This script is possibly vulnerable to XPath Injection attacks. XPath Injection is an attack technique used to exploit web sites that construct XPath queries from user-supplied input. XPath Injection attacks occur when a web site uses user-supplied information to construct an XPath query for XML data. By sending intentionally malformed information into the web site, an attacker can find out how the XML data is structured, or access data that they may not normally have access to.

An unauthenticated attacker may extract a complete XML document using XPath querying. This may compromise the integrity of your database and expose sensitive information.

Your script should filter metacharacters from user input.

There are numerous freely available tools to exploit SQL injection vulnerabilities. This is a complex area with many dependencies; however, it should be noted that the numerous resources available in this area have raised both attacker awareness of the issues and their ability to discover and leverage them. SQL injection is one of the most common web application vulnerabilities.

1. See the remedy for solution.
2. If you are not using a database access layer (DAL), consider using one. This will help you centralize the issue. You can also use ORM (object relational mapping). Most of the ORM systems use only parameterized queries and this can solve the whole SQL injection problem.
3. Locate all of the dynamically generated SQL queries and convert them to parameterized queries. (If you decide to use a DAL/ORM, change all legacy code to use these new libraries.)
4. Use your weblogs and application logs to see if there were any previous but undetected attacks to this resource.