This counts detected worm-propagation attempts over the CIFS or SMB file-sharing protocol. CIFS worms specifically spread by exploiting SMB file-share access to copy themselves onto other machines, so a nonzero count here, especially from an internal source, usually means an infected internal host is actively trying to spread across the file-sharing network, a more urgent finding than an external-facing counter. For example, this counter incrementing when an infected workstation attempts to drop an executable onto other machines' shared folders, similar to how Conficker propagated over SMB.