F5 Friday: Eliminating the Blind Spot in Your Data Center Security Strategy

Pop Quiz: In recent weeks, which of the following attack vectors have been successfully used to breach major corporation security? (choose all that apply)

Phishing          Parameter tampering           SQL Injection           DDoS           SlowLoris           Data leakage

If you selected them all, give yourself a cookie because you’re absolutely right. All six of these attacks have successfully been used recently, resulting in breaches across the globe:

That’s no surprise; attacks are ongoing, constantly. They are relentless. Many of them are mass attacks with no specific target in mind, others are more subtle, planned and designed to do serious damage to the victim. Regardless, these breaches all have one thing in common: the breach was preventable. At issue is the reality that attackers today have moved up the stack and are attacking in the data center’s security blind spot: the application layer. Gone are the days of blasting the walls of the data center with packets to take out a site. Data center interconnects have expanded to the point that it’s nearly impossible to disrupt network infrastructure and cause an outage without a highly concerted and distributed effort. It does happen, but it’s more frequently the case that attackers are moving to highly targeted, layer 7 attacks that are far more successful using far fewer resources with a much smaller chance of being discovered.

The security-oriented infrastructure traditionally relied upon to alert on attacks is blind; unable to detect layer 7 attacks because they don’t appear to be attacks. They look just like “normal” users.

The most recent attack, against www.cia.gov, does not appear to be particularly sophisticated. LulzSec described that attack as a simple packet flood, which overwhelms a server with volume. Analysts at F5, which focuses on application security and availability, speculated that it actually was a Slowloris attack, a low-bandwidth technique that ties up server connections by sending partial requests that are never completed. Such an attack can come in under the radar because of the low volume of traffic it generates and because it targets the application layer, Layer 7 in the OSI model, rather than the network layer, Layer 3. [emphasis added]

-- Ongoing storm of cyberattacks is preventable, experts say 

It isn’t the case that organizations don’t have a sound security strategy and matching implementation, it’s that the strategy has a blind spot at the application layer. In fact, it’s been the evolution of network and transport layer security success that’s almost certainly driven attackers to climb higher up the stack in search of new and unanticipated (and often unprotected) avenues of opportunity.


Too often organizations – and specifically developers – hear the words “layer 7” anything and immediately take umbrage at the implication they are failing to address application security. In many situations it is the application that is vulnerable, but far more often it’s not the application – it’s the application platform or protocols that is the source of contention, neither of which a developer has any real control over. Attacks designed to specifically leech off resources – SlowLoris, DDoS, HTTP floods – simply cannot be noticed or prevented by the application itself. Neither are these attacks noticed or prevented by most security infrastructure components because they do not appear to be attacks. In cases where protocol (HTTP) exploitation is leveraged, it is not possible to detect such an attack unless the right information is available in the right place at the right time.

The right place is a strategic point of control. The right time is when the attack begins. The right information is a combination of variables, the context carried with every request that imparts information about the client, network, and server-side status. If a component can see that a particular user is sending data at a rate much slower than their network connection should allow, that tells the component it’s probably an application layer attack that then triggers organizational policies regarding how to deal with such an attack: reject the connection, shield the application, notify an administrator.

Only a component that is positioned properly in the data center, i.e. in a strategic point of control, can properly see all the variables and make such a determination. Only a component that is designed specifically to intercept, inspect and act on data across the entire network and application stack can detect and prevent such attacks from being successfully carried out.

BIG-IP is uniquely positioned – topologically and technologically – to address exactly these kinds of multi-layer attacks. Whether the strategy to redress such attacks is “Inspect and Reject” or “Buffer and Wait”, the implementation using BIG-IP simply makes sense. Because of its position in the network – in front of applications,  between clients and servers – BIG-IP has the visibility into both internal and external variables necessary. With its ability to intercept and inspect and then act upon the variables extracted, BIG-IP is perfectly suited to detecting and preventing attacks that normally wind up in most infrastructure’s blind spot.

This trend is likely to continue, and it’s also likely that additional “blind spots” will appear as consumerization via tablets and mobile devices continues to drive new platforms and protocols into the data center. Preventing attacks from breaching security and claiming victory – whether the intent is to embarrass or to profit – is the goal of a comprehensive organizational security strategy. That requires a comprehensive, i.e. multi-layer, security architecture and implementation. One without any blind spots in which an attacker can sneak up on you and penetrate your defenses.

It’s time to evaluate your security strategy and systems with an eye toward whether such blind spots exist in your data center. And if they do, it’s well past time to do something about it.

More Info on Attack Prevention on DevCentral

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Published Jul 01, 2011
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