Within the first a part of this collection, we took an in depth take a look at CVSS and the way it works, concluding that whereas CVSS could supply some advantages, it’s not designed for use as a sole technique of prioritization. On this article, we’ll cowl some various instruments and techniques for remediation prioritization, how they can be utilized, and their execs and cons.
EPSS, first printed at Black Hat USA 2019, is (like CVSS) maintained by a FIRST Particular Curiosity Group (SIG). As famous in the whitepaper that accompanied the Black Hat discuss, the creators of EPSS purpose to fill a niche within the CVSS framework: predicting the likelihood of exploitation primarily based on historic knowledge.
The unique model of EPSS used logistic regression: a statistical method to measure the likelihood of a binary consequence by contemplating the contribution a number of impartial variables make to that consequence. For example, if I needed to make use of logistic regression to measure the likelihood of a sure/no occasion occurring (say, whether or not a given particular person will buy considered one of my merchandise), I’d look to gather a big pattern of historic advertising knowledge for earlier prospects and would-be prospects. My impartial variables can be issues like age, gender, wage, disposable revenue, occupation, locale, whether or not an individual already owned a rival product, and so forth. The dependent variable can be whether or not the particular person purchased the product or not.
The logistic regression mannequin would inform me which of these variables make a major contribution to that consequence, both optimistic or unfavorable. So, for instance, I would discover that age < 30 and wage > $50,000 are positively correlated to the result, however already owns related product = true is, unsurprisingly, negatively correlated. By weighing up the contributions to those variables, we will feed new knowledge into the mannequin and get an thought of the likelihood of any given particular person wanting to purchase the product. It’s additionally necessary to measure the predictive accuracy of logistic regression fashions (as they might lead to false positives or false negatives), which might be achieved with Receiver Working Attribute (ROC) curves.
The creators of EPSS analyzed over 25,000 vulnerabilities (2016 – 2018), and extracted 16 impartial variables of curiosity together with the affected vendor, whether or not exploit code existed within the wild (both in Exploit-DB or in exploit frameworks like Metasploit and Canvas), and the variety of references within the printed CVE entry. These have been the impartial variables; the dependent variable was whether or not the vulnerability had truly been exploited within the wild (primarily based on knowledge from Proofpoint, Fortinet, AlienVault, and GreyNoise).
The authors discovered that the existence of weaponized exploits made essentially the most vital optimistic contribution to the mannequin, adopted by Microsoft being the affected vendor (possible because of the quantity and recognition of merchandise Microsoft develops and releases, and its historical past of being focused by menace actors); the existence of proof-of-concept code; and Adobe being the affected vendor.
Apparently, the authors additionally famous some unfavorable correlation, together with Google and Apple being the affected distributors. They surmised that this can be because of Google merchandise having many vulnerabilities, of which comparatively few have been exploited within the wild, and Apple being a closed platform that menace actors haven’t traditionally focused. The inherent traits of a vulnerability (i.e., the knowledge mirrored in a CVSS rating) appeared to make little distinction to the result – though, as one may anticipate, distant code execution vulnerabilities have been extra prone to be exploited in comparison with, say, native reminiscence corruption bugs.
EPSS was initially applied in a spreadsheet. It supplied an estimate of likelihood {that a} given vulnerability can be exploited throughout the subsequent 12 months. Subsequent updates to EPSS adopted a centralized structure with a extra refined machine studying mannequin, expanded the function set (together with variables equivalent to public vulnerability lists, Twitter / X mentions, incorporation into offensive safety instruments, correlation of exploitation exercise to vendor market share and set up base, and the age of the vulnerability), and estimated the likelihood of exploitation inside a 30-day window fairly than 12 months.
Determine 1: A screenshot from the EPSS Information and Statistics web page, exhibiting the highest EPSS scores from the final 48 hours on the time the picture was captured. Word that EPSS doesn’t conclude that many of those CVEs will find yourself being exploited
Whereas a easy on-line calculator is on the market for v1.0, utilizing the newest model requires both downloading a day by day CSV file from the EPSS Information and Statistics web page, or utilizing the API. EPSS scores aren’t proven on the Nationwide Vulnerability Database (NVD), which favors CVSS scores, however they’re accessible on different vulnerability databases equivalent to VulnDB.
