cvss.dtx

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cvss --- A Package to compute and display CVSS base scores
E-mail: pierre@vivegnis.be
Released under the LaTeX Project Public License v1.3c or later
See http://www.latex-project.org/lppl.txt
----------------------------------------------------------------

The LaTeX package allows a user to compute the CVSS base score for
an input CVSS vector, as well as other artifacts (CVSS level etc)
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----------------------------------------------------------------
cvss --- A package to compute and display CVSS base scores
E-mail: pierre@vivegnis.be
Released under the LaTeX Project Public License v1.3c or later
See http://www.latex-project.org/lppl.txt
----------------------------------------------------------------

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\postamble

Copyright (C) 2022 by Pierre VIVEGNIS <pierre@vivegnis.be>

This work may be distributed and/or modified under the
conditions of the LaTeX Project Public License (LPPL), either
version 1.3c of this license or (at your option) any later
version.  The latest version of this license is in the file:

http://www.latex-project.org/lppl.txt

This work is "maintained" (as per LPPL maintenance status) by
Pierre VIVEGNIS.

This work consists of the file  cvss.dtx
and the derived files           cvss.ins,
                                cvss.pdf and
                                cvss.sty.

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\ProvidesPackage{cvss}[2022/12/02 v1.1.0 ]
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% \begin{documentation}
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%\title{
%  The \textsf{cvss} package\thanks{
%    This file describes version \fileversion, last revised \filedate.
%  }
%}
%\author{
%  Pierre VIVEGNIS\thanks{E-mail: pierre@vivegnis.be}
%}
%\date{Released \filedate}
%
%\maketitle
% \tableofcontents
%
% \newpage
% \section{Introduction}
%
% The \textsf{cvss} package allows the user to compute CVSS 3.1 base scores and use them in documents. The Common Vulnerability Scoring System (CVSS) is an open framework for communicating the characteristics and severity of software vulnerabilities. CVSS consists of three metric groups: Base, Temporal, and Environmental.
%
% This packages only deal with Base score. Temporal and Environental scores will be part of a future release.
%
% More information can be found at \texttt{https://www.first.org/cvss/specification-document}.
%
% \section{Acknowledgements}
%
% I want to thank Alexander Lill who first created a cvss project in \LaTeX (available at \texttt{https://github.com/AlexanderLill/cvss3tex}).
%
% \section{Usage}
%
% The goal of this package is to compute the CVSS base score for an input CVSS vector, and to give the user macro to output it in 3 different forms
% \begin{itemize}
%     \item The CVSS \textbf{score} (fron 0.0 to 10)
%     \item the \textbf{level} (None, Info, Low, Medium, High or Critical)
%     \item the \textbf{colored level}
%     \item the \textbf{tag} which is a colored frame around the level
% \end{itemize}
%
% All macros are expandable, which makes them usable in any context.
%
% The macros of this packages are divided in 2 categories: 
% \begin{itemize}
%      \item \textbf{direct macros} : that will take as input the CVSS base score and give you the result
%   \item \textbf{indirect macros} : that are intermediary, in the way that they only compute a form based on the precedent one.
% \end{itemize}
%
% \subsection{Direct Macros}
% \begin{function}{\cvssScore}
% \changes{v1.0.0}{2022/10/22}{Full CVSS vector as input is now supported}
% \changes{v1.1.0}{2022/12/02}{Full CVSS vector as input is now supported}
%   \begin{syntax}
%     \cs{cvssScore} \Arg{CVSS string}
%   \end{syntax}
% This is the main macro of this package, responsible for computing the base CVSS 3.1 score of an \marg{input vector} (without \texttt{CVSS3.1/}). The output of this macro is a floating point CVSS score, for example \texttt{5.4}.
% \end{function}
%
%
%
% \begin{verbatim}
% \cvssScore{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}
% \end{verbatim}
%
% This will output the following CVSS base score: \texttt{\cvssScore{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}}
%
%
% \begin{function}{\cvssScorepretty}
 %   \begin{syntax}
