I’ll split this up in two scenarios – the first being where there is no IPS being done yet and you just want to block WannaCry, and the second being where you already have IPS measures in place protecting to your clients
No IPS in place yet
- Create an IPS protection profile containing the MS.SMB.Server.SMB1.Trans2.Secondary.Handling.Code.Execution signature
- Ensure that the protection profile is set to Block
- Apply the IPS signature to all policies governing your intra-VLAN traffic
Adding the WannaCry signature to your existing client targeting IPS profile
The target type for this signature unfortunately has the target type Server, even though client OS’s are also being targeted. This means you’ll have to manually add it to your client-targeting IPS profile.
Another point to note is that it is listed as a Rate-based signature, so ensure that your signature has a threshold of zero.
Here is more information about the relevant signature from Fortinet: https://fortiguard.com/encyclopedia/ips/43796