As famous in our earlier article on this collection, CVSS scores haven’t traditionally been a dependable predictor of exploitation, so EPSS, in precept, looks as if a pure complement — it tells you in regards to the likelihood of exploitation, whereas CVSS tells you one thing in regards to the affect. For instance, say there’s a bug with a CVSS Base rating of 9.8, however an EPSS rating of 0.8% (i.e., whereas extreme whether it is exploited, the bug is lower than 1% prone to be exploited throughout the subsequent 30 days). However, one other bug may need a a lot decrease CVSS Base rating of 6.3, however an EPSS rating of 89.9% – by which case, you may need to prioritize it.
What you shouldn’t do (because the EPSS authors level out) is multiply CVSS scores by EPSS scores. Although this theoretically provides you a severity * menace worth, do not forget that a CVSS rating is an ordinal rating. EPSS, its creators say, communicates totally different info from that of CVSS, and the 2 ought to be thought-about collectively however individually.
So is EPSS the proper companion to CVSS? Probably – like CVSS, it’s free to make use of, and presents helpful perception, but it surely does include some caveats.
What does EPSS truly measure?
EPSS offers a likelihood rating which signifies the probability of a given vulnerability being exploited usually. It doesn’t, and isn’t meant to, measure the probability of your group being focused particularly, or the affect of profitable exploitation, or any incorporation of an exploit into (as an illustration) a worm or a ransomware gang’s toolkit. The result it predicts is binary (exploitation both happens or it doesn’t – though be aware that it’s truly extra nuanced than that: both exploitation happens or we don’t know if it has occurred), and so an EPSS rating tells you one factor: the likelihood of exploitation occurring throughout the subsequent 30 days. On a associated be aware, it’s price making a be aware of that point interval. EPSS scores ought to, by design, be recalculated, as they depend on temporal knowledge. A single EPSS rating is a snapshot in time, not an immutable metric.
EPSS is a ‘pre-threat’ software
EPSS is a predictive, proactive system. For any given CVE, assuming the requisite info is on the market, it’s going to generate a likelihood that the related vulnerability can be exploited within the subsequent 30 days. You possibly can then, if you happen to select to, issue on this likelihood for prioritization, supplied the vulnerability has not already been exploited. That’s, the system doesn’t present any significant perception if a vulnerability is being actively exploited, as a result of it’s a predictive measure. To return to our earlier instance of logistic regression, there’s little level operating your knowledge by means of my mannequin and attempting to promote you my product if you happen to already purchased it six weeks in the past. This appears apparent, but it surely’s nonetheless price allowing for: for vulnerabilities which have been exploited, EPSS scores can not add any worth to prioritization selections.
Lack of transparency
EPSS has the same difficulty to CVSS with regard to transparency, though for a special motive. EPSS is a machine studying mannequin, and the underlying code and knowledge is not accessible to most members of the FIRST SIG, not to mention most of the people. Whereas the maintainers of EPSS say that “bettering transparency is considered one of our targets,” additionally they be aware that they can not share knowledge as a result of “now we have a number of industrial companions who requested that we not share as a part of the information settlement. So far as the mannequin and code, there are numerous difficult points to the infrastructure in place to help EPSS.”
Assumptions and constraints
Jonathan Spring, a researcher at Carnegie Mellon College’s Software program Engineering Institute, factors out that EPSS depends on some assumptions which make it much less universally relevant than it could seem. EPSS’s web site claims that the system estimates “the probability (likelihood) {that a} software program vulnerability can be exploited within the wild.” Nevertheless, there are some generalizations right here. For instance, “software program vulnerability” refers to a printed CVE – however some software program distributors or bug bounty directors won’t use CVEs for prioritization in any respect. As Spring notes, this can be as a result of a CVE has but to be printed for a specific difficulty (i.e., a vendor is coordinating with a researcher on a repair, previous to publication), or as a result of the vulnerability is extra of a misconfiguration difficulty, which wouldn’t obtain a CVE in any case.
Likewise, “exploited” means exploitation makes an attempt that EPSS and its companions have been capable of observe and document, and “within the wild” means the extent of their protection. The authors of the linked paper additionally be aware that, as a result of a lot of that protection depends on IDS signatures, there’s a bias in direction of network-based assaults in opposition to perimeter gadgets.