%     \cs{cvssScorepretty} \Arg{CVSS string}
%   \end{syntax}
% This macro will print a \textbf{colored} base CVSS 3.1 score of an \marg{input vector} (without \texttt{CVSS3.1/}). The output of this macro is a floating point CVSS score.
 % \end{function}
%
% \begin{verbatim}
% \cvssScorepretty{CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:L/A:N}
% \end{verbatim}
%
% This will output the following CVSS score: \cvssScorepretty{CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:L/A:N}
%
%
% \begin{function}{\cvssLevel}
 %   \begin{syntax}
 %     \cs{cvssLevel} \Arg{CVSS string}
 %   \end{syntax}
% This macro will output the CVSS level from an \marg{input vector} (without \texttt{CVSS3.1/}), for example \texttt{Info}.
% \end{function}
%
% \begin{verbatim}
% \cvssLevel{CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:L/A:N}
% \end{verbatim}
%
% This will output the following CVSS level: \cvssLevel{CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:L/A:N}
%
%
% \begin{function}{\cvssLevelpretty}
 %   \begin{syntax}
 %     \cs{cvssLevelpretty} \Arg{CVSS string}
 %   \end{syntax}
% This macro will output the \textbf{colored} CVSS level from an \marg{input vector} (without \texttt{CVSS3.1/}).
% \end{function}
%
% \begin{verbatim}
% \cvssLevelpretty{CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:N}
% \end{verbatim}
%
% This will output the following CVSS level: \cvssLevelpretty{CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:N}
%
%
% \begin{function}{\cvssTag}
 %   \begin{syntax}
 %     \cs{cvssTag} \Arg{CVSS string}
 %   \end{syntax}
% This macro will output a colored tag with the CVSS level inside, from an \marg{input vector} (without \texttt{CVSS3.1/}).
% \end{function}
%
% \begin{verbatim}
% \cvssTag{CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:N}
% \end{verbatim}
%
% This will output the following CVSS level: \cvssTag{CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:N}.
%
%
% \begin{function}{\cvssPrint}
%   \begin{syntax}
%     \cs{cvssPrint} \Arg{CVSS string}
%   \end{syntax}
% This macro will print all details of a CVSS string: colored level, score, and hyperlink to FIRST calculator, from an \marg{input vector} (without \texttt{CVSS3.1/}).
% \end{function}
%
% \begin{verbatim}
% \cvssPrint{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H}
% \end{verbatim}
%
% This will output the following CVSS level:
%
% \cvssPrint{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H}
%
%
%
% \subsection{Indirect Macros}
%
% \changes{v1.0.0}{2022/11/03}{First public release}
%
% \begin{function}{\category}
 %   \begin{syntax}
 %     \cs{category} \Arg{CVSS score}
 %   \end{syntax}
% This macro will output the CVSS category (None, Info, Low, Medium, High or Critical) based on the input CVSS vector passed as argument \marg{numerical score}. The mandatory argument is a floating point CVSS score, for example \texttt{5.4}.
% \end{function}
%
% \begin{verbatim}
% \category{9.9}
% \end{verbatim}
%
% This will output the following scope: \category{9.9}.
%
%
% \begin{function}{\cvssFrame}
%   \begin{syntax}
%     \cs{cvssFrame} \Arg{CVSS score}
%   \end{syntax}
% This macro will output a CVSS tag based on a CVSS \textbf{level} passed as argument. The mandatory argument must be one of the defined CVSS levels (None, Info, Low, Medium, High or Critical), for example \texttt{Info}.
% \end{function}
%
% \begin{verbatim}
% \cvssFrame{High}
% \end{verbatim}
%
% This will output the following tag: \cvssFrame{High}.
%
%

% \section{Examples}
%
% \subsection{Direct Form}

%\begin{minipage}{.85\textwidth}
% \begin{verbatim}
%\\cvssScore{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}
% \end{verbatim}
%\end{minipage}%
%\begin{minipage}{0.15\textwidth}
%\cvssScore{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}
%\end{minipage}

%\begin{minipage}{.85\textwidth}
% \begin{verbatim}
%\\cvssLevel{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}
% \end{verbatim}
%\end{minipage}%
%\begin{minipage}{0.15\textwidth}
%\cvssLevel{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}
%\end{minipage}


%\begin{minipage}{.85\textwidth}
% \begin{verbatim}
%\\cvssLevelpretty{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H}
% \end{verbatim}
%\end{minipage}%
%\begin{minipage}{0.15\textwidth}
%\cvssLevelpretty{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H}
%\end{minipage}

