Getting more from your WAF (Sensitive URL Tracking)
I have had the fortune to support a few Imperva installations, alongside other WAF solutions. I would like to illustrate one use for logs available on the Impervaplatform that can be leveraged to augment website trend reports and monitor “exposure” on key URL’s.
If you’re not familiar with the Imperva platform, it is possible (as with other WAF vendor’s products) to build custom policies that must match specific criteria and upon triggering these events can feed data into various syslog feeds. The entire purpose of a WAF is to protect your web application from threats, although some argue this point, so it stands to reason there may be facets of a given web application that are more sensitive than others.
Take for example the check-out page for an online retailer where the customer enters credit card data and confirms their billing information. This location of a web application might benefit from heightened logging under certain conditions by a Web Application Firewall, such as: forced browsing, parameter tampering, XSS, Server Errors, etc. The application may be vulnerable to fraud activities, the business may want to keep a tab on who’s accessing these URLs, or there some other risk criteria than can be measured using this approach.
Traditional webserver logs will provide: client information such as user agent info, username, source ip, method, access URL, response time, response size, and response code. The logged data sits in the access log file on the specific web server by default, but this information is for the entire website.
The Imperva SecureSphere can provide some of the same information: username, IP, Port, user-agent info, accessed URL, response size, response time, etc – but in addition, the Imperva can track whether the session was authenticated, correlated database query (if you have Imperva database protection deployed), SOAP information, security details relevant to the specific policy. The kicker is that this can be sent in a format configured by the admin to a syslog listener in a format supported by web trend tools or SIEM products without engaging professional services.
I’m not advocating the replacement of web server logs for trend analysis, but I am suggesting the deployment of targeted logging for sensitive areas inside an application where this information would prove useful either in a fraud capacity, security monitoring capacity, or even in an end-to-end troubleshooting capacity where a WAF would have visibility beyond traditional network tools from the frontend of a N-tier web application. Deviations in response times, excessive response sizes, and unauthenticated access attempts to sensitive URLs are ideas that come to mind for leveraging the visibility a WAF can bring to the table.