Numerical outputs
As with CVSS, EPSS produces a numerical output. And, as with CVSS, customers ought to be conscious that danger shouldn’t be reducible to a single numerical rating. The identical applies to any try to mix CVSS and EPSS scores. As a substitute, customers ought to take numerical scores under consideration whereas sustaining an consciousness of context and the techniques’ caveats, which ought to affect how they interpret these scores. And, as with CVSS, EPSS scores are standalone numbers; there aren’t any suggestions or interpretation steering supplied.
Doable future disadvantages
The authors of EPSS be aware that attackers could adapt to the system. For example, a menace actor could incorporate lower-scoring vulnerabilities into their arsenal, figuring out that some organizations could also be much less prone to prioritize these vulnerabilities. Provided that EPSS makes use of machine studying, the authors additionally level out that attackers could sooner or later try and carry out adversarial manipulation of EPSS scores, by manipulating enter knowledge (equivalent to social media mentions or GitHub repositories) to trigger overscoring of sure vulnerabilities.
SSVC, created by Carnegie Mellon College’s Software program Engineering Institute (SEI) in collaboration with CISA in 2019, could be very dissimilar to CVSS and EPSS in that it doesn’t produce a numerical rating as its output in any respect. As a substitute, it’s a decision-tree mannequin (within the conventional, logical sense, fairly than in a machine studying sense). It goals to fill what its builders see as two main points with CVSS and EPSS: a) customers aren’t supplied with any suggestions or determination factors, however are anticipated to interpret numerical scores themselves; and b) CVSS and EPSS place the vulnerability, fairly than the stakeholder, on the middle of the equation.
As per the SSVC whitepaper, the framework is meant to allow selections about prioritization, by following a call tree alongside a number of branches. From a vulnerability administration perspective, for instance, you begin by answering a query about exploitation: whether or not there’s no exercise, a proof-of-concept, or proof of lively exploitation. This results in selections about publicity (small, managed, or open), whether or not the kill chain is automatable, and ‘worth density’ (the assets {that a} menace actor would get hold of after profitable exploitation). Lastly, there are two questions on security affect and mission affect. The ‘leaves’ of the tree are 4 doable determination outcomes: defer, scheduled, out-of-cycle, or rapid.
Determine 2: A pattern determination tree from the SSVC demo web site
Usefully, the newest model of SSVC additionally consists of a number of different roles, together with patch suppliers, coordinators, and triage/publish roles (for selections about triaging and publishing new vulnerabilities), and in these instances the questions and determination outcomes are totally different. For example, with coordination triage, the doable outcomes are decline, observe, and coordinate. The labels and weightings are additionally designed to be customizable relying on a company’s priorities and sector.
Having gone by means of the choice tree, you’ll be able to export a consequence to both JSON or PDF. The consequence additionally features a vector string, which can be acquainted to anybody who learn our evaluation of CVSS within the earlier article. Notably, this vector string comprises a timestamp; some SSVC outcomes are meant to be recalculated, relying on the context. The authors of the SSVC whitepaper suggest recalculating scores which depend upon the ‘state of exploitation’ determination level as soon as a day, for instance, as a result of this will change quickly – whereas different determination factors, equivalent to technical affect, ought to be static.
Because the title suggests, SSVC makes an attempt to place stakeholders on the middle of the choice by emphasizing stakeholder-specific points and decision-based outcomes, fairly than numerical scores. One helpful consequence of that is you can apply the framework to vulnerabilities with no CVE, or to misconfigurations; one other is that stakeholders from disparate sectors and industries can adapt the framework to swimsuit their very own wants. It’s additionally pretty easy to make use of (you’ll be able to attempt it out right here), when you’ve bought a deal with on the definitions.
To our information, there hasn’t been any impartial empirical analysis into the effectiveness of SSVC, solely a small pilot examine carried out by SSVC’s creators. The framework additionally prefers simplicity over nuance in some respects. CVSS, for instance, has a metric for Assault Complexity, however SSVC has no equal determination level for ease or frequency of exploitation or something related; the choice level is just whether or not or not exploitation has occurred and if a proof-of-concept exists.