%\begin{minipage}{.85\textwidth}
% \begin{verbatim}
%\\cvssTag{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H}
% \end{verbatim}
%\end{minipage}%
%\begin{minipage}{0.15\textwidth}
%\cvssTag{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H}
%\end{minipage}%
%\newline
%
% We can thus embed this in text lines like this:
% \begin{verbatim}
%\\textbf{\cvssLevel{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}}-level
% \end{verbatim}
% 
% Which will be rendered like this : \textit{the vuln has a  \textbf{\cvssLevel{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}}-level and we can output it inline.}
%\subsection{Imbricated Form}

%\begin{minipage}{.5\textwidth}
% \begin{verbatim}
%\\cvssFrame{Low}
% \end{verbatim}
%\end{minipage}%
%\begin{minipage}{0.5\textwidth}
%\cvssFrame{Low}
%\end{minipage}

%\begin{minipage}{.5\textwidth}
%     \begin{verbatim}
%%\category{9.9}
%     \end{verbatim}
%\end{minipage}%
%\begin{minipage}{0.5\textwidth}
%\category{9.9}
%\end{minipage}
%\newline
%
% We can even combine them:
% \begin{verbatim}
%\\category{\cvssScore{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}}
% \end{verbatim}
%
%And this outputs: \category{\cvssScore{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}}
%
% \begin{verbatim}
%\\cvssFrame{\category{\cvssScore{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}}}
% \end{verbatim}
% And the result is: %\cvssFrame{\category{\cvssScore{CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N}}}
%
%\subsection{Test Computations}
% \begin{verbatim}
% Should be 7.3: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L}
%
% Should be 8.3: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L}
%
% Should be 9.9: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:H}
%
% Should be 9.9: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L}
%
% Should be 7.2: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N}
%
% Should be 7.1: \cvssScore{CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L}
%
% Should be 5.8: \cvssScore{CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L}
%
% Should be 5.5: \cvssScore{CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L}
%
% Should be 5.1: \cvssScore{CVSS:3.1/AV:A/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:L}
%
% Should be 4.3: \cvssScore{CVSS:3.1/AV:A/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L}
%
% Should be 2.4: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:N/A:N}
%
% Should be 0.0: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:N}
% \end{verbatim}
%
% And the results of the computations:
%
%Should be 7.3: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L}
%
%Should be 8.3: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L}%
%
%Should be 9.9: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:H}%
%
%Should be 9.9: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L}%
%
%Should be 7.2: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N}%
%
%Should be 7.1: \cvssScore{CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L}%
%
%Should be 5.8: \cvssScore{CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L}%
%
%Should be 5.5: \cvssScore{CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L}%
%
%Should be 5.1: \cvssScore{CVSS:3.1/AV:A/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:L}%
%
%Should be 4.3: \cvssScore{CVSS:3.1/AV:A/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L}%
%
%Should be 2.4: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:N/A:N}
%
%Should be 0.0: \cvssScore{CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:N}
%
% \end{documentation}
%\newpage
% \begin{implementation}
% \section{Implementation}
% \subsection{Initial set up}
%
% Load the essential support (\pkg{expl3}, \pkg{tcolorbox}, \pkg{xstring} and \pkg{hyperref}).
%    \begin{macrocode}
\RequirePackage{expl3}
\RequirePackage[skins]{tcolorbox}
\tcbuselibrary{xparse}
\RequirePackage{xstring}
\RequirePackage{hyperref}
%    \end{macrocode}
%
% Then, we define the thresholds:
%    \begin{macrocode}
% These are the thresholds
\def\scoreLow{0.1}
\def\scoreMed{4.0}
\def\scoreHigh{7.0}
\def\scoreCrit{9.0}
%    \end{macrocode}
% And finally the colors for each level (taken from the FIRST CVSS calulator website\footnote{Available at \url{https://www.first.org/cvss/calculator/3.1}})
%    \begin{macrocode}
\definecolor{color@cvss@None}{RGB}{83, 170, 51}
\definecolor{color@cvss@Low}{RGB}{255, 203, 13}
\definecolor{color@cvss@Medium}{RGB}{249, 160, 9}
\definecolor{color@cvss@High}{RGB}{223, 61, 3}
\definecolor{color@cvss@Critical}{RGB}{204, 5, 0}
%    \end{macrocode}
%
% \subsection{Round up function}
%
% First we defined the \texttt{roundup} function\footnote{This function was inspired by the following posts: \url{https://tex.stackexchange.com/a/615358/28926}} according to the precision mentionned by FIRST (\url{https://www.first.org/cvss/specification-document Appendix A}).
% .
%    \begin{macrocode}
\ExplSyntaxOn
% 
\cs_new:Npn \__CVSS_roundup:n #1 {
         \fp_eval:n { ceil(#1,1) }
         \fp_compare:nT { ceil(#1,1)=ceil(#1,0) } {.0}
}
%    \end{macrocode}
%
% \subsection{Error messages}
% We define some error message to help with the troubleshooting
%
%    \begin{macrocode}
\msg_new:nnn { CVSS } { invalid-option }{ Value~'#2'~invalid~for~#1~#3.}
\msg_new:nnn { CVSS } { invalid-structure } { CVSS~metric~#1~is~not~correct~(#2)~#3.}
\msg_new:nnn { CVSS } { invalid-length } { CVSS~vector~"#1"~is~badly~formatted~#2.}
\msg_new:nnn { CVSS } { wrong-version } { Wrong~CVSS~version~(#2)~#3.}
%    \end{macrocode}%
%
%
% \subsection{CVSS metrics parsing}
%
% Then we can define the numerical values for each of the CVSS metric (Attack Vector, Attack Complexity, ...).
% This is done by checking the string value of the argument, and outputting the correpsondant value.
% For each function, a error message is thrown if the value is not one acceptable for that metric.
%
% \subsubsection{Attack Vector}
% The value for the Attack Vector can only by either \texttt{N} (None), \texttt{A} (Adjacent), \texttt{L} (Local) or \texttt{P} (Physical).
%
%\begin{macro}{\__CVSS_parseAV}
%    \begin{macrocode}
\cs_new:Npn \__CVSS_parseAV:n #1
{
     \str_case_e:nnF {#1}
     {
          { N } { 0.85 } % Network
          { A } { 0.62 } % Adjacent
          { L } { 0.55 } % Local
          { P } { 0.2 }  % Physical
     }
     { \msg_error:nnxxx { CVSS } { invalid-option } { parseAV } {#1} {\msg_line_context:} }
}
%    \end{macrocode}%
%\end{macro}
%
% \subsubsection{Attack Complexity}
% The value for the Attack Complexity metric can only by either \texttt{L} (Low) or \texttt{H} (High).
%
%\begin{macro}{\__CVSS_parseAC}
%    \begin{macrocode}
\cs_new:Npn \__CVSS_parseAC:n #1
{
     \str_case_e:nnF {#1}
     {
          { H } { 0.44 }     % High
          { L } { 0.77 }     % Low
          
