locale "title".toUpperCase() returns "T\u0130TLE", where "\u0130" is the "LATIN CAPITAL LETTER I WITH DOT ABOVE" character. This can lead to unexpected results, such as in Example 1 where this will prevent the word "script" from being caught by this validation, potentially leading to a Cross-Site Scripting vulnerability.
...
import java.sql.PreparedStatement;
import com.sap.sql.NativeSQLAccess;
String mssOnlyStmt = "...";
// variant 1
PreparedStatement ps =
NativeSQLAccess.prepareNativeStatement(
conn, mssOnlyStmt);
. . .
// variant 2
Statement stmt =
NativeSQLAccess.createNativeStatement(conn);
int result = stmt.execute(mssOnlyStmt);
. . .
// variant 3
CallableStatement cs =
NativeSQLAccess.prepareNativeCall(
conn, mssOnlyStmt);
. . .