Tuesday, June 30, 2009

Vulnerability Scanning and Clouds/SaaS/IaaS/PaaS

Here is a very fun post called “Vulnerability Scanning and Clouds: An Attempt to Move the Dialog On…” I loved it so much, I will just quote my favorite parts here with a few comments. It starts like this:

“Much has been said about public IaaS providers that expressly forbid customers from running network scans against their cloud hosted infrastructure.”

In other words, they host your server, but you cannot check it for vulnerabilities at all.

“As has been noted before, a blanket ban on legitimate scanning activity by customers of their own infrastructure (whether outsourced or not) undermines security assurance processes and can make regulatory compliance impossible; e.g. PCI DSS mandates network vulnerability scanning as a control”

Use PaaS – lose PCI DSS compliance status. Nice! Sadly, the above interpretation is correct as, I suspect, the IaaS/PaaS provider is not allowed to scan your boxes either. So, nobody does. And then you get 0wned.

Next the post highlights that the fact that vulnerability management challenges are magnified by using PaaS/IaaS. For example:

Scanning may trigger automated or manual actions by the provider. A common automated response from a provider is to apply traffic shaping to slow down the scan, or simply block the client IP address via an ACL update.  This can lead to false negatives; i.e. vulnerabilities present are not discovered as the scanner IP was automagically identified as a noisy vulnerability scanner and auto-throttled/blocked.”

He then highlight somewhat obvious, but still key point:

“Even if spinning up copies of “known good/secure” virtual machine (VM), you still need to scan them.”


“So the bad guys get to scan because they don’t care and yet the customer, who wants to do the “right thing”, is not allowed to.  Is that rational?”

The solution is “easy” – if you need scanning (and everybody does!) and you PaaS doesn’t allow it, don’t use that PaaS. But is this a solution? The post the  suggests “ScanAuth API” which will allow controlled scanning:

Something like an “ScanAuth” (Scan Authorize) API call offered by cloud providers that a customer can call with parameters for conveying source IP address(es) that will perform the scanning, and optionally a subset of their Cloud hosted IP addresses, scan start time and/or duration. This request would be signed by the customers API secret/private key as per other privileged API calls.”

I am not sure about you, but this sounds like an awesome idea! The original post calls for the start of discussion, and I am happy to continue it. Finally, as of today, I don’t think we can rely on “other security tools”  (software assurance, secure coding, etc) to supplant the need for vulnerability scanning. if you deploy an OS in the cloud, you’d need to scan it.

BTW, similarly to network vulnerability scanning, the situation is actually worse for web app scanning? If you have “doubts” about your blog provider, can you hit it with Qualys WAS?

Dr Anton Chuvakin