     }
     { \msg_error:nnxxx { CVSS } { invalid-option } { parseAC } {#1} {\msg_line_context:} }
}
%    \end{macrocode}
%\end{macro}
%
% \subsubsection{Privileges Required}
% The value for the Privilged Required metric can only by either \texttt{N} (None), \texttt{L} (Low) or \texttt{H} (High).
% Hoever since the computation is different wheter the Scope is changed or not, we've defined 2 functions.
%
% 3 Internal macros are thus used, one per choice (Scope unchanged and Scope change), plus the function to choose which one to take into account.
%
%\begin{macro}{\__CVSS_parsePRScopeUnchanged}
%    \begin{macrocode}
\cs_new:Npn \__CVSS_parsePRScopeUnchanged:n #1
{
     \str_case_e:nnF {#1}
     {
          { N } { 0.85 } % None
          { L } { 0.62 } % Low
          { H } { 0.27 } % High
     }
     { \msg_error:nnxxx { CVSS } { invalid-option } { parsePRScopeUnchanged } {#1} {\msg_line_context:} }
}
%    \end{macrocode}%
%\end{macro}
%\begin{macro}{\__CVSS_parsePRScopeChanged}
%    \begin{macrocode}
\cs_new:Npn \__CVSS_parsePRScopeChanged:n #1
{
     \str_case_e:nnF {#1}
     {
          { N } { 0.85 } % None
          { L } { 0.68 } % Low
          { H } { 0.50 } % High
     }
     { \msg_error:nnxxx { CVSS } { invalid-option } { parsePRScopeChanged } {#1} {\msg_line_context:} }
}
%    \end{macrocode}%
%\end{macro}
%\begin{macro}{\__CVSS_parsePR}
%    \begin{macrocode}
\cs_new:Npn \__CVSS_parsePR:nn #1#2
{
     % #1 Privilege Required
     % #2 Scope
     \str_case_e:nnF {#2}
     {
          { U } { \exp_args:Ne \__CVSS_parsePRScopeUnchanged:n {#1} }
          { C } { \exp_args:Ne \__CVSS_parsePRScopeChanged:n {#1} }
     }
     { \msg_error:nnxxx { CVSS } { invalid-option } { parsePR } {#1} {\msg_line_context:} }
}
%    \end{macrocode}%
%\end{macro}
%
% \subsubsection{User Interaction}
% The value for the User Interaction metric can only by either \texttt{N} (None) or \texttt{R} (Required).
%
%\begin{macro}{\__CVSS_parseUI}
%    \begin{macrocode}
\cs_new:Npn \__CVSS_parseUI:n #1
{
     \str_case_e:nnF {#1}
     {
          { N } { 0.85 } % None
          { R } { 0.62 } % Required
     }
     { \msg_error:nnxxx { CVSS } { invalid-option } { parseUI } {#1} {\msg_line_context:} }
}

