I don't see a problem with that statement of Rosneft. Perfectly normal for a spokesman to say. On the other hand if it is a fake statement it is really easy to debunk.
Oil is their core business. If they are not able to get oil out of the ground that means losses within the millions. Therefore any oil company has a backup plan to continue oil pumping even when their IT department is completely down. (Doesn't mean their backup plan always works though).
This is probably the exact words their spokesman was told, hence this explanation/press release.