In this lesson, we're going to talk
about the exploit prediction scoring system, or EPSS.
Understanding EPSS is important
for prioritizing vulnerabilities
based on the likelihood of them being exploited in the wild.
First, let's explain what EPSS is.
EPSS is a framework designed
to help security professionals predict the likelihood
of a vulnerability being exploited.
It provides a score that helps prioritize vulnerabilities
based on real-world exploit data.
This is different from other scoring tools like CVSS,
which focuses on the potential impact of a vulnerability
rather than the likelihood of its exploitation.
EPSS is based on statistical models
that analyze various data sources,
including vulnerability databases, exploit databases,
and threat intelligence feeds.
These models consider factors
like the existence of proof of concept code,
the presence of exploits in the wild,
and the characteristics of the vulnerability itself.
The goal is to identify a score
that reflects the probability
that a given vulnerability will be exploited
within a specific timeframe.
For example, imagine you have two vulnerabilities to assess.
The first vulnerability has a high CVSS score
because it allows remote code execution
that could cause significant damage if exploited.
However, EPSS analysis shows
a low probability of exploitation
because there is no known exploits
and it's difficult to exploit.
The second vulnerability has a low CVSS score
but has a high EPSS score because there are known exploits,
and the attackers are actively using them.
In this case, EPSS helps you prioritize
the second vulnerability
despite its lower CVSS score
because it's more likely to be exploited.
To use EPSS effectively,
you need to integrate it
into your vulnerability management process.
Start by gathering EPSS scores
from the vulnerabilities identified in your systems.
These scores are usually available
through the vulnerability management tools
and databases that support EPSS.
Once you have the scores, you can compare them
to other factors like CVSS scores, asset criticality,
and your organization's risk tolerance
to prioritize which vulnerabilities to address first.
For instance, if a vulnerability with a high EPSS score
affects a critical system,
it should be prioritized for immediate remediation.
On the other hand, a vulnerability with a low EPSS score
affecting a less critical system
might be scheduled for a later remediation.
This approach helps ensure that your resources are focused
on addressing the most pressing threats.
EPSS also helps improve communication with stakeholders.
By using a data-driven approach
to explain why certain vulnerabilities are prioritized,
you can provide clear and objective justification
for your decision.
This is definitely useful
when discussing remediation efforts
with management or clients
as it demonstrates a thoughtful and evidence-based approach
to vulnerability management.
The last benefit of EPSS that I would like to touch on
is the ability to adapt to changing threat landscapes.
As new exploit data becomes available,
EPSS scores are updated to reflect the latest information.
This means your vulnerability prioritization remains
relevant and accurate over time.
For example, if a new exploit is discovered
for a previously low-risk vulnerability,
the EPSS score will increase,
prompting you to reassess its priority.
So, remember, EPSS is a valuable tool
for prioritizing vulnerabilities
based on their likelihood of exploitation.
By incorporating EPSS
into your vulnerability management process,
you can make more informed decisions
and allocate your resources more effectively.
It compliments other scoring systems like CVSS
by providing an additional layer of context
focused on real-world threat activity.