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Defensive Publications Series

January 2023

Using federated social networks for efficiently distributing CVE
Armijn Hemel

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Hemel, Armijn, "Using federated social networks for efficiently distributing CVE information", Technical
Disclosure Commons, (January 30, 2023)

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                                              Hemel: Using federated social networks for efficiently distributing CVE

             Using federated social networks for
                 efficiently distributing CVE

         This document describes an open method for distributing information related to CVEs using social
         networks (in particular the open standard ActivityPub [2]), which would allow users to get updates for
         specific CVE reports or specific events, and also potentially capture feedback from users around these
         The CVE [1] reporting system is the main vehicle for openly distributing information related to
         security vulnerabilities in software or configurations of software. CVE reports are useful but it has
         proven to be difficult to easily inform users about updates to CVE reports. In response a whole industry
         has sprung up around CVE and aggregation and distribution of information related to CVEs to fill this
         gap. The platforms used for distributing the aggregated information are closed and require payment to
         access the information.

         activitypub, fediverse, cve, cwe, security, social networks, activitystream

         CVE reports are one of the main mechanisms to distribute information related to security
         vulnerabilities in software, or configurations of software. The CVE format was created in 1999 to add
         structure to vulnerability reports which before CVE had not been standardized.
         Although very helpful there are drawbacks to the current way that CVE information is distributed and
             1. the information is effectively under control of a single government (USA) that can influence if
                CVE reports are kept under embargo or not
             2. CVE information is somewhat silently updated and not (publicly) versioned: if there are updates
                then the CVE sources are silently updated and if you want to stay up to date then you have to
                regularly visit the CVE website and check if any edits have been made. There are feeds that list
                the modifications of the last 7 days, but a user still has to actively seek and process these. For
                older updates the main data files have to be downloaded and processed.

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            3. getting updates for just the CVE reports that are of relevance is currently not possible: the only
               option is to consume all of the CVE data, plus possibly any update feeds.
            4. getting notifications for CVE reports that have certain properties is not easy. For example, many
               CVE reports are for open source packages, but the central entry point into the CVE data set is the
               number of the CVE, not the name, or name + version, of the open source package. If there would
               be a new vulnerability for a package (example: BusyBox), then the only way to be notified is to
               parse every new CVE and every updated CVE.
         The model described above is a "pull model", where people have to pro-actively visit the CVE website,
         retrieve and then process CVE data. This results in a lot of wasted effort and it is unsurprising that a
         whole industry has sprung up, where companies retrieve, process and enrich the CVE data and then
         lock it in a data silo, with tightly controlled access.
         The opposite of the "pull model" is a "push model", where users subscribe to events. Whenever there is
         an event change it will be reported to the user without the user having to do anything pro-actively.
         Events could be anything related to a CVE report or a property of a CVE report. Example events are:
            1. new CVE report is created
            2. existing CVE report is updated
            3. existing CVE report is deleted/withdrawn
            4. certain package is named in CVE report
            5. new version of package is available that fixes the security bug described in the CVE report
         and so on.
         There are various implementations of the "push model". One example that would fit our data model
         well is a social networking site. Examples of social networking sites are Twitter and Facebook. On
         these sites users can follow other users, receive updates from other users and possible interact with
         these updates (such as forwarding, liking, replying, and so on).
         CVE reports, software packages, other properties in CVE reports, or a combination of them could all be
         "users" on a social network. Whenever there is an update a new message is posted on the social
         network and all of the followers of the "user" will see it and be able to interact with it.
         One promising social network technology is W3C ActivityPub. ActivityPub is used by social networks
         such as Mastodon and other social networks in the so called Fediverse [4]. ActivityPub uses a data
         format called ActivityStreams [3], which, like ActivityPub, is a W3C standard.
         In ActivityPub there are two types of communications:
            1. client to server: users (either real users or bot) that communicate with a home server to post
               message, get messages, react to messages, subscribe to other accounts, and so on
            2. server to server: servers take data and commands that clients sent or requested and synchronize
               between each other.                                                                         3
                                              Hemel: Using federated social networks for efficiently distributing CVE

         This proposal only focuses on functionality in the "client to server" part of ActivityPub. CVE reports,
         properties of CVE reports are all users that are registered on a server and that send updates as messages
         to the outside world. These messages and actions are then distributed using "server to server"

         To implement this functionality there would be three separate tasks:
              1. download and parse CVE reports
              2. create new users based on CVE reports and properties associated with CVE reports
              3. create update messages and post to the (local) server

         Download and parse CVE reports
         The CVE website provides multiple feeds for data in JSON and XML formats that can be downloaded
         and which can then be parsed, after which interesting information can be searched or extracted.
             1. download the CVE data from the CVE website in JSON or XML form
             2. parse the data with a suitable parser (for JSON or XML), for integrity checks and to make data
                available for further inspection
             3. inspect the different fields in the data of the updated and new reports and store interesting
                information, such as CVE identifier, references to websites with more information, vulnerability
                severity, kind of problem (CWE identifiers [5]), CPE identifiers, names of packages, version
                numbers, description, and so on
             4. further inspect the "description" field to extract more information, such as source code paths or
                other file paths

         Create new users
         After parsing the all the CVE reports and extracting information from the new and updated CVE
         reports the information should be inspected to see if new "users" should be created on the server. Some
         possible reasons (but not limited to these) to create a new user could be:
             1. a new CVE number
             2. a previously unknown software package (for example from the CPE information or from the
             3. a new category of bugs (for example from the CWE field)
             4. a new vendor
         and so on.
         There are various ways to create new users:

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            1. manually: the new CVE reports can be inspected manually or scripts could report new unknown
               data, after which an administrator manually creates the new users
            2.    automatically: use a script, plus a list of which properties or combination of properties should
                 result in a new user being created

         Create update messages

         The update messages that will be sent typically are:
            1. a short identifier or text, delimited by some characters, so it is easier for a user or program to
               filter the interesting messages in a larger stream or to process them
            2. a short description of human readable text, intended for human consumption
            3. (optional) a URL pointing to a resource with more information, such as a website, pictures,
               structured data, and so on
            4. (optional) tags with extra information intended for filtering, comparable to Twitter hashtags

         [1] and
         [5]                                                                          5

Using federated social networks for efficiently distributing CVE information

Authors Armijn Hemel

License CC-BY-4.0