%    \end{macrocode}
%\end{macro}
%
% \subsubsection{Confidentiality, Integrity and Availability}
% The value for the Confidentiality, Integrity or Availability metrics can only by either \texttt{N} (None), \texttt{L} (Low) or \texttt{H} (High).
% Since the values are the same for the 3 metrics, we've grouped them together.
%
%\begin{macro}{\__CVSS_parseCIA}
%    \begin{macrocode}

\cs_new:Npn \__CVSS_parseCIA:n #1
{
     \str_case_e:nnF {#1}
     {
          { H } { 0.56 }
          { L } { 0.22 }
          { N } { 0.00 }
     }
     { \msg_error:nnxxx { CVSS } { invalid-option } { parseCIA } {#1} {\msg_line_context:} }
}
%    \end{macrocode}
%\end{macro}
%
% \subsection{CVSS computation}
% \subsubsection{Impact Sub Score (ISS)}
% The value for the Impact Sub-Score (ISS) is conmputed from the Confidentiality, Availability and Integrity values, as follows
%\begin{equation}
%     ISS =      1 - \Bigr[ (1 - \text{Confidentiality}) \times (1 - \text{Integrity}) \times (1 - \text{Availability}) \Bigr]
%\end{equation}
%
% This equation is then translated into \TeX code :
%
%\begin{macro}{\__CVSS_calcISS}
%    \begin{macrocode}
\cs_new:Npn \__CVSS_calcISS:nnn #1#2#3
{
     % #1 Confidentiality Impact %High H, Low L, None N
     % #2 Integrity Impact %High H, Low L, None N
     % #3 Availability Impact %High H, Low L, None N
     1 - ( (1 - (\__CVSS_parseCIA:n {#1})) * (1 - (\__CVSS_parseCIA:n {#2})) * (1 - (\__CVSS_parseCIA:n {#3})) ) 
}
%    \end{macrocode}
%\end{macro}
%
% \subsubsection{Impact}
% The calculations for the impact depends whether the scope is changed or not, and will be computed differently:
%     \begin{equation}
%     \text{Impact} \rightarrow  
%     \begin{cases} 
%          \text{Scope Unchanged}  & 6.42 \times ISS\\
%          \text{Scope Changed}  & 7.52 \times (ISS - 0.029) - 3.25 \times (ISS - 0.02)^{15}\\
%     \end{cases}
%     \end{equation}
%
% This gives the following implementation:
%
%\begin{macro}{\__CVSS_calcImpact}
%    \begin{macrocode}
\cs_new:Npn \__CVSS_calcImpact:nn #1#2
{
     % #1 = Scope
     % #2 = ISS
     % Scope Unchanged 6.42 × ISS
     % Scope Changed 7.52 × [ISS-0.029] - 3.25 × [ISS-0.02]15
     \str_case_e:nnF {#1}
     {
          { U } { \fp_eval:n { 6.42 * (#2) } } % Scope UNCHANGED
          { C } { \fp_eval:n { 7.52 * ( (#2) - 0.029 ) - 3.25 * ( (#2) - 0.02 )^15 } } % Scope CHANGED
     }
     { \msg_error:nnxxx { CVSS } { invalid-option } { calcISC } {#1} {\msg_line_context:} }
}%
%    \end{macrocode}
%\end{macro}
%
% \subsubsection{Exploitability}
% The equation to compute the exploitability is the following:
%     \begin{equation}
%          8.22 \times \text{AttackVector} \times \text{AttackComplexity} \times \text{PrivilegesRequired} \times \text{UserInteraction}
%     \end{equation}
%
% This gives the following implementation:
%
%\begin{macro}{\__CVSS_calcExploitability}
%    \begin{macrocode}
\cs_new:Npn \__CVSS_calcExploitability:nnnnn #1#2#3#4#5
{
     % #1 Attack Vector
     % #2 Attack Complexity
     % #3 Privileges Required
     % #4 User Interaction
     % #5 Scope
     % 8.22 × AttackVector × AttackComplexity × PrivilegeRequired × UserInteraction
     8.22 * (\__CVSS_parseAV:n {#1}) * (\__CVSS_parseAC:n {#2}) * (\__CVSS_parsePR:nn {#3}{#5}) * (\__CVSS_parseUI:n {#4})%
}
%    \end{macrocode}
%\end{macro}
%
% \subsubsection{CVSS Base Score}
% Now that all the pre-requisites are calculated, we can compute the CVSS base score as follows:
