Malware
Zanubis
According to cyware, Zanubis malware pretends to be a malicious PDF application.
Zanubis is a Android malware family.
Background
Per cyware, Zanubis disguises itself as a PDF application. The operator leverages this guise as a key for decrypting the responses sent back from the C2 server.
Source: Malpedia (Fraunhofer FKIE).