  We consider neutrino Minimal extension of the Standard Model ($\nu$MSM),
which by introducing only three sterile neutrinos in sub electroweak region can
explain active neutrino oscillations (via seesaw type I mechanism), baryon
asymmetry of the Universe (leptogenesis via oscillations) and dark matter
phenomena (with keV-scale sterile neutrino forming dark matter). We estimate
sterile neutrino virtual contributions to various lepton flavor and lepton
number violating processes. The contributions are too small, giving no chance
for indirect searches to compete with direct measurements in exploring
$\nu$MSM.