%     \begin{equation}
%     \text{Base Score} =
%     \begin{cases}
%          0 & \text{if Impact $\geq 0$ } \\
%          Roundup \Bigr( min \bigr[(\text{Impact} + \text{Exploitability}), 10\bigr]\Bigr) & \text{if Scope is Unchanged} \\
%          Roundup \Bigr(min \bigr[1.08 \times (\text{Impact} + \text{Exploitability}), 10\bigr]\Bigr) & \text{if Scope is changed}
%     \end{cases}
%\end{equation}
%
% This gives the following implementation:
%
%\begin{macro}{\__CVSS_cvssBaseScore}
%    \begin{macrocode}
\cs_new:Npn \__CVSS_cvssBaseScore:nnnnnnnn #1#2#3#4#5#6#7#8 {
     % #1 Attack Vector %Network N, Adjacent A, Local L, Physical P
     % #2 Attack Complexity %Low L, High H
     % #3 Privileges Required %None N, Low L, High H
     % #4 User Interaction %None N, Required R
     % #5 Scope %Unchanged U, Changed C
     % #6 Confidentiality Impact %High H, Low L, None N
     % #7 Integrity Impact %High H, Low L, None N
     % #8 Availability Impact %High H, Low L, None N
     %
     \fp_compare:nTF { \exp_args:Ne \__CVSS_calcImpact:nn {#5}{\exp_args:Ne \__CVSS_calcISS:nnn {#6}{#7}{#8}} <= 0 }
     % IF ISC <=0
     {
          % ISC <=0
          0.0
     }{
          % ISC > 0
          \str_case_e:nnF {#5}
          {
               { U } { % SCOPE UNCHANGED
                    \fp_eval:n { \__CVSS_roundup:n { min( ((\__CVSS_calcImpact:nn {#5}{\__CVSS_calcISS:nnn {#6}{#7}{#8}}) + (\__CVSS_calcExploitability:nnnnn {#1}{#2}{#3}{#4}{#5})), 10) } }%
               }
               { C } { % SCOPE CHANGED
                    \fp_eval:n { \__CVSS_roundup:n { min( (1.08 * ((\__CVSS_calcImpact:nn {#5}{\__CVSS_calcISS:nnn {#6}{#7}{#8}}) + (\__CVSS_calcExploitability:nnnnn {#1}{#2}{#3}{#4}{#5}))), 10) } }%
               }
          }
          { \msg_error:nnxxx { CVSS } { invalid-option } { parseScope } {#1} {\msg_line_context:} }
     }%
}
%    \end{macrocode}
%\end{macro}
%
% \subsubsection{CVSS Base Score}
% Now we can use a macro to check the validity of the CVSS string and \textbf{finally} call \texttt{\textbackslash{}__CVSS_cvssBaseScore} internally. 
% This is the most important macro of this whole package, and is expandable.
%
%\begin{macro}{\cvssScore}
%    \begin{macrocode}
\NewExpandableDocumentCommand \cvssScore { m }{%
    % Check that there are 44 chars
    \int_compare:nNnTF { \str_count_ignore_spaces:n {#1} } = {44}{}{
        \msg_error:nnxx{CVSS}{invalid-length}{#1}{\msg_line_context:}
    }
    % Check CVSS: value
    \str_if_eq:eeTF {\str_range:nnn {#1} {1} {5}} {CVSS:} 
    {} {
        \msg_error:nnxxx{CVSS}{invalid-structure}{AV}{\str_range:nnn {#1} {1} {5}}{\msg_line_context:}
    }
    % Check 3.1 value
    \str_if_eq:eeTF {\str_range:nnn {#1} {6} {8}} {3.1} 
    {} {
        \msg_error:nnxxx{CVSS}{wrong-version}{3.1}{\str_range:nnn {#1} {6} {8}}{\msg_line_context:}
    }
    % Check 3.1 value
    \str_if_eq:eeTF {\str_range:nnn {#1} {9} {9}} {/} 
    {} {
        \msg_error:nnxxx{CVSS}{wrong-version}{/}{\str_range:nnn {#1} {9} {9}}{\msg_line_context:}
    }
    % Check AV value
    \str_if_eq:eeTF {\str_range:nnn {#1} {10} {12}} {AV:} 
    {} {
        \msg_error:nnxxx{CVSS}{invalid-structure}{AV}{\str_range:nnn {#1} {10} {12}}{\msg_line_context:}
    }
    % Check AC value
    \str_if_eq:eeTF {\str_range:nnn {#1} {14} {17}} {/AC:} 
    {} {
        \msg_error:nnxxx{CVSS}{invalid-structure}{AC}{\str_range:nnn {#1} {14} {17}}{\msg_line_context:}
    }
    