And, presumably to keep away from over-complicating the choice tree, not one of the determination factors in any of the SSVC bushes have an ‘unknown’ choice by default; as a substitute, customers are suggested to make a “affordable assumption” primarily based on prior occasions. In sure instances, this will likely skew the eventual determination, significantly close to determination factors exterior a company’s management (equivalent to whether or not a vulnerability is being actively exploited); analysts could also be uncomfortable with ‘guessing’ and err on the aspect of warning.
That being stated, it’s maybe no dangerous factor that SSVC avoids numerical scores (though some customers might even see this as a draw back), and it has a number of different elements in its favor: It’s designed to be customizable; is totally open-source; and offers clear suggestions as a ultimate output. As with a lot of the instruments and frameworks we talk about right here, a strong method can be to mix it with others; inputting EPSS and CVSS particulars (and the KEV Catalog, mentioned beneath), the place relevant, right into a tailor-made SSVC determination tree is probably going to offer you an affordable indication of which vulnerabilities to prioritize.
The KEV Catalog, operated by the Cybersecurity and Infrastructure Safety Company (CISA), is a frequently up to date listing of which CVEs menace actors are recognized to have actively exploited. As of December 2024, there are 1238 vulnerabilities on that listing, with supplied particulars together with CVE-ID, vendor, product, a brief description, an motion to be taken (and a due date, which we’ll come to shortly), and a notes area, usually containing a hyperlink to a vendor advisory.
As per CISA’s Binding Operational Directive 22-01, “federal, govt department, departments and businesses” are required to remediate relevant vulnerabilities within the KEV Catalog, together with another actions, inside a sure timeframe (six months for CVE-IDs assigned earlier than 2021, two weeks for all others). CISA’s justification for creating the KEV Catalog is just like factors we made in our earlier article: Solely a small minority of vulnerabilities are ever exploited, and attackers don’t seem to depend on severity scores to develop and deploy exploits. Subsequently, CISA argues, “recognized exploited vulnerabilities ought to be the highest precedence for remediation…[r]ather than have businesses give attention to 1000’s of vulnerabilities which will by no means be utilized in a real-world assault.”
The KEV Catalog shouldn’t be up to date on a scheduled foundation, however inside 24 hours of CISA turning into conscious of a vulnerability that meets sure standards:
- A CVE-ID exists
- “There’s dependable proof that the vulnerability has been actively exploited within the wild”
- “There’s a clear remediation motion for the vulnerability”
In keeping with CISA, proof of lively exploitation – whether or not tried or profitable – comes from open-source analysis by its personal groups, in addition to “info immediately from safety distributors, researchers, and companions…info by means of US authorities and worldwide companions…and thru third-party subscription providers.” Word that scanning exercise, or the existence of a proof-of-concept, aren’t enough for a vulnerability to be added to the Catalog.
Full disclosure: Sophos is a member of the JCDC, which is the a part of CISA that publishes the KEV Catalog
Determine 3: Among the entries within the KEV Catalog
Whereas primarily geared toward US federal businesses, many personal sector organizations have adopted the listing for prioritization. It’s not exhausting to see why; the Catalog offers a easy and manageable assortment of lively threats, in CSV or JSON codecs, which might simply be ingested and, as CISA suggests, included right into a vulnerability administration program for prioritization. Crucially, CISA is obvious that organizations shouldn’t rely solely on the Catalog, however take different sources of data under consideration
Like EPSS, the KEV Catalog is based on a binary consequence: if a bug is on the listing, it’s been exploited. If it’s not, it hasn’t (or, extra precisely, we don’t know if it has or not). However there’s lots of contextual info KEV doesn’t present, which might help organizations with prioritization, significantly sooner or later because the listing continues to develop and turn out to be extra unwieldy (and it’ll; there is just one motive a vulnerability would ever be faraway from the listing, which is that if a vendor replace causes an “unexpected difficulty with better affect than the vulnerability itself”).
