Tag Archives: NVD

Vulchain Scanner: 5 basic principles

New Year holidays in Russia lasts 10 days this year! Isn’t it an excellent opportunity to start a new project? So, I decided to make my own active network vulnerability scanner – Vulchain.

Why? Well, first of all, it’s fun. You can make the architecture from scratch, see the difficulties invisible from the user side and try something new in software development as well.

Vulchain modular scanner

Basic principles of the project. This is not a dogma, but rather a general direction.

  1. Data layers. I would like to have this independent sets of data:
    • Raw data collections
    • Software versions detected from the raw data
    • Vulnerabilities detected from the software versions
    • Exploitability assessment data for the detected vulnerabilities
  2. Modularity. Most of functionality will be performed by the independent modules which read some data from one data level, and create some data on other data level.
  3. Transparency. Data is stored constantly on the all levels. You can easily figure out how the data was  processed, track the errors and modify modules.
  4. Neutrality. All modules are independent and easily replaceable. For example:
  5. Rationality. If it is possible to use some security utility, service or product, we will integrate with them, rather than writing our own analogue. We spend resources only on what will give us the maximum profit at a minimum of costs. 😉

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CWEs in NVD CVE feed: analysis and complaints

As you probably know, one of the ways to describe the nature of some software vulnerability is to provide corresponding CWE (Common Weakness Enumeration) ids. Let’s see the CWE links in NVD CVE base.

NVD CWEs

I have already wrote earlier how to deal with NVD feed using python in “Downloading and analyzing NVD CVE feed“. You can easily get CWEs ids iterating over cve_dict['CVE_Items'].

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Downloading and analyzing NVD CVE feed

In previous post “New National Vulnerability Database visualizations and feeds” I mentioned JSON NVD feed.

NVD JSON feed parse python

Let’s see what data it contains, how to download and analyse it. First of all, we need to download all files with CVEs from NVD database and save them to some directory.

nvd feed json download

Unfortunately, there is no way to download all the content at once. Only one year archives. We need to get urls first. Url looks like this: https://static.nvd.nist.gov/feeds/json/cve/1.0/nvdcve-1.0-2017.json.zip. Then we will download them all.

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New National Vulnerability Database visualizations and feeds

Recently, the National Institute of Standards and Technology (NIST) introduced a new version of National Vulnerability Database (NVD) website.

NIST NVD new site

I will not say that I liked this redesign:

new NVD website

IMHO, old website with US flag was much prettier and useful:

old NVD website

But the very fact that the site is developing, I really like very much. Let’s see what’s new there.

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Problems of Vulnerability Prioritization and Detection

It’s the third part of our talk with Daniil Svetlov at his radio show “Safe Environment” recorded 29.03.2017. In this part we talk about Vulnerability Prioritization and Detection:

  • Common Vulnerability Scoring System (CVSS)
  • Environmental factor
  • Manual and  automated vulnerability detection
  • Unauthenticated and authenticated  scanning
  • Why vulnerability scanners are so expensive and why the can’t detect everything

Scanner does not detect all vulnerabilities

Video with manually transcribed Russian/English subtitles:

Prioritization

– Here also the question how to prioritize vulnerabilities properly. Because if you have, as you said, two Linux servers and 20 workstations running Windows, then in principle, you may not need to do prioritization. But if you have fifteen hundred servers: some of them are on perimeter, some are in your DMZ, some are in the internal network. It is still necessary, probably, to understand correctly which vulnerabilities and where should be patched in in the first place.

Yes, this is absolutely true and it’s a very good question. How to prioritize?

Common Vulnerability Scoring System

A natural way. If we look at vulnerabilities with a CVE identifier, for them in the US National Vulnerability Database we can find CVSS Base Score. It is an assessment of vulnerability criticality level.

How is it calculated?

Some person fills the questionnaire: can it be remotely exploited – no, is there public exploit – no, etc.

CVSS framework

The result is a CVSS vector – this is a line in which you can see the main characteristics of this vulnerability and CVSS Base score is the score from 0 to 10 depending on criticality.

This is a natural way of prioritization. But sometimes this method does not give very good results.

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