Over the past few years attackers have proved adept at compromising even the most secure organizations. A common theme in successful attacks is persistence. Given the complexity of modern software and network environments, if an attacker looks hard enough, or waits long enough, a weakness will become apparent that can allow the attacker to compromise the target. Consequently focusing solely on keeping attackers out of a network is no longer the best strategy to protect an organization from cyber security threats.
The numbers speak volumes: It only takes minutes from the initiation of an attack for an attacker to compromise a system. Once access has been achieved, data can be exfiltrated quickly. Within organizations, it takes in the order of months to discover the compromise, weeks for the breach to be resolved. Clearly attackers have the upper hand. The task of defending networks is becoming more difficult, rather than easier, as perimeters continue to expand through the use of external cloud systems, the phenomena of BYOD, and integrated services with external third parties.
Unfortunately, we cannot turn back the clock and return to more innocent and less complex days. As attackers become more skilled and systems become more complex, it is next to impossible to keep systems completely free from compromise.
I’m not saying that we should give up. In fact, I strongly believe it is still possible to prevent most attacks and -- even when an attack is successful -- it is possible to identify and remediate the breach before harm is incurred. The key is to shift the time frames of an attack, so that the odds are stacked in the defender’s (not the attacker’s) favor.
Australia's Department of Defence found just four mitigation strategies to be successful in preventing 85% of targeted attacks: patching, application whitelisting, restricting administrative privileges, and creating defense-in-depth. These mitigations won’t stop all attacks. Notably, patching won’t help against zero day attacks. However, these strategies will frustrate attackers and force them to expend more time and effort to gain access.
It’s also important to understand that cybercrime is an economic crime. If an attacker finds that a target is too expensive in terms of time, effort, and resources to breach, the attacker will switch attention to an easier target that offers the same rewards at a lower cost. For example, segregating networks so that the attacker cannot easily gain access to confidential information means that attackers have to work harder before they can extract valuable data. The harder and longer attackerd have to work, the better the chances they will leave traces that can be identified.
Network vigilance is another factor that can reduce the time frame from compromise to detection. It is during this period that attackers are able to explore networks and steal resources without hindrance. By identifying abnormal network activity and distinguishing it from normal day-to-day activity, incursions can be detected before they cause harm. Modern SIEM systems allow logging data from IPS systems, firewalls, file servers, and domain servers to be aggregated and analyzed. Not every attacker will generate alerts from the IPS system, but alerts such as users attempting to access files outside of their job role, or at odd times of the day, should prompt security teams to investigate further.
Prioritizing network security alerts requires procedures and practice. Minor alerts should be ignored so that response teams can focus on important issues. Despite the headlines, major breaches are rare events. Security teams may only be faced with such an incident once a decade. However, when an organization is faced with such a scenario, security teams need to be able to respond quickly, effectively, and confidently. This can only happen if people are trained and practiced in responding to such incidents. Working through theoretical exercises to decide how to respond, and practicing response to simulated attacks, should be standard practice in incident planning. By reviewing the results of such practices, improvements can be implemented so that when a major incident does happen, teams know exactly how to respond and react.
In the real world we have to face the fact that, despite our best efforts, we are not going to be able to defend against every attack all of the time. This does not mean that information security is ineffective. On the contrary, security managers are on the front line fighting against the world’s most sophisticated adversaries. But to succeed we need to stack the odds in our favor through better planning; defense strategies that frustrate attackers; and faster spotting, response, and recovery efforts.As Technical Lead within Cisco's TRAC team, Martin Lee researches the latest developments in cybersecurity and delivers expert opinion on how to mitigate emerging threats and related risks. A Certified Information Systems Security Professional (CISSP) and a chartered ... View Full Bio