Central to the recent Target data breach lawsuit settlement was the idea that cyber attacks are mechanistic and follow a prescribed course or chain of events. The judge hearing the case ruled that Target is liable for not mounting an adequate defense against the 2013 cyber attack that exposed some 40 million customer debit and credit card accounts. Unfortunately, the ruling also may have serious repercussions for many of us in the security profession.

In my opinion, Judge Paul A. Magnuson’s ruling is dangerously flawed and a gross misrepresentation of how attackers operate; it ignores the fact that the breach was conducted by actual people. Preventing one event in a supposed chain will not stop a breach. Attackers will simply find another way to achieve their goal. The challenge is to identify that a targeted attack is under way and then rip the attackers out of the network.

Here are three examples of where the ruling went wrong:
Misunderstanding #1: Targeted attacks are not linear processes
The data breach lawsuit argued:
“The fundamental premise of kill chain security is that hackers must proceed through seven steps to plan and execute an attack. While the hackers must complete all of these steps to execute a successful attack, the company has to stop the hackers from completing just one of these steps to prevent completion of the attack and data loss…”

This is old-school, breach prevention thinking. While it is useful to categorize the different phases of an attack, assuming linearity is wrong.

The fact is that taking additional preventive actions would not necessarily have neutralized the Target attack. For example, the court points to a flaw of not blocking uploads to servers with a Russian domain. Taking this precaution would not have saved Target from the breach. The attacker could have set up US-based servers through Amazon Web Services at minimal cost. This is a good example of a dynamic, human-led attack, rather than something that is static.

Additionally, the legal contention that since the FireEye malware detection system and Symantec endpoint protection system identified suspicious activity, Target should have caught it and taken immediate action. Would detecting and removing specific malware have prevented the attack? No! It would only have neutralized one step. This was months after the attackers infiltrated the network. At this point, the attackers had numerous footholds inside Target. They could have easily chosen some other exfiltration tactics not detectable by Symantec or FireEye.

Listing the weak links compromised in an attack is easy ex post facto. But there were probably hundreds of other steps that the attackers planned, attempted and failed, taking instead the actual steps that were eventually successful. The attack was not an act of prescribed step-by-step mechanization.

Misunderstanding #2: Breaches can be prevented
The simple reality is that targeted breaches cannot be prevented in advance. The phrase “entirely preventable data breach” was stated as fact in the legal case, but it is a fiction. Unfortunately, much of the security industry suffers the same delusion.

When analyzing a data breach or a penetration test scenario, we always find weak points that can and should be strengthened. We also know that penetration tests always succeed, because they are run by well-trained, sophisticated attackers who are able to circumvent whatever specific security controls are in use given enough time and incentive. We simply need to accept as an industry that there will always be a way in to a network, and then a foothold can be established. There is no single step that can be taken in advance that would eliminate all breaches.

Misunderstanding #3: Breaches are identified by the malware
It’s clear that once the targeted attacker is through the perimeter, all preventative efforts become irrelevant. By definition, prevention systems that look for malware and other intrusions have only one chance to detect the “technical artifact” that they are built to identify, and if they miss that chance then the attacker gains a foothold in the network. But malware is generally only a small part of an active breach and may not be involved at all. And “intrusion” is only the first moment of a breach, whereas actual damage can take months to materialize.

Assuming that not all intrusions can be detected, the defender must then focus on the large volume of reconnaissance and lateral movement inside the breached network – the active part of the breach. This is the time after the initial intrusion and the resulting theft or damage – and usually lasts for months.

While the initial breach to Target’s network could not have been prevented, the attackers’ movement within the network could have been detected as the intruders explored the network and established points of control. In order to detect targeted attackers during this active attack phase, however, we as an industry needs to change the way we think about breach detection.