    
    % Check PR value
    \str_if_eq:eeTF {\str_range:nnn {#1} {19} {22}} {/PR:} 
    {} {
        \msg_error:nnxxx{CVSS}{invalid-structure}{PR}{\str_range:nnn {#1} {19} {22}}{\msg_line_context:}
    }
    
    % Check UI value
    \str_if_eq:eeTF {\str_range:nnn {#1} {24} {27}} {/UI:} 
    {} {
        \msg_error:nnxxx{CVSS}{invalid-structure}{UI}{\str_range:nnn {#1} {24} {27}}{\msg_line_context:}
    }
    
    % Check S value
    \str_if_eq:eeTF {\str_range:nnn {#1} {29} {31}} {/S:} 
    {} {
        \msg_error:nnxxx{CVSS}{invalid-structure}{S}{\str_range:nnn {#1} {29} {31}}{\msg_line_context:}
    }
    
    % Check I value
    \str_if_eq:eeTF {\str_range:nnn {#1} {33} {35}} {/C:} 
    {} {
        \msg_error:nnxxx{CVSS}{invalid-structure}{C}{\str_range:nnn {#1} {33} {35}}{\msg_line_context:}
    }
    
    % Check I value
    \str_if_eq:eeTF {\str_range:nnn {#1} {37} {39}} {/I:} 
    {} {
        \msg_error:nnxxx{CVSS}{invalid-structure}{I}{\str_range:nnn {#1} {37} {39}}{\msg_line_context:}
    }
    
    % Check A value
    \str_if_eq:eeTF {\str_range:nnn {#1} {41} {43}} {/A:} 
    {} {
        \msg_error:nnxxx{CVSS}{invalid-structure}{A}{\str_range:nnn {#1} {41} {43}}{\msg_line_context:}
    }
    
