Web services are vulnerable to several attacks. These attacks can lead to information leakage and further aid in remote command execution. By using WSDL an attacker can determine an access point and available interfaces for web services. These interfaces or methods take inputs using SOAP over HTTP/HTTPS. If these inputs are not defended well at the source code level, they can be compromised and exploited. ModSecurity operates as an Apache Web server module, ideal for defending web services against attacks that also include malicious /POST variable/content. This paper describes techniques to defend your web services layer using mod_security.
Some interesting resources on same topic.