For example, the Catalog doesn’t element the amount of exploitation. Has a bug been exploited as soon as, or a handful of instances, or 1000’s of instances? It doesn’t present any details about affected sectors or geographies, which could possibly be helpful knowledge factors for prioritization. It doesn’t inform you what class of menace actor is exploiting the vulnerability (apart from ransomware actors), or when the vulnerability was final exploited. As with our dialogue of EPSS, there are additionally points round what is taken into account a vulnerability, and the transparency of knowledge. Concerning the previous, a KEV Catalog entry should have a CVE – which can be much less helpful for some stakeholders – and relating to the latter, its exploitation protection is restricted to what CISA’s companions can observe, and that knowledge shouldn’t be accessible for inspection or corroboration. Nevertheless, a curated listing of vulnerabilities that are believed to have been actively exploited is probably going helpful for a lot of organizations, and offers extra info on which to base selections about remediation.
You’re maybe beginning to get a way of how a few of these totally different instruments and frameworks might be mixed to offer a greater understanding of danger, and result in extra knowledgeable prioritization. CVSS provides a sign of a vulnerability’s severity primarily based on its inherent traits; the KEV Catalog tells you which ones vulnerabilities menace actors have already exploited; EPSS provides you the likelihood of menace actors exploiting a vulnerability sooner or later; and SSVC will help you attain a call about prioritization by taking a few of that info under consideration inside a custom-made, stakeholder-specific decision-tree.
To some extent, CVSS, EPSS, SSVC, and the KEV Catalog are the ‘huge hitters.’ Let’s now flip to some lesser-known instruments and frameworks, and the way they stack up. (For readability, we’re not going to take a look at schemes like CWE, CWSS, CWRAF, and so forth, as a result of they’re particular to weaknesses fairly than vulnerabilities and prioritization.)
Vendor-specific schemes
A number of industrial entities supply paid vulnerability rating providers and instruments designed to help with prioritization; a few of these could embody EPSS-like prediction knowledge generated by proprietary fashions, or EPSS scores together with closed-source knowledge. Others use CVSS, maybe combining scores with their very own scoring techniques, menace intelligence, vulnerability intelligence, and/or details about a buyer’s property and infrastructure. Whereas these choices could present a extra full image of danger and a greater information to prioritization in comparison with, say, CVSS or EPSS alone, they’re not sometimes publicly accessible and so aren’t open to analysis and evaluation.
Some product distributors have devised their very own techniques and make their scores public. Microsoft has two such techniques for vulnerabilities in its personal merchandise: a Safety Replace Severity Score System which, like CVSS, offers a information to the severity of a vulnerability (Microsoft states that its scores are primarily based on “the worst theoretical consequence have been that vulnerability to be exploited”); and the Microsoft Exploitability Index, which goals to supply an evaluation of the probability of a vulnerability being exploited. This seems to be primarily based on Microsoft’s evaluation of the vulnerability; how troublesome it might be to take advantage of; and previous exploitation tendencies, fairly than a statistical mannequin, though not sufficient info is supplied to verify this.
Crimson Hat additionally has a Severity Scores system, comprising 4 doable scores together with a calculated CVSS Base rating. Just like the Microsoft techniques, this solely pertains to vulnerabilities in proprietary merchandise, and the means by which the scores are calculated aren’t clear.
CVE Tendencies (RIP) and alternate options
CVE Tendencies, which on the time of writing shouldn’t be lively because of X’s restrictions on utilization of its API, is a crowdsourced dashboard of data scraped from X, Reddit, GitHub, and NVD. It confirmed the ten most at present mentioned vulnerabilities primarily based on that knowledge.
Determine 4: The CVE Tendencies dashboard
As proven within the screenshot above, the dashboard included CVSS and EPSS scores, CVE info, and pattern tweets and Reddit posts, in addition to ‘printed’ dates and a measurement of dialogue exercise in the previous couple of days (or 24 hours).
Whereas CVE Tendencies could possibly be helpful for getting an thought of the present ‘taste of the month’ CVEs among the many safety neighborhood – and is also useful in acquiring breaking information about new vulnerabilities – it didn’t help in prioritization above and past new, high-impact bugs. It solely confirmed ten vulnerabilities at a time, and a few of these – together with Log4j, as you’ll be able to see within the screenshot – have been comparatively outdated, although nonetheless being mentioned due to their prevalence and notoriety.
As famous above, CVE Tendencies is at present inactive, and has been since mid-2023. As of this writing, guests to the location obtain the next message, which additionally appeared because the ultimate message on its creator’s Twitter feed:
Determine 5: CVE Tendencies’ farewell message / tweet
It stays to be seen whether or not X will calm down its API utilization restrictions, or if the creator of CVE Tendencies, Simon J. Bell, can be ready to discover different choices to revive the location’s performance.
