These rare but high-priority vulnerabilities, including a recent example in Adobe Flash that was being actively exploited, can inflict serious harm if they become known to attackers because no patch exists to immediately eliminate the threat. Earlier this year, a particularly prolific and urgent zero-day outbreak garnered major headlines because it placed tens thousands of web applications at risk.
In 2016, the Trustwave SpiderLabs team tracked nine zero-day vulnerabilities exploited in the wild, five of which targeted Flash, three of which targeted Microsoft Internet Explorer and one of which targeted Microsoft Silverlight. The team also unearthed a zero-day for sale in the cybercriminal underground, proving these software holes are no longer solely the domain of the deep-pocketed advanced persistent threat (APT) groups and nation-states.
With the market for zero-days flush and reports of huge government stockpiles worrying some observers over potential leaks, now is the time to solidify your strategy for addressing them.
1) Manage Your Assets
Depending on the software you are running, not every instance of a zero-day will affect you. You should review what software is installed in your environment, uninstall any software that is no longer needed and disable any features that are not used. This will decrease your potential attack surface and may eliminate the impact of certain 0-days that target the removed software or the disabled features.
2) Patch Your Software
While a patch won’t do you any good if a zero-day exploit is impacting your organization, you will want to ensure all available fixes have been applied because the 0-day may rely on other components to complete its attack. For example, a local privilege-escalation zero-day may exist, but if you are patched against a remote-code execution vulnerability that is used in tandem with the zero-day, you’ll likely avoid major harm. In addition, remember that once the zero-day receives a fix, attackers will still exploit it – and those that are tardy to the patch party may be in for a rude surprise.
3) Break the Attack Kill Chain
A successful compromise involves many phases, which is good news for you because it gives opportunities to thwart an incursion before it can inflict maximum damage. You can increase your odds of doing this by deploying a full stack of intelligent security products , using generic, behavior and heuristic-based approaches to threat visibility, monitoring and detection. Thinking of your security in an offensive way – where you proactively look for potential breaches – will help prevent your zero-day adversaries from setting up shop in your environment for an extended period.
4) Keep Your Employees Informed
Molding perfectly disciplined behavior by employees to avoid security mishaps – like clicking on a link they shouldn’t which triggers a zero-day – is impossible, but relying on the wits of your workers is still important, especially if the security products you have in place are not providing the proactive defense you need to address today’s threats. Security awareness programs don’t need to be agonizingly boring – effective ones get creative and use stories to motivate the troops.
What about the non-zero-day vulnerabilities?
0-day vulnerabilities attract a disproportionate amount of attention because of the perception that organizations are left wide open to attack, with no way to stop it. It is this fear of the unknown that drives paranoia, but a reality check is in order.
In most breach cases involving vulnerabilities, attackers exploited flaws that had been patched for weeks, months or even years. Keeping this in mind, you should incorporate a security testing program that combines automated vulnerability scanning with manual penetration testing to flag the low-hanging fruit, as well as weed out the harder-to-find bugs from your environment. And as is always the case, compromises are going to happen, so having a fluid incident response plan in place is paramount.