What is a Zero-day Vulnerability?

If you’re in the IT space, you’ll hardly recollect December 2021 as the season for cheer, with the Apache Log4j vulnerability discovery causing shockwaves in the IT community. The finding is perhaps the most well-documented zero-day vulnerability in recent years, with a massive impact vector because of Apache’s global install base. 

Although zero-day vulnerabilities have been around for years, the Log4j incident opened up significant visibility to zero-day vulnerabilities in commonly deployed IT applications and highlighted the impact of how devastating the negative impacts can be at a large scale.

Let’s understand what a zero-day vulnerability is and the aspects that make it significant, in the context of the ITOps ecosystem you manage daily.

In simple terms, a zero-day vulnerability is a weakness or flaw in the software code which is detected and exploited with malicious intent before the developer gets to fix that flaw. 

This vulnerability category gets its name because the team of developers managing the software doesn’t get time to intervene before it is too late, thus giving them ‘zero’ days to fix the vulnerability. 

Let’s dig a little deeper to understand why zero-day vulnerabilities can be so devastating.

Let’s say your team has built an app called X. During the process of building and launching the app, your code may have unintentionally introduced a vulnerability in a critical section of the code, which did not get caught in testing cycles. When the app goes live, the software package is now available to the public – including bad actors. These cyber criminals then take the app apart and put the software package through several iterations to analyze and detect any vulnerabilities they can exploit. 

One of these bad actors detects the vulnerability in your app, which they find out does not have a legitimate fix available yet. They release the details of the exploit publicly or on the dark web. 

The more sophisticated and sponsored actors, who stand to gain monetarily, go a few steps further to gain access by bypassing the authentication mechanism and accessing critical apps and data, thus creating opportunities for malware and ransomware.

The Apache Log4j incident was heavily reported because of the widespread install base for Apache. But not every zero-day vulnerability is widely reported, much less publicized. This phenomenon is primarily because of the two-fold impact of zero-day vulnerabilities. 

1. Since such vulnerabilities are unknown to the development team, malware attackers exploit these loopholes in IT platforms and apps over months (even years) before security researchers can test and report them widely for developers to fix them. 

2. Customer data can often be more valuable today than just gaining access to IT systems. Therefore,  attackers stand to gain more by silently intruding on platforms and exposing this data on the dark web than announcing publicly that they have breached a particular IT installation or app platform.

A Check Point research report claims that the Log4j vulnerability discovered led to 800,000 attacks on installed sites within 72 hours of the discovery going public. To add to the chaos, more than 60 variants of the exploit were announced within 24 hours of the original discovery. 

As a result, IT teams might have had no time to fix the issue before it wreaked havoc. Furthermore, the case for deploying a fix becomes complicated in the case of on-premise devices since not all IT infrastructure might be centrally managed to take advantage of automated deployment measures when fixes become available.

Handling zero-day vulnerabilities can be overwhelming, considering most software used in an IT environment is sourced rather than built in-house. 

As a result, your IT team can have difficulty keeping up with the latest security developments as third-party vendors must make the fix available first, further extending your wait times to remediation. 

To ease your anxiety about mitigating zero-day exploits, refer to the list below as a ready reckoner. Zero-day vulnerability mitigation planning inherently depends on the nature of the zero-day exploit and the impact on your IT infrastructure. 

Use the following checklist to plan your zero-day exploit response. 

1. Identify the impact on your endpoints

Prepare a list of all your endpoints impacted by the zero-day exploit. If you use a comprehensive endpoint management solution, you might be able to quickly compile a list of all affected endpoints by filtering by the installed software component. Another relevant filter would be to prepare an endpoint list by group (versus employee usage) to segment critical endpoint resources further. 

2. Evaluate critical data assets connected to impacted endpoints

Preparing an inventory of all critical data assets by endpoint beforehand might be helpful to prepare you for activating such an emergency response plan. In addition, your essential data assets might be spread across various endpoints, so maintaining how these assets are organized might be helpful while evaluating which endpoints are more prone to zero-day exploits like RCE (Remote Code Execution).

3. Prioritize remediation of your endpoints

Prepare a prioritized list of endpoints based on steps 1 and 2. Be mindful of how quickly the exploit can wreak havoc on these endpoints and data assets. In addition, the nature of the exploit should help you understand how vulnerable your endpoints and data assets would be, based on possible exploit mechanisms and the likelihood of a breach.

4. Execute an action plan for affected endpoints

Once you’ve identified how severely your endpoints might be affected, execute an action plan to patch these impacted endpoints as swiftly as possible. It might not be possible to fix all affected endpoints in short order, so be prudent about your team’s options to eventually remove the affected software from a given set of server resources. Or alternatively, isolate the server in question by taking it offline, if necessary.

Zero-day vulnerability fixes can arrive at short notice. As a result, manually patching each impacted system versus automated patch deployment will substantially affect your security readiness. 

Instead, invest in comprehensive endpoint automation and patching to stay ahead of these ad hoc fixes and deploy them as soon as they become available.

Patching might come in a bit too late for your IT team to take action in some scenarios. As a proactive measure, help your IT infrastructure grow resilient with endpoint automation solutions by segmenting and isolating entire endpoint groups by impact and then deciding to take them offline or remove the app.