After the demise of Bell’s web site, an organization referred to as Intruder developed their very own model of this software, in beta as of this writing, which can also be referred to as ‘CVE Tendencies.’ It comes full with a 0-100 temperature-style ‘Hype rating’ primarily based on social media exercise.
SOCRadar additionally maintains the same service, referred to as ‘CVE Radar,’ which incorporates particulars of the variety of tweets, information studies, and vulnerability-related repositories in its dashboard; in a touching gesture, it acknowledges Simon Bell’s CVE Tendencies work on its fundamental web page (as Intruder does on its About web page). Each CVE Radar and Intruder’s model of CVE Tendencies usefully incorporate the texts of associated tweets, offering an at-a-glance digest of the social media dialogue a few given bug. Whether or not the builders of both software intend to include different social media platforms, given the exodus from X, is unknown.
CVEMap
Launched in mid-2024, CVEMap is a comparatively new command-line interface software by ProjectDiscovery that goals to consolidate a number of points of the CVE ecosystem – together with CVSS rating, EPSS rating, the age of the vulnerability, KEV Catalog entries, proof-of-concept knowledge, and extra. CVEMap doesn’t supply or facilitate any new info or scores, because it’s solely an aggregation software. Nevertheless, the truth that it combines varied sources of vulnerability info right into a easy interface – whereas additionally permitting filtering by product, vendor, and so forth – could make it helpful for defenders in search of a method to make knowledgeable prioritization selections primarily based on a number of info sources.
Bug Alert
Bug Alert is a service designed to fill a particular hole for responders: It goals to alert customers solely to crucial, high-impact vulnerabilities (those that at all times appear to hit on a Friday afternoon or simply earlier than a public vacation) as shortly as doable by way of electronic mail, SMS, or cellphone notifications, with out having to attend for safety bulletins or CVE publication. It’s meant to be a community-driven effort, and depends on researchers submitting notices of recent vulnerabilities as pull requests to the GitHub repository. It’s not clear if Bug Alert’s creator continues to be sustaining it; on the time of writing, the final exercise on the Github repository was in October 2023.
As with CVE Tendencies, whereas Bug Alert could fill a helpful area of interest, it’s not designed for use for prioritization usually.
vPrioritizer
vPrioritizer is an open-source framework designed to permit customers to evaluate and perceive contextualized danger on a per-asset or per-vulnerability foundation, thereby merging asset administration with prioritization. That is achieved by utilizing CVSS scores along with “neighborhood analytics” and outcomes from vulnerability scanners. Sadly, regardless of being talked about within the SSVC whitepaper in 2019 and offered at the Black Hat USA Arsenal in 2020, it isn’t clear if vPrioritizer’s developer nonetheless maintains the mission; as of this writing, the final decide to the GitHub repository was in October 2020.
Vulntology
Vulntology is a NIST-led effort to characterize vulnerabilities (the title is a portmanteau of ‘vulnerability’ and ‘ontology’) in keeping with how they are often exploited, the potential affect of exploitation, and mitigating elements. Its said targets embody the standardization of description of vulnerabilities (for instance, in vendor advisories and safety bulletins); bettering the extent of element in such descriptions; and enabling simpler sharing of vulnerability info throughout language obstacles. An instance of a ‘vulntological illustration’ is on the market right here.
Determine 6: An illustration of Vulntology’s proposed work, taken from the mission’s GitHub repository
Vulntology is due to this fact not a scoring framework, or perhaps a determination tree. As a substitute, it’s a small step in direction of a standard language, and one which can, if it turns into widely-adopted, be of great worth in relation to vulnerability administration. A standardized method to describing vulnerabilities will surely be of use when evaluating a number of vendor safety advisories, vulnerability intelligence feeds, and different sources. We point out it right here as a result of it does have some implications for vulnerability prioritization, albeit within the long-term, and it’s making an attempt to resolve an issue throughout the vulnerability administration area. The final decide to the mission’s Github seems to have occurred in spring 2023.
