Prevents the establishment of cellular antiviral state by blocking the interferon-alpha/beta (IFN-alpha/beta) and IFN-gamma signaling pathways. Blocks the IFN-induced nuclear accumulation of host phosphorylated STAT1, by interacting with the STAT1-binding region of host importin alpha-1/KPNA1 protein, thereby inhibiting the latter. Without the activity of this protein, activated STAT1 would not enter the nucleus and be unable to activate IFN-induced genes. Plays a role in assembly of viral nucleocapsid and virion budding. May act as a minor matrix protein that plays a role in assembly of viral nucleocapsid and virion budding. Interacts with host importins KPNA1, KPNA5 and KPNA6 (PubMed:27974555). Interacts with host STAT1 (PubMed:22383882). In virion, localizes on the intravirional side of the membrane. In the host cell, it is found associated with virus-induced membrane proliferation foci and to the plasma membrane where budding takes place (By similarity). Belongs to the filoviridae membrane-associated protein VP24 family.