Red Hat Bugzilla – Bug 1478016
samba: SMBLoris DoS attack on SMB service
Last modified: 2017-09-06 00:50:26 EDT
Samba is vulnerable to SMBLoris vulnerability affecting SMB service causing userspace OOM on Linux.
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
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.
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.