Felony market knowledge
Lastly, a fast phrase on prison market knowledge and the way future analysis may put it to use for prioritization. Again in 2014, researchers from the College of Trento carried out a examine on whether or not CVSS scores are a great predictor for exploitation. They concluded that CVSS scores don’t match the charges of exploitation, however they did conclude that remediation “in response to take advantage of presence in black markets yields the most important danger discount.” It will be an attention-grabbing avenue of analysis to see if the identical continues to be true at the moment; exploit markets have elevated in dimension since 2014, and there’s a giant underground economic system devoted to the advertising and promoting of exploits.
Determine 7: A consumer presents a Home windows native privilege escalation exploit on the market on a prison discussion board
Wanting not solely on the existence of exploits in prison marketplaces, but additionally at costs, ranges of curiosity, and buyer suggestions, could possibly be additional helpful knowledge factors in informing prioritization efforts.
The problem, after all, is the issue of accessing these marketplaces and scraping knowledge; many are closed to registration and solely accessible by way of referral, cost, or popularity. And whereas the underground economic system has elevated in dimension, it’s additionally arguably much less centralized than it as soon as was. Distinguished boards could function an preliminary place to promote wares, however lots of the salient particulars – together with costs – are typically solely accessible to potential consumers by way of personal messages, and the precise negotiations and gross sales usually happen in out-of-band channels like Jabber, Tox, and Telegram. Additional analysis on this difficulty is required to find out if it could possibly be a possible supply of knowledge for prioritization.
Having examined CVSS, EPSS, SSVC, and the KEV Catalog in depth – and another instruments and frameworks extra briefly – you gained’t be shocked to be taught that we didn’t discover a magic answer, or perhaps a magic mixture of options, that can resolve all prioritization issues. Nevertheless, a mixture is sort of at all times higher than utilizing a single framework. Extra knowledge factors imply a extra knowledgeable view, and whereas this may require some technical effort up entrance, the outputs of a lot of the instruments and frameworks we’ve mentioned are designed to be simply ingested in an automatic method (and instruments like CVEMap have accomplished a few of the heavy lifting already).
In addition to combining outputs, customization can also be actually necessary. That is usually ignored, however prioritization isn’t simply in regards to the vulnerabilities, and even the exploits. In fact, they’re an enormous a part of the difficulty, however the important thing level is {that a} vulnerability, from a remediation perspective, doesn’t exist in isolation; contemplating its inherent properties could also be useful in some circumstances, however the one actually vital knowledge level is how that vulnerability might affect you.
Furthermore, each group treats prioritization in a different way, relying on what it does, the way it works, what its funds and assets appear to be, and what its urge for food is for danger.
Single, one-size-fits-all scores and suggestions don’t usually make a lot logical sense from the angle of assessing frameworks, however they make even much less sense from the angle of particular person organizations attempting to prioritize remediation. Context is all the pieces. So no matter instruments or frameworks you employ, put your group – not a rating or a rating – on the middle of the equation. It’s possible you’ll even need to do that at a extra granular stage, relying on the scale and construction of your group: prioritizing and contextualizing per division, or division. In any case, customise as a lot as you’ll be able to, and do not forget that nonetheless distinguished and in style a framework could also be, its outputs are solely a information.
With some techniques, like CVSS or SSVC, there are built-in choices to customise and tailor outputs. With others, like EPSS and the KEV Catalog, customization isn’t actually the purpose, however you’ll be able to nonetheless add context to these outcomes your self, maybe by feeding that info into different instruments and frameworks and looking out on the total image as a lot as doable.
Prioritization additionally goes past the instruments we talk about right here, after all. We’ve centered on them on this collection as a result of they’re an attention-grabbing element of vulnerability administration, however the info that ought to feed into prioritization selections will ideally come from a wide range of different sources: menace intelligence, weaknesses, safety posture, controls, danger assessments, outcomes from pentests and safety audits, and so forth.
To reiterate a degree from our first article, whereas we’ve identified a few of the downsides to those instruments and frameworks, we don’t intend in in any technique to denigrate their builders or their efforts, and we’ve tried to be honest and even-handed in our assessments. Creating frameworks like these is lots of exhausting work and requires appreciable thought and planning – and so they’re there for use, so it’s best to use them when and the place it is sensible to take action. We hope that this collection will let you do that in a secure, knowledgeable, and efficient method.