Mingqiang Anjian 明槍暗箭 [overt shafts and covert arrows]

The phrase mingqiang yiduo, anjian nanfang 明槍易躲, 暗箭難防 [It is easy to avoid overt shafts, but the covert arrows are the hardest to escape from], also in short form mingqiang anjian 明槍暗箭 [overt shafts and covert arrows], is an analogy to express that it is relatively easy to defend yourself against open attack, but it is harder to deal with covert slandering.