Researchers have discovered a previously undocumented backdoor and document stealer, which they have linked to the Russian-speaking Turla advanced persistent threat (APT) espionage group. The malware, which researchers call Crutch, is able to bypass security measures by abusing legitimate tools including the file-sharing service Dropbox in order to hide behind normal network traffic. Researchers said that the Crutch toolset has been designed to exfiltrate sensitive documents and other files to Dropbox accounts, which Turla operators control.
Source: https://threatpost.com/turla-backdoor-dropbox-espionage-attacks/161777/