Samba is vulnerable to SMBLoris vulnerability affecting SMB service causing userspace OOM on Linux. Reference: http://seclists.org/fulldisclosure/2017/Aug/2 Reproducer: https://gist.github.com/marcan/6a2d14b0e3eaa5de1795a763fb58641e
Created samba tracking bugs for this issue: Affects: fedora-all [bug 1478017]
max smbd processes (G) This parameter limits the maximum number of smbd(8) processes concurrently running on a system and is intended as a stopgap to prevent degrading service to clients in the event that the server has insufficient resources to handle more than this number of connections. Remember that under normal operating conditions, each user will have an smbd(8) associated with him or her to handle connections to all shares from a given host. Default: max smbd processes = 0 Example: max smbd processes = 1000
Mitigation: 1. use 'max smb processes = <max number of processes allowed>' in /etc/samba/smb.conf to limit maximum number of smbd processes. 2. Limit the exposure of TCP port 445 to internet.
External Reference: https://access.redhat.com/security/vulnerabilities/smbloris
Statement: There is currently no upstream patch for this issue. The Red Hat Product Security Team advises customer to use the "Mitigation" provided, to resolve this security flaw. We shall revisit this issue, when an appropriate upstream patch is available.