    \exp_args:Ne \__CVSS_cvssBaseScore:nnnnnnnn
    { \str_use:N \str_item_ignore_spaces:nn { #1 }{ 13 } }
    { \str_use:N \str_item_ignore_spaces:nn { #1 }{ 18 } }
    { \str_use:N \str_item_ignore_spaces:nn { #1 }{ 23 } }
    { \str_use:N \str_item_ignore_spaces:nn { #1 }{ 28 } }
    { \str_use:N \str_item_ignore_spaces:nn { #1 }{ 32 } }
    { \str_use:N \str_item_ignore_spaces:nn { #1 }{ 36 } }
    { \str_use:N \str_item_ignore_spaces:nn { #1 }{ 40 } }
    { \str_use:N \str_item_ignore_spaces:nn { #1 }{ 44 } }
}%
\ExplSyntaxOff
%    \end{macrocode}
%\end{macro}
%
% \subsection{CVSS levels}
% Since we can compute the numerical score of a given CVSS string, we can now get the classification of a CVSS vector using the 
% FIRST terminology :
%\begin{table}[!ht]
%     \centering
%     \begin{tabular}{cc}
%          \hline
%          \textbf{Rating} & \textbf{CVSS Score} \\ \hline
%          None & $0.0$ \\ 
%          Low & $0.1 - 3.9$ \\
%          Medium & $4.0 - 6.9$ \\ 
%          High & $7.0 - 8.9$ \\
%          Critical & $9.0 - 10.0$ \\ \hline
%     \end{tabular}
%\end{table}
%
% Then we can build our switch case to assign a level to the numerical CVSS score
%\begin{macro}{\category}
% This macro will output a CVSS level based on the numerical CVSS score.
%    \begin{macrocode}
\ExplSyntaxOn
\NewExpandableDocumentCommand \category { m }{%
     \fp_compare:nNnTF {#1}<{\scoreLow}{None}
     {
          \fp_compare:nNnTF{#1}<{\scoreMed}{Low}
          {
               \fp_compare:nNnTF{#1}<{\scoreHigh}{Medium}
               {
                    \fp_compare:nNnTF{#1}<{\scoreCrit}{High}
                    {Critical}
               }%
          }%
     }%
}%
\ExplSyntaxOff
%    \end{macrocode}
% We can even have a colored version of the score.
%\begin{macro}{\cvssScorepretty}
% This macro will output the \textbf{colored} CVSS level based on the CVSS vector.
%    \begin{macrocode}
\newcommand{\cvssScorepretty}[1]{%
     \def\CVSScategory{\category{\cvssScore{#1}}}%
     \textcolor{color@cvss@\CVSScategory}{\cvssScore{#1}}%
}%
%    \end{macrocode}
%\end{macro}
%\end{macro}
% We have also built a macro that will output the CVSS level based on the CVSS string, that combines \texttt{\textbackslash{}cvssScore} and \texttt{\textbackslash{}category}:
%\begin{macro}{\cvssLevel}
% This macro will output a CVSS level based on the numerical CVSS score.
%    \begin{macrocode}
\newcommand{\cvssLevel}[1]{%
     \def\CVSSscore{\cvssScore{#1}}%
     \category{\CVSSscore}%
}%
%    \end{macrocode}
%\end{macro}
% And we can even have a colored version of this level.
%\begin{macro}{\cvssLevelpretty}
% This macro will output the \textbf{colored} CVSS level based on the numerical CVSS score.
%    \begin{macrocode}
\newcommand{\cvssLevelpretty}[1]{%
     \def\CVSScategory{\category{\cvssScore{#1}}}%
     \textcolor{color@cvss@\CVSScategory}{\CVSScategory}%
}%
%    \end{macrocode}
%\end{macro}
% \subsection{Fancy prints}
% \subsubsection{Framed CVSS Level}
% For nice display of the CVSS score we created also tags, that can be used to highlight the CVSS score.
%\begin{macro}{\cvssFrame}
% First, we define \texttt{cvssFrame}, a type of \texttt{tcolorbox} we are going to use:
%    \begin{macrocode}
\DeclareTotalTCBox{\cvssFrame}{m}{
     enhanced,nobeforeafter,
     tcbox raise base,
     boxrule=0.4pt,
     top=0mm,bottom=0mm,right=1mm,left=1mm,
     arc=1pt,
     boxsep=2pt,
     colframe=color@cvss@#1,
     colback=tcbcolframe,
     coltext=black,
}{#1}%

\MakeRobust\cvssFrame
%    \end{macrocode}
%\end{macro}
%
% Then we can call this box in conjunction with \texttt{cvssScore}.
%\begin{macro}{\cvssTag}
% This macro will output the \textbf{colored} CVSS level based on the numerical CVSS score.
%    \begin{macrocode}
\newcommand{\cvssTag}[1]{%
     \def\CVSSscore{\cvssScore{#1}}%
     \cvssFrame{\category{\CVSSscore}}%
}%
%    \end{macrocode}
%\end{macro}
%
% \subsubsection{Full CVSS display}
% We can even have a nice all-in display of the category, the scrore and a hyperlink to the FIRST calculator using a combination of all the functions we've defined:
%\begin{macro}{\cvssPrint}
% {v1.1}{2022/11/30}{Full CVSS vector as input is now supported}
% This macro will output the \textbf{colored} CVSS level based on the numerical CVSS score.
%    \begin{macrocode}     
\newcommand{\cvssPrint}[1]{%
     \def\CVSSscore{\cvssScore{#1}}
     \cvssFrame{\category{\CVSSscore}} \quad \CVSSscore \quad%
     \href{https://www.first.org/cvss/calculator/3.1\##1}{#1}
}%
%    \end{macrocode}
%\end{macro}

% \end{implementation}
% \Finale
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\endinput
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%