ASA-2019-00259 – TYPO3: Possible Arbitrary Code Execution in Image Processing

Image processing, e.g. for generating thumbnails, is actually delegated to ImageMagick (or GraphicsMagick) for the low-level processing. Whenever ImageMagick is invoked in order to convert data the mime-type of the source is identified for invoking according coders when reading data. In case an attacker manages to upload an image file containing PostScript code it will be executed on the server system when generating according visual previews or thumbnails. In order to exploit this vulnerability the following aspects must be fulfilled: GhostScript binary gs available on server system ImageMagick policy.xml settings are not strict (see below in next section) either having a valid backend user account having access to filelist module or having some frontend application that allows uploading and previewing files without according file mime-type validation