Reaction of nitrobenzene with potassium ferricyanide
I'd go more for an oxidation, but on the ring (hydroxylation). 
My guess comes from this paper here : "The Hydroxylation of Aromatic Nitro Compounds by Alkalies" by O. C. Dermer.

This is very harsh (and somehow old) chemistry. 

First, for m-dinitrobenzene and sym-trinitrobenzene, hydroxylation is reported in your conditions, that is to say alcaline conditions with the help of potassium ferricyanide as oxidizing agent (reactions A and B, see reference in the paper). 

Second, the authors report the reaction C (with less than 4% yield though, according to my calculations), with a small amount of p-hydroxyazobenzene as a side-product. They did this reaction by mixing only nitrobenzene with potassium hydroxide, so I would expect the same product (o-nitrophenol) with maybe a better yield in your conditions.