I hope you won't have to print a List of Figures in your document with such captions...
In such a case, remember to use the optional argument of \caption:
\caption[short caption]{long caption}
Here are three alternatives.
First alternative:
\documentclass[oneside,DIV=17]{scrbook}
\usepackage[font={scriptsize,sf},labelfont={scriptsize,sf,bf}]{caption}
\usepackage[subrefformat=parens,labelfont={normalfont,scriptsize,sf},labelsep=space]{subcaption}
\setcapindent{0pt}
\begin{document}
\begin{figure}
\subcaptionbox{\label{fig:a}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:b}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:c}}{\rule{0.3\textwidth}{0.25\textwidth}}\par
\subcaptionbox{\label{fig:d}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:e}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:f}}{\rule{0.3\textwidth}{0.25\textwidth}}\par
\subcaptionbox{\label{fig:g}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:h}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:i}}{\rule{0.3\textwidth}{0.25\textwidth}}\par
\subcaptionbox{\label{fig:j}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:k}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\hspace{0.3\textwidth}
\caption{Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Ut purus elit, vestibulum ut, placerat ac, adipiscing vitae, felis.
Curabitur dictum gravida mauris. Nam arcu libero, nonummy eget, consectetuer id, vulputate a, magna. Donec vehicula augue eu neque.
Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Mauris ut leo. Cras viverra metus rhoncus
sem. Nulla et lectus vestibulum urna fringilla ultrices.\\
\llap{\subref{fig:a}} Short text fit in one line\\
\llap{\subref{fig:b}} Short text fit in one line\\
\llap{\subref{fig:c}} Short text fit in one line\\
\llap{\subref{fig:d}} Short text fit in one line\\
\llap{\subref{fig:e}} Short text fit in one line\\
\llap{\subref{fig:f}} Short text fit in one line\\
\llap{\subref{fig:g}} Short text fit in one line\\
\llap{\subref{fig:h}} Short text fit in one line\\
\llap{\subref{fig:i}} Short text fit in one line\\
\llap{\subref{fig:j}} Short text fit in one line\\
\llap{\subref{fig:k}} Short text fit in one line
}
\end{figure}
\end{document}

Second alternative:
\documentclass[oneside,DIV=17]{scrbook}
\usepackage[font={scriptsize,sf},labelfont={scriptsize,sf,bf}]{caption}
\usepackage[subrefformat=parens,labelfont={normalfont,scriptsize,sf},labelsep=space]{subcaption}
\setcapindent{0pt}
\begin{document}
\begin{figure}
\subcaptionbox{\label{fig:a}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:b}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:c}}{\rule{0.3\textwidth}{0.25\textwidth}}\par
\subcaptionbox{\label{fig:d}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:e}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:f}}{\rule{0.3\textwidth}{0.25\textwidth}}\par
\subcaptionbox{\label{fig:g}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:h}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:i}}{\rule{0.3\textwidth}{0.25\textwidth}}\par
\subcaptionbox{\label{fig:j}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:k}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\hspace{0.3\textwidth}
\caption{Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Ut purus elit, vestibulum ut, placerat ac, adipiscing vitae, felis.
Curabitur dictum gravida mauris. Nam arcu libero, nonummy eget, consectetuer id, vulputate a, magna. Donec vehicula augue eu neque.
Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Mauris ut leo. Cras viverra metus rhoncus
sem. Nulla et lectus vestibulum urna fringilla ultrices.\\
\protect\makebox[.5cm]{\subref{fig:a}} Short text fit in one line\\
\protect\makebox[.5cm]{\subref{fig:b}} Short text fit in one line\\
\protect\makebox[.5cm]{\subref{fig:c}} Short text fit in one line\\
\protect\makebox[.5cm]{\subref{fig:d}} Short text fit in one line\\
\protect\makebox[.5cm]{\subref{fig:e}} Short text fit in one line\\
\protect\makebox[.5cm]{\subref{fig:f}} Short text fit in one line\\
\protect\makebox[.5cm]{\subref{fig:g}} Short text fit in one line\\
\protect\makebox[.5cm]{\subref{fig:h}} Short text fit in one line\\
\protect\makebox[.5cm]{\subref{fig:i}} Short text fit in one line\\
\protect\makebox[.5cm]{\subref{fig:j}} Short text fit in one line\\
\protect\makebox[.5cm]{\subref{fig:k}} Short text fit in one line
}
\end{figure}
\end{document}

Third alternative:
\documentclass[oneside,DIV=17]{scrbook}
\usepackage[font={scriptsize,sf},labelfont={scriptsize,sf,bf}]{caption}
\usepackage[subrefformat=parens,labelfont={normalfont,scriptsize,sf},labelsep=space]{subcaption}
\setcapindent{0pt}
\begin{document}
\begin{figure}
\subcaptionbox{\label{fig:a}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:b}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:c}}{\rule{0.3\textwidth}{0.25\textwidth}}\par
\subcaptionbox{\label{fig:d}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:e}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:f}}{\rule{0.3\textwidth}{0.25\textwidth}}\par
\subcaptionbox{\label{fig:g}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:h}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:i}}{\rule{0.3\textwidth}{0.25\textwidth}}\par
\subcaptionbox{\label{fig:j}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\subcaptionbox{\label{fig:k}}{\rule{0.3\textwidth}{0.25\textwidth}}\hfill
\hspace{0.3\textwidth}
\caption{Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Ut purus elit, vestibulum ut, placerat ac, adipiscing vitae, felis.
Curabitur dictum gravida mauris. Nam arcu libero, nonummy eget, consectetuer id, vulputate a, magna. Donec vehicula augue eu neque.
Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Mauris ut leo. Cras viverra metus rhoncus
sem. Nulla et lectus vestibulum urna fringilla ultrices.\\
\protect\makebox[.5cm][l]{\subref{fig:a}} Short text fit in one line\\
\protect\makebox[.5cm][l]{\subref{fig:b}} Short text fit in one line\\
\protect\makebox[.5cm][l]{\subref{fig:c}} Short text fit in one line\\
\protect\makebox[.5cm][l]{\subref{fig:d}} Short text fit in one line\\
\protect\makebox[.5cm][l]{\subref{fig:e}} Short text fit in one line\\
\protect\makebox[.5cm][l]{\subref{fig:f}} Short text fit in one line\\
\protect\makebox[.5cm][l]{\subref{fig:g}} Short text fit in one line\\
\protect\makebox[.5cm][l]{\subref{fig:h}} Short text fit in one line\\
\protect\makebox[.5cm][l]{\subref{fig:i}} Short text fit in one line\\
\protect\makebox[.5cm][l]{\subref{fig:j}} Short text fit in one line\\
\protect\makebox[.5cm][l]{\subref{fig:k}} Short text fit in one line
}
\end{figure}
\end{document}

floatrowpackage can do that, is comptible with lists of figures. – Bernard Mar 20 '14 at 10:13captiondocumentation regarding work with KOMA-Script. – Speravir Mar 20 '14 at 22:45mwe, please. :-) – Speravir Mar 20